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Pitfalls in the immunophenotyping of leukaemia and leukaemic lymphomas: survey of 9 years of quality control in The Netherlands. Dutch Cooperative Study Group on Immunophenotyping of Haematological Malignancies (SIHON).

During the last decade, biannual quality controls were performed in the Netherlands focusing on the immunophenotyping of leukaemic haematological malignancies. All results on 48 specimens obtained by 18-34 laboratories were analysed. The interlaboratory variability and percentages of discordant results from 30 markers were measured by assessing false positive or negative (cut-off 10%) results in comparison with median results of the group. The quality of the immunophenotypic diagnoses obtained from the interpretation of these markers in relation to clinical data was evaluated by scoring them as 'correct', 'minor fault', 'major fault', 'not based upon the markers used', and 'no diagnosis', CD3, CD8, CD19, CD61 and Sm lambda had the lowest percentage discordancy (sum of total negative and positive discordant values 5-7.5% of assays): CD13, CD15, cyCD22, CD33 and TdT scored worst with 14-20% cumulative discordancy. The analysis of each diagnosis yielded 78% acceptable immunophenotypic conclusions (correct 54% and minor fault 24%). It appeared that the major faults in immunophenotyping were caused by suboptimal antibody selection and erroneous interpretation of the results obtained, rather than by technical errors. Large differences per diagnostic category were observed, with the best scores for mature B-cell leukaemias, AMLs and common-ALL, and the poorest scores for T-cell malignancies which were correctly diagnosed in only 24-60% of specimens. Mature T-NHL and T-PLL were mistakenly diagnosed as T-ALL by 40% of the centres. Misinterpretation of TdT immunofluorescence or omitting this marker contributed significantly to these wrong diagnoses. A median of 4% of immunophenotypic diagnoses were not based on a correct panel of antibodies, but upon the morphology of the accompanying blood smear, and was often flawed by overinterpretation. In conclusion, both the technical performance of immunophenotyping of haematological malignancies in The Netherlands and the procedure by which a final diagnosis is obtained needs improvement, especially for T-cell malignancies.

False Negative Reactions↗

[Immunophenotype classification of macular corneal dystrophy: first case report of immunophenotype I A outside of Saudi Arabia. A clinical histopathological correlation with immunohistochemistry and electron microscopy].

BACKGROUND: Macular corneal dystrophy can be classified into three different immunophenotypes according to presence and distribution of sulfated keratan sulfate (SKS) in the cornea and serum levels of SKS. Immunophenotype I A has yet only been reported in patients with macular corneal dystrophy from Saudi Arabia. MATERIAL AND METHODS: Case report of a patient with macular corneal dystrophy type I A from Germany. Indirect immunohistochemistry for sulfated keratan sulfate was performed on the corneal buttons obtained after perforating keratoplasty (monoclonal antibodies 3D12/H7 and 5-D-4). The serum concentration of SKS was determined using the monoclonal antibody 5-D-4 in a serum antigen-inhibition assay. Immunogold labeling with the 5-D-4 antibody was performed to allow ultrastructural localization of SKS in the cornea. RESULTS: The patient demonstrated the typical clinical picture of macular corneal dystrophy. Serum levels of SKS were not detectable. Positive immunohistochemistry for SKS was found only within single keratocytes of both corneae without staining of the stroma (3D12/H7 and 5-D-4). Immunogold labeling localized SKS within stromal keratocytes and proved this patient to suffer from macular corneal dystrophy immunophenotype I A. CONCLUSION: Macular corneal dystrophy immunophenotype I A can be found outside Saudi Arabia in a German patient. All three immunophenotypes of macular corneal dystrophy are present in corneal buttons from German patients.

Adult↗

The immunophenotype of adult acute myeloid leukemia: high frequency of lymphoid antigen expression and comparison of immunophenotype, French-American-British classification, and karyotypic abnormalities.

Immunophenotyping has become common in the diagnosis and classification of acute leukemias and is particularly important in the proper identification of cases of minimally differentiated acute myeloid leukemia (AML-M0). To evaluate the immunophenotype of adult AML, 106 cases were studied by cytochemical analysis and by flow cytometry with a panel of 22 antibodies. The results were compared with the French-American-British (FAB) Cooperative Group classification, as well as with available cytogenetic data on each case. CD45, CD33, and CD13 were the most commonly expressed antigens (97.2%, 95.3%, and 94.3%, respectively). Lymphoid-associated antigens were expressed in 48.1% of cases. CD20 was the most commonly expressed lymphoid antigen (17%), although often expressed in only a subpopulation of leukemic cells, followed by CD7 (16%), CD19 (9.8%), CD2 (7.5%), CD3 (6.7%), CD5 (4.8%), and CD10 (2.9%). Some immunophenotypes correlated with FAB type, including increased frequency of CD2 expression in AML-M3; lack of CD4, CD11c, CD36, CD117, and HLA-DR expression in AML-M3; increased frequency of CD20 and CD36 expression and lack of CD34 expression in AML-M5; increased frequency of CD5 expression in AML-M5a; and increased frequency of CD14 expression in AML-M5b, when compared with all other AMLs (P < .05). When compared with AML-M5b, AML-M5a demonstrated a lack of CD4 expression and a high frequency of CD117 expression. Complete morphologic and cytogenetic agreement between AML-M3 and t(15;17) was present, and four of five cases of AML-M4Eo demonstrated inv(16). The remaining case of M4Eo was characterized by a 6;9 translocation, and two other inv(16) cases were not classified as M4Eo. Expression of CD2 was present in two t(15;17) cases and in one inv(16) case, but expression of this antigen was not restricted to AML cases with these karyotypic abnormalities. Similarly, expression of CD19 was not specific for t(8;21) AML. All t(8;21) leukemias demonstrated M2 morphology. With the exception of M3, M4Eo, and a subgroup of M2 leukemias, the FAB classification does not appear to define cytogenetically distinct disease groups in adult AML. Immunophenotypically distinct profiles were identified in the M3 and M5 morphologic groups of the FAB classification. Immunophenotyping studies are helpful in the determination of myeloid lineage. In general, however, they are not sufficiently specific alone to be useful in precisely identifying either FAB or cytogenetically defined disease subtypes.

Acute Disease↗

The immunophenotype of blast transformation of chronic myelogenous leukemia: a high frequency of mixed lineage phenotype in "lymphoid" blasts and A comparison of morphologic, immunophenotypic, and molecular findings.

Immunophenotypic studies have a limited role in the diagnosis of chronic myelogenous leukemia (CML) but are increasingly being used in CML blast transformation (BT). Determination of the cell lineage of CML blasts is clinically important because patients with lymphoid blast transformation have a better response to chemotherapy and longer survival than those with other lineages. We studied the morphologic, cytochemical, immunophenotypic, cytogenetic, and molecular features of 20 patients with Philadelphia chromosome-positive CML and more than 10% blast cells in peripheral blood or bone marrow. The blasts were morphologically heterogeneous. CD33 was expressed in 19 cases (95%), followed by CD13 (85%), CD11c (80%), CD36 (60%), CD117 (40%), and CD15 (30%). Seven cases (35%) had a precursor-B lymphoid immunophenotype, and 13 (65%) had a predominantly myeloid immunophenotype. Of the former group, of which only one had a pure lymphoid phenotype, terminal deoxynucleotidyl transferase (TdT) and CD19 were expressed in 100%, CD10 in 85.7%, and CD20 in 14.3%. Of the latter group, all 13 expressed from 3 to 6 myeloid antigens, with 46.2% myeloperoxidase positive and 69.2% CD61 positive. No cases were interpreted as T lineage, but the T-cell antigens CD3, CD4, CD5, and CD7 were expressed in 5.0, 40.0, 5.3. and 30.0% of all cases, respectively. In most cases, the immunophenotype of the CML blasts could not be predicted from their morphologic features. Polymerase chain reaction showed that 80.0% of the lymphoid group and 37.5% of the myeloid group had immunoglobulin heavy-chain gene rearrangements. The frequent lineage infidelity of the blast cells in CML BT seems to be related to the stem cell origin of this disorder. Such lineage infidelity, however, makes classification of many cases difficult and the significance of and criteria for biphenotypic blast crisis of CML is yet to be determined.

Adult↗

Immunophenotyping of non-Hodgkin's lymphoma. Lack of correlation between immunophenotype and cell morphology.

The establishment of Clusters of Differentiation for T- and B-lymphoid cells during International Workshops on Human Leukocyte Differentiation Antigens prompted the authors to evaluate the immunophenotypes in 160 cases of non-Hodgkin's lymphoma (NHL). In this group, 130 were of B-lymphocyte lineage (117 by monotypic immunoglobulin expression), and 30 of T-cell lineage. In the B-NHL series the expression of immunoglobulin isotypes, B-cell maturation/differentiation antigens of CD9, CD10, CD19-24, CD37, and CD38 (OKT10), HLA-DR and peanut agglutinin binding showed no significant relationship with histopathologic diagnosis as defined by the Kiel classification. Of the T-cell markers, CD5, CD6, and CD7 showed lineage promiscuity by their presence on some B-NHL. Conversely, the authors grouped the cases according to phenotypes (either CD antigens or immunoglobulin isotypes) which occur in distinct stages of (physiologic) B-cell maturation/differentiation. Eighty-six of the 130 cases could be fitted according to CD phenotype expression. This approach did not yield a significant relationship between phenotype and individual histopathologic categories either. The staging by CD phenotype and by immunoglobulin isotype yielded different results in this respect. Most B-NHL had an intermediate stage of B-cell maturation/differentiation. In the T-NHL series most cases showed a phenotype (CD1-CD8, CD38, TdT, and peanut agglutinin binding capacity) compatible with mature T-lymphocyte characteristics. The exceptions were lymphoblastic convoluted lymphomas, which exhibited an immature immunophenotype. It is concluded that NHL in distinct histopathologic categories are heterogeneous in immunologic phenotypes, and that the immunophenotype of lymphoma cells has no evident association with that of their presumed counterparts in physiologic cell maturation/differentiation.

Antigens, Differentiation, B-Lymphocyte↗

Immunophenotyping of low-grade B-cell lymphoma in blood and bone marrow: poor correlation between immunophenotype and cytological/histological classification.

Results of immunophenotypic examinations of peripheral blood and/or bone marrow (BM), involved in low-grade B-cell non-Hodgkin's lymphomas, were compared with the results of cytomorphological and histopathological examinations in 133 adult patients. 69 cases of chronic B-lymphocytic leukaemia (B-CLL), 16 centrocytic (CC) lymphomas, 14 centroblastic-centrocytic (CB/CC) lymphomas, 15 immunocytomas (IC), 10 cases of hairy cell leukaemia (HCL), four prolymphocytic leukaemias (PLL), two B-CLL in transformation, one splenic lymphoma with villous lymphocytes (SLVL), one hairy cell leukaemia variant (HCL-V), and one lymphocytic lymphoma (LC) were classified according to the Kiel and/or FAB classification. Leukaemic disease was found in 105 cases. The following markers were used for immunocytology (APAAP technique) of blood and/or BM smears: CD19, CD5, CD10, CD11c, CD14, CD21, CD22, CD23, CD25, CD38 and TdT. All cases tested showed CD19, but no TdT expression. Every case of HCL had a distinct phenotype with expression of CD11c, CD22 and CD25 and the lack of CD5 and CD23 antigens. In all other NHL cases a very heterogenous expression of CD-antigens with no significant correlations to the cytomorphological subtypes was found. The expression of CD5 is a frequent but inconstant finding in lymphoproliferative diseases other than B-CLL, so 50% of CB/CC, 75% of CC and 80% of IC were CD5 positive. Our results indicate that, with the exception of HCL, the diagnostic relevance of immunophenotyping for the classification of cytomorphologically and histopathologically defined subtypes in blood and/or BM is of very limited value.

Aged↗

CD45RA+ immunophenotype in mycosis fungoides: clinical, histological and immunophenotypical features in 22 patients.

BACKGROUND: Mycosis fungoides (MF) is a cutaneous T-cell lymphoma (CTCL) usually characterized by a T-helper memory phenotype (CD3+, CD4+, CD8-, CD45R0+). Aberrant phenotypes are more commonly seen in the tumor stages. CD45RA expression has so far been documented in only a few cases of CD8+ or TCR gamma delta+ CTCL and in some pagetoid reticulosis cases. METHODS: Two hundred and fifteen MF patients were immunophenotyped in our laboratory between January 1992 and June 2000 and 22 cases of CD45RA+ MF (8.7%) were identified by immunohistochemical analysis. RESULTS: The majority of these CD45RA+ patients (20/22) showed a patch-plaque stage disease and an indolent clinical course, as expected in early-stage MF. The remaining 2 patients presented with stage IIB and IVA MF, and were characterized by an aggressive clinical course, with systemic spread. The immunohistochemical analysis revealed that CD45RA+ neoplastic cells belonged to the memory compartment, displaying a CD62L-, CD11a+, CD29+ phenotype. Most patients showed aberrant phenotypes, with a loss of T-cell lineage markers and expression of cytotoxic molecules or gamma-delta chain of the T-cell receptor. CONCLUSIONS: Our data show that CD45RA+ MF is a rare variant of CTCL and shares with the classic MF cases both the clinical features and disease course, even if it is characterized by a higher incidence of immunopathological abnormalities.

Adult↗

Relative contributions of enzyme cytochemistry and flow cytometric immunophenotyping to the evaluation of acute myeloid leukemias with a monocytic component and of flow cytometric immunophenotyping to the evaluation of absolute monocytoses.

We evaluated the contributions of enzyme cytochemical stains and flow cytometric immunophenotyping (FCI) data to detection of monocytic cells (MCs) in acute myelomonocytic and acute monocytic leukemias (AMMLs and AMoLs) and compared FCI findings in AMoL, chronic myelomonocytic leukemia (CMML), and normal peripheral blood (PB) and bone marrow (BM) monocytes to classify and evaluate absolute monocytoses (AMs). We reviewed 10 AMMLs and 6 AMoLs with a-naphthyl-acetate esterase (ANAE) and a-naphthyl-butyrate esterase stains and a complete FCI profile and compared FCI data for 6 AMoLs, 7 CMMLs, 2 AMs, and normal monocytes. We confirmed increased sensitivity of ANAE staining to FCI data in detecting MCs in AMML and AMoL. CD14 was insensitive for confirming MCs; other characteristic markers of MCs were absent or partially lost in AMML and AMoL. Aberrant expression of CD56 (detected in 50% of AMMLs and AMoLs), CD34, and CD117 indicated malignancy. The mature MCs of the CMMLs revealed variable FCI abnormalities (partial loss of CD13, CD14, and CD15; expression of CD56), as in the monoblasts of AMoL. These FCI abnormalities in morphologically mature MCs might indicate markers for CMML. AMs revealed FCI abnormalities, indicating clues to their correct classification as CMML.

Biomarkers, Tumor↗

[Biological properties and sensitivity to induction therapy of differentiated cells expressing atypical immunophenotype in acute leukemia of children].

The atypical immunophenotype (expression of determinant from the another cell lines than line of origin) of acute leukaemia blast cells are noted in a part of cases. The characteristics and classification of atypical immunophenotypes are not unified and the clinical significance is not yet fully described. The purpose of the study was: precise description of atypical immunophenotypes and analysis of their frequency in different types of acute leukaemia, analysis of association between expression of atypical immunophenotypes and the level of initial leukocytosis, percentage of blast cells in peripheral blood, expression of CD34, analysis of frequency of multidrug resistance molecule (MDR) expression and association between MDR and immunophenotypes of leukaemia cells, analysis of association between atypical immunophenotypes and proliferation, secretion of cytokines (IL-6, TNF) and spontaneous apoptosis of leukaemia cells, analysis of association between atypical immunophenotypes and sensitivity to induction therapy. The bone marrow samples used for routine diagnosis were the basic source of leukaemia cells for the study. The morphological examination and the immunophenotypes of leukaemia cells were done for classification of leukaemia. The immunophenotype and the expression of MDR determination was performed with flow cytometry after staining the cells with monoclonal antibodies (directly labelled) for CD determinants and MDR. The spontaneous proliferation of leukaemia cells was studied with 3H-Thymidine uptake after 3-days culture in vitro. The type of proliferation (autocrine, paracrine) was defined based on comparison of shorter (3-days) and longer (6-days) culture of leukaemia cells. The percentage of apoptotic leukaemia cells was analysed with flow cytometry after staining of leukaemia cells with propidium iodide in subdiploidal region of DNA profile. The secretion of cytokines (IL-6 and TNF) was determined by ELISA technique in supernatants of leukaemia cells cultured for 24 hr in vitro. The biological activity of TNF was determined in the bioassay using L929 mouse cells line. The effect of induction therapy was estimated base on time of cytoreduction in peripheral blood and time of reaching the haematological remission in bone marrow. The study included 230 children with acute leukaemia: lymphoblastic (ALL)--189 children (ALL-proB--19, common ALL--139, ALL-B--5 and ALL-T--26) and myeloid (AML)--34 children. Moreover, into the study 2 cases of acute undifferentiated leukaemia (AUL) and 3--acute mixed lineage leukaemia (AMLL) and 2--biphenotypic leukaemia were included. The all studies of leukaemia cells had been done before the therapy was installed. Basing on the assay of immunophenotypes the following forms of atypical immunophenotypes were distinguished: immunophenotype incomplete, hyperexpression of determinants, asynchronic immunophenotype, coexpression of determinants from the other line than origin of leukaemia cells, balanced expression of determinants from two cells lines (biphenotypic leukaemia) and three cells lines (mixed lineage leukaemia). The atypical immunophenotypes were observed in: 21.1% ALL-proB cases, 34.5% common ALL cases, 42.3% ALL-T and 58.8% AML. The most common form of atypical immunophenotypes was coexpression of determinants from the other cell line. There were no associations between atypical immunophenotypes and the level of initial leukocytosis and percentage of blast cells in peripheral blood. The expression of CD34, recognised as the one of markers of poorer prognosis, was analysed regarding the leukaemia type and immunophenotype of leukaemia cells. The lowest frequency of CD34 expression was noted in ALL-T (28.5%), the highest one in common ALL (62.3%). The significant association between frequency of CD34 and atypical immunophenotypes was observed in AML and ALL-T. Moreover, in common ALL the expression of CD34 was significantly higher when myeloid determinants were present on common ALL cells (common ALL + My) in comparison to coexpression of lymphoid determinants (common ALL + Ly). The frequency of MDR expression (cases with more than 10% of MDR positive cells) was in range between 16.6% in ALL-proB and 78.9% in AML. The mean percentage of cells expressing MDR was low in ALL-proB (10.7%) and high in ALL-T (39.6%). In ALL the atypical immunophenotype was associated with expression of MDR whereas in AML this association did not appear. The common ALL + My leukaemia cells showed higher ability to proliferation in vitro compare with common ALL without atypical immunophenotype. The opposite results were observed in AML. AML leukaemia cells with coexpression of lymphoid determinants (AML + Ly) showed lower proliferation in vitro than AML without atypical immunophenotype. The autocrine type of proliferation was observed frequently in AML (35.3% of cases) than in ALL (14.2%). This type of spontaneous proliferation was observed only when the leukaemia cells without changes in immunophenotype had been cultured. The low level in common ALL and high in AML of spontaneous release of IL-6 and TNF were noted. AML leukaemia cells without changes in immunophenotype released significantly higher amount of these cytokines than AML cells with atypical immunophenotypes (AML + Ly). The above observations suggested that coexpression of myeloid determinants in ALL and lymphoid determinants in AML were leading to changes of some biological properties of these cells. The ALL + My leukaemia cells behaved similarly to myeloid leukaemia cells, while AML + Ly cells showed features of lymphoid leukaemia cells. The common ALL and AML leukaemia cells with atypical immunophenotype showed higher percentage of apoptotic cells (16.1% and 16.9% respectively) comparing to common ALL and AML without changes in immunophenotype (9.0% and 9.2% respectively). The weak negative association of MDR expression and apoptosis suggested the indirect inhibiting influence of MDR on ability of cells to undergo into the apoptosis process. In common ALL and AML with typical immunophenotype of leukaemia cells and ALL-T the level of apoptosis was associated positively with the spontaneous proliferation, whereas this relation was negative in AML with atypical immunophenotype. There were no differences of the time of cytoreduction of leukaemia cells in peripheral blood in B cell origin ALL and AML with or without changes in immunophenotype of blastic cells. In ALL-T + My the time of cytoreduction was significantly longer. However, the expression of CD10 in ALL-T had no effect on cytoreduction time. The expression of MDR in ALL-T with typical immunophenotype was independent marker associated with elongation of cytoreduction time. The time of reaching the complete haematological remission was analysed in 186 children with ALL (ALL-proB--18 children, common ALL--137 children, ALL-T--26) and only 19 children with AML. The longest period of time for reaching the remission was observed in AML, shortest--in ALL-T. In common ALL and ALL-T the expression of myeloid determinants was associated with significant elongation of time of reaching the remission. In the majority of AML cases with coexpression lymphoid determinants, the complete remission was reached. The time needed for the reaching of remission was similar in AML with or without coexpression of lymphoid determinants. The results of this study suggest that coexpression of determinants from the other cell line modify the biological properties of leukaemia cells into the cells from the line of origin of these additional determinants. In ALL the combined expression of MDR and atypical immunophenotype of leukaemia cells were associated with poorer response to induction therapy. In AML the combined expression of CD34 and atypical immunophenotype were associated with response to induction therapy by reaching the complete remission, but without any influence on the time of reaching this remission. The results of analysis of cytoreduction time and time of reaching the remission improved the usefulness of these parameters for the estimation of response to the induction therapy. The clinical importance of these observations consist in characterisation of leukaemia cells potentially resistant to the induction therapy what may suggest the modification and individualization of the induction therapy.

Adolescent↗

Immunohistochemical classification of primary and recurrent macular corneal dystrophy in Germany: subclassification of immunophenotype I A using a novel keratan sulfate antibody.

Macular corneal dystrophy (MCD) is an autosomal recessive disease characterized by abnormal deposition of glycosaminoglycans in corneal stroma, keratocytes, Descemet's membrane and corneal endothelium. According to the presence and distribution of sulfated keratan sulfate (KS)-epitopes in serum and cornea (using mAb 5-D-4), MCD can be classified into three immunophenotypes: type I, I A and II. The purpose of this study is to evaluate the immunophenotype of primary and recurrent MCD and to analyze the reactions of a novel KS-antibody in MCD corneas, which recognizes an epitope localized in the binding region of KS-chains to the core protein (mAb 3D12/H7). Indirect immunohistochemistry for KS (mAbs 3D12/H7 and 5-D-4) was performed on 44 corneas of 37 patients with MCD including two recurrences. Immunogold labeling was used to localize KS ultrastructurally within keratocytes. The serum concentration of KS (cKS) was determined in a serum antigen-inhibition assay. Immunohistochemically, no reaction was observed using mAb 5-D-4 in 18 corneas of 16 patients (43% of 37 patients; immunophenotype I). Positive reactions within single keratocytes but not in the stroma, were seen in 22 corneas of 17 patients (46% of 37 patients; immunophenotype I A) and positive reactions in keratocytes and extracellular stroma were found in four corneas of four patients (11% of 37 patients: immunophenotype II). For analysis of cKS a total of seven samples was available. Whereas in the samples of the five patients with immunophenotypes I and I A cKS was below the limit of detection, in the two sera from patients with immunophenotype II, cKS was normal (cKS = 1243 and 1380 nmol l(-1)). The two recurrences demonstrated immunophenotype II. Using mAb 3D12/H7, MCD immunophenotype I A can be further subclassified in type I A 1 (lacking reaction with mAb 3D12/H7 in keratocytes; 77%) and type I A 2 (positive reaction with mAb 3D12/H7 within keratocytes; 23%). MCD immunophenotype I A can not only be found in Saudi Arabia, but is as common as immunophenotype I in German patients. The only recurrences of MCD necessitating regrafting occurred in two patients with immunophenotype II possibly suggesting a higher risk for recurrence in this immunophenotype. The mAb 3D12/H7 allows a further subclassification of immunophenotype I A into type I A1 and 2. This points to a broader spectrum of MCD immunophenotypes and indirectly to a broader corneal proteoglycan pathology in MCD.

Antibodies, Monoclonal↗

B-cell differentiation immunophenotypes in classical Hodgkin lymphomas.

The bcl6/CD10/MUM1/CD138 B-cell differentiation immunophenotypes were analysed in 101 cases of classical Hodgkin lymphomas (cHL) aiming to elucidate their histogenesis. Three major bcl6/CD10/MUM1/CD138 immunophenotypes were distinguished on the basis of the immunohistochemical positivity of Hodgkin and Reed-Sternberg (H/RS) cells: (a) the late germinal center (GC)/early post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138-); 59/101 cases (59%), (b) the post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138+); 24/101 cases (24%) and (c) the indeterminate immunophenotype (bcl6+/CD10-/MUM1+/CD138-: 14 cases and bcl6+/CD10-/MUM1+/CD138+: four cases); 18/101 cases (18%). The above findings indicate that H/RS cells in most cHL display bcl6/CD10/MUM1/CD138 immunophenotypes consistent with late GC/early post-GC or post-GC B-cell differentiation. In addition, H/RS cells in a small fraction of cHL display indeterminate bcl6/CD10/MUM1/CD138 immunophenotypic profiles which are characterized by simultaneous expression of GC, late GC/early post-GC and post-GC B-cell differentiation proteins. These immunophenotypic profiles do not correspond to the differentiation immunophenotypes of normal B-cells and their identification in a part of cHL suggests that the differentiation process of H/RS cells is not complete in a fraction of these cells and/or is still ongoing at the time of observation.

Antigens, Differentiation↗

Karyotype correlates with peripheral blood morphology and immunophenotype in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is recognized as a distinct entity. However, morphologic and immunophenotypic heterogeneity exist. Twenty-six patients with CLL were studied to investigate whether an association exists among peripheral blood karyotype, morphology and immunophenotype. Clonal cytogenetic abnormalities were detected in 14 patients (53%), using conventional karyotyping techniques in addition to fluorescence in situ hybridization (FISH) for chromosome 12. By FAB guidelines, 7 of the 8 patients (88%) with trisomy 12 had mixed cell morphology compared to only 3 of 18 (17%) without trisomy 12 (P = .004). One patient (12%) with trisomy 12 had lymphocyte morphology typical for CLL. Six of the eight (75%) with trisomy 12 had atypical immunophenotype including one or more of the following: strong CD20 expression, strong surface light chain expression, or absence of CD23 expression. Only 2 of the 18 patients (11%) without trisomy 12 had atypical immunophenotype (P = .005). None of the three patients with clonal structural abnormalities of chromosome 13q14 had mixed cell morphology or atypical immunophenotype. One of the 12 patients (8%) without clonal cytogenetic abnormalities had mixed cell morphology and one had atypical immunophenotype. This study suggests that a correlation exists among karyotype, morphology, and immunophenotype in CLL, and that CLL subgroups can be identified based on laboratory parameters. Although normal karyotypes or clonal structural abnormalities of 13q14 are associated with morphology and immunophenotype considered typical for CLL, trisomy 12 is associated with mixed cell morphology and atypical immunophenotype. These findings may have implications for evaluating variation in both disease course and response to emerging therapies.

Aged↗

UK NEQAS for leucocyte immunophenotyping: the first 10 years.

In the past decade, cellular immunophenotyping has become a new discipline in diagnostic haematology and immunology, and is invaluable in the rapid diagnosis of leukaemia and monitoring disease progression in human immunodeficiency virus infected individuals. The introduction of bench top flow cytometers has meant that immunophenotyping is now also used for the quantitation of CD34(+) peripheral blood stem cells (PBSCs) to ensure the correct timing and adequacy of haematopoietic progenitor cell harvests. Furthermore, flow cytometry has become an important tool for the counting of leucocytes in blood components after leucocyte depletion. Because this new discipline is now such a major diagnostic and prognostic tool in the clinical arena, its use must be subject to both internal and external quality control. Such a requirement was first recognised as early as 1986 when an Inter-Regional Quality Assessment Scheme (IRQAS) was initiated for laboratories that undertook the immunocytochemical diagnosis of leukaemia using the alkaline phosphates anti-alkaline phosphatase technique. This programme began with around 25 UK laboratories. In 1990, after the introduction of two more programmes (one for leukaemia diagnosis using UV microscopy and latterly flow cytometry, and one for the enumeration of CD4(+) T cells) the IRQAS achieved UK National External Quality Assessment Scheme (UK NEQAS) status and changed its title to UK NEQAS for Leucocyte Immunophenotyping. In the past decade the once small IRQAS programme has evolved into the largest international scheme of its kind, providing EQA to over 650 laboratories world wide for leukaemia immunophenotyping, lymphocyte subset analysis, PBSCs, and more recently low level leucocyte counting. Over the years, this EQA programme has highlighted important problems, such as the inappropriate use of fluorochromes and antibody titre, and the identification of effective gating strategies, all of which have contributed directly to the high interlaboratory variations seen in cellular immunophenotyping. Furthermore, particularly in absolute counting of lymphocyte subsets, PBSCs, and the enumeration of low numbers of leucocytes, UK NEQAS for Leucocyte Immunophenotyping programmes have been instrumental in highlighting the differences that occur between single and dual platform flow cytometric technologies. As a result of these findings, UK NEQAS for Leucocyte Immunophenotyping has helped to reduce the variation seen on an interlaboratory basis and enabled greater standardisation both in the UK and internationally. These advances have been attributable to the development, by UK NEQAS for Leucocyte Immunophenotyping, of a unique whole blood stabilising process that ensures the retention of the physical characteristics (both light scatter and antigenic profile) required of cells to ensure successful cellular immunophenotyping. This major technological advancement has enabled the distribution of specimens for EQA purposes on a global scale that have minimal matrix effect and behave in a manner identical to fresh blood for several months after stabilisation.

Antigens, CD34↗

Immunophenotypic analysis of non-Hodgkin's lymphomas in cytologic specimens: a correlative study of immunocytochemical and flow cytometric techniques.

Most Non-Hodgkin's lymphomas(NHL) can be accurately diagnosed and classified based on morphologic and immunophenotypic findings on cytologic specimens. Immunophenotyping can be accomplished via immunocytochemistry (IC) or flow cytometry (FC). We reviewed our experience with 98 cytology specimens (70 fine-needle aspirates [FNA] and 28 effusions) that were submitted for immunophenotyping utilizing both IC and FC between January 1992 and December 1997 for the diagnosis of NHL. Eighty-five percent of the cases were immunophenotyped by both techniques. Among these there were only two discrepancies between IC and FC, yielding a 98% correlation rate. Of the 98 cases, 11% could not be immunophenotyped by FC and 4% could not be immunophenotyped by IC. The advantage of IC is the preservation of cytomorphology, which results in the requirement for a lower number of neoplastic cells and a limited, targeted panel of antibodies. This is especially useful in predominantly necrotic lymphomas in which only a few well-preserved neoplastic cells may be present, rendering the specimen inadequate for immunophenotyping by FC. The advantages of FC are in the detection of a small population of monoclonal cells in a background of reactive cells (particularly useful in effusion samples in which the predominant cell population is often reactive T lymphocytes), increased diagnostic precision through evaluation of objective parameters, and the use of multiple markers with dual labelling. We conclude that IC and FC are both excellent methods for immunophenotyping of cytology specimens and can be used interchangeably depending on the institutional expertise and availability.

Biopsy, Needle↗

Genotypic analysis of diffuse, mixed cell lymphomas. Comparison with morphologic and immunophenotypic findings.

Malignant lymphoma, diffuse, mixed small and large cell type, as defined in the Working Formulation, is heterogeneous both morphologically and immunophenotypically and, in some cases, clonality may be difficult to determine. Because gene rearrangement analysis has been shown to be a sensitive method for determining clonality, the authors genotyped 20 cases and compared the results with histologic and immunophenotypic findings. Immunophenotypic studies demonstrated that all lesions were composed predominantly of T cells. In addition, in eight cases either a monoclonal B-cell population (five lesions) or an aberrant immunophenotype (two T, one B) was detected, supporting a malignant diagnosis. In seven of these eight lymphomas, genotypic analysis confirmed the presence of a population of clonal cells. One case with an abnormal T-cell phenotype was germline. In 12 cases the immunophenotypic results were uncertain (i.e., no clonal population or abnormal immunophenotype was identified). Genotypic analysis provided evidence of clonality in eight. In four cases with uncertain immunophenotypic results, a clonal population also could not be identified with the use of Southern blot analysis. Thus, the authors conclude that gene rearrangement analysis is a valuable tool in the study of diffuse mixed cell lymphomas and is complementary to immunophenotypic studies. In addition, the authors analyzed the major breakpoint region of the bcl-2 protooncogene on chromosome 18, either by Southern blot analysis and/or with the polymerase chain reaction. The authors identified the t(14;18)(q32;q21) translocation in seven B-cell lymphomas, five of which were not considered to be of follicular center cell type on the basis of morphologic findings. These results suggest that the histologic spectrum of follicular center cell lymphomas is greater than is appreciated in the literature.

Adult↗

Multiparameter immunophenotypic analysis of fine needle aspiration biopsies and other hematologic specimens by laser scanning cytometry.

OBJECTIVE: To test the new laboratory technology of laser scanning cytometry with respect to immunophenotyping of all types of hematologic and lymphoreticular specimens and particularly those of limited size, such as fine needle aspiration biopsies and hypocellular body fluids. STUDY DESIGN: Over the course of two years, 343 hematologic and lymphoreticular specimens of all types were immunophenotyped by laser scanning cytometry using methodologies modified from those of conventional flow cytometric immunophenotyping. Results for all cases were corroborated with histology and/or cytology and, for some cases, immunohistochemistry and/or flow cytometric immunophenotyping. RESULTS: Over 98% of the 343 cases were successfully immunophenotyped by laser scanning cytometry. These included many hypocellular specimens, such as 38 fine needle aspiration biopsies and 33 body fluid specimens. CONCLUSION: Laser scanning cytometry is a new laboratory technology with several significant advantages relative to flow cytometry for immunophenotypic analysis of hematologic malignancy. The laboratory techniques are simplified, and antibody usage is reduced by 80%. Even more important, full-panel immunophenotyping with multiple antibodies can be performed on specimens as small as 50,000 cells total, making the technology particularly relevant to cytopathology. After immunophenotypic analysis, specimens can be stained for light microscopic examination, and individual cells meeting user-defined antigenic or physical characteristics can be automatically relocalized.

Adult↗