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PubMed2004

Dissociation of CD4(+) cell counts from viral load and association with immune complexes in HIV(+) hemophilia patients.

OBJECTIVE: We have postulated that the host autoimmune response regulates and mediates CD4 depletion during HIV infection by opsonization of circulating CD4(+) lymphocytes carrying autoreactive immune complexes (IC) consisting of complement-fixing IgM and IgG, and during advanced stages of HIV disease of IgM/ IgG/gp120 complexes. In this retrospective study, we investigated whether HIV causes CD4 depletion by direct cytotoxicity or indirectly by induction of a host autoimmune response. PATIENTS AND METHODS: In 1996, 12 HIV(+) hemophilia patients were converted to highly active antiretroviral therapy (HAART), while 10 other patients were maintained on conventional antiretroviral treatment and another 11 patients refused to be treated with antiretroviral drugs. The host immune response of these 33 HIV(+) patients was studied during the periods of minimum viral replication (Interval 1), subsequent rise in viral replication with strong replication dynamic (Interval 2), and maximum viral replication (Interval 3). The patients were categorized into three groups according to viral load (VL). Group A: patients with low level VL (n=10) showed a modest increase from <80 to <4 log 10 HIV-1 RNA copies per milliliter plasma during the observation period; Group B: patients with medium level VL (n=12) showed a stronger increase from <80 to >4 log 10 copies per milliliter plasma; and Group C: patients with high level VL (n=11) consistently had a median of >4 log 10 copies per milliliter plasma, during Intervals 1-3, with the exception of one patient who during Interval 2 had 4800 copies per milliliter. Blood lymphocyte subpopulations, proportions of CD4(+) blood lymphocytes coated with IgM, IgG, C3d and/or gp120, in vitro responses to mitogens and pooled allogeneic stimulator cells, as well as numbers of HIV-1 RNA copies per milliliter plasma were measured. RESULTS: Sequential analysis of VL, IC load on CD4(+) blood lymphocytes and CD4 counts showed that an increasing VL was not associated with CD4 depletion, when the proportion of IC-coated circulating CD4(+) blood lymphocytes remained stable. When, CD4 counts and IC load were analyzed during corresponding intervals of retroviral replication in the three patient groups, a higher VL was associated with lower CD4 counts only when the IC load (IgG or gp120/IgG) on CD4(+) lymphocytes was higher as well. CONCLUSION: These data suggest that HIV regulates and mediates CD4 depletion in part by the induction of autoreactive ICs against CD4(+) lymphocytes, especially complement-fixing autoreactive IgG and gp120/IgG complexes.

CD4 Antigens↗
PubMed1978

The sequential appearance of Ia-like antigens and two different complement receptors during the maturation of human neutrophils.

Ia antigens and two different types of complement (C) receptors appeared on membrane surfaces in a distinct sequence during the maturation of human neutrophils. Taking advantage of the finding that neutrophil celll density increased with maturation, density gradient centrifugation was used to separate neutrophils into fractions that were greatly enriched in cells representing individual stages of differentiation. Myeloblasts, the earliest cells recognized in the myeloid series of both normal and myelogenous leukemic individuals, expressed Ia determinants, whereas Ia determinants were absent or diminished on the majority of promyelocytes and completely undetectable on more mature granulocytes. Double marker studies demonstrated that Ia determinants were lost from the membrane of developing myeloid cells before the appearance of any type of C receptor. In the next phase of maturation defined by surface markers, neutrophils acquired a CR2-type C receptor (C3d receptor) that was similar in specificity to CR2 of B lymphocytes. This stage of maturation approximately corresponded to the myelocyte-metamyelocyte stage defined by standard morphologic criteria, and preceded the third stage of surface marker maturation when developing neutrophils began to express CR1-type C receptors (immune adherence, C4b-C3b receptors) in addition to CR2. In the final stage of surface marker-defined maturation, CR2 was lost from high density polymorphonuclear neutrophils and CR1 was maximally expressed. Normal blood polymorphonuclear neutrophils contained only 17% of CR2-bearing cells and these were shown to be of lower density than the majority of neutrophils that expressed only CR1. There was some variation in the correlation of surface marker expression and maturation stage defined by morphologic criteria, but in all cases the sequence of marker appearance was the same: Ia leads to CR2 leads to CR1CR2 leads to CR1.

Binding Sites↗
PubMed1991

[Controlled immunoglobulin therapy in immune hemolytic anemia by positive pool immunoglobulin fluorescence test].

An Italian boy with homozygous beta-thalassemia showed a shortening of transfusion intervals at the age of three years. He had a positive direct antiglobulin test (DAT) because of C3d-loaded red blood cells without any detectable erythrocytic antibody. Serologic investigations indicated a recent EBV infection. Pool immunoglobulin fluorescence test (PIT) revealed a loading of red blood cell membranes with antigens. Oral prednisone therapy did not show any effect. After a single infusion of 400 mg immunoglobulin per kg body weight decrease of hemoglobin concentration slowed down to the rate before crisis. DAT and PIT became negative. The immune hemolytic crisis was possibly due to erythrocyte loading with EBV antigen that caused activation of the alternate complement pathway. Detection of antigen loaded red blood cells by PIT suggested a immunoglobulin therapy in order to coat the structures promoting hemolysis. Thus, a positive PIT seems to be a criterion for successful application of immunoglobulins in immune hemolytic anemia.

Anemia, Hemolytic, Autoimmune↗
PubMed1991

Adherence and receptor relationships of Candida albicans.

The cell surface of Candida albicans is composed of a variety of polysaccharides such as glucan, chitin, and mannan. The first two components primarily provide structure, while the mannan, often covalently linked to protein, constitutes the major antigen of the organism. Mannoproteins also have enzymatic activity (acid protease) and ligand-receptor functions. The complement receptors of C. albicans appear to be mannoproteins that are required for the adherence of the organism to endothelial cells. This is certainly true of the CR3-like protein of C. albicans. Proof that the CR3 is the Candida receptor for endothelial cells is derived from two observations. First, mutants lacking CR3 activity are less adherent in vitro and, in fact, less virulent. Second, the ligand recognized by the CR3 receptor (C3bi) as well as anti-CR3 antibodies blocks adherence of the organism to endothelial cells. The CR2 of C. albicans appears to promote the adherence of the organism to plastic substrates. Unlike the CR2 of mammalian cells, the Candida CR2 recognizes ligands containing the RGD sequence of amino acids in addition to the C3d ligand, which does not contain the RGD sequence. There is uncertainty as to whether the Candida CR2 and CR3 are, in fact, different proteins. A mannoprotein has also been described as the adhesin for epithelial cells. In this case, the receptor has a lectinlike activity and recognizes fucose- or glucosamine-containing glycoproteins of epithelial cells, depending on the strain of C. albicans. The oligosaccharide component of the receptor is probably not involved in ligand recognition and may serve to stabilize the receptor. However, the oligosaccharide factor 6 epitope of mannan may also provide adhesin activity in the recognition of epithelial cells. Mannoproteins can be extracted from cells by a number of reagents. Zymolyase, for instance, tends to remove structural mannoproteins, which contain relatively little protein and are linked to glucan. Reagents such as dithiothreitol, on the other hand, tend to extract mannoproteins containing higher amounts of protein that appear to have receptor function. The mannoproteins of C. albicans are dynamically expressed and may be growth phase and growth form specific.

Candida albicans↗
PubMed1994

Further evidence for involvement of both cell mediated and humoral immunity in generalized vitiligo.

Immunohistochemical and immunoserological evidence supports the involvement of both cell-mediated and humoral mechanisms in the pathogenesis of melanocyte destruction in vitiligo. Punch biopsies from depigmented vitiliginous skin (VS), normal-looking pigmented skin (PS), and marginal skin (MS) from patients with generalized vitiligo (n = 15) were labeled with K 1.2.58, OKM1 (CD11b), Leu 11b (CD16), Leu 19 (CD56), IFN-gamma receptor, IL-2 receptor (CD25), IgG, IgM, C3c, and C3d MoAbs. In addition, in vitro effects of vitiligo sera (n = 13) on human newborn melanocytes (HMel) under different culture conditions were studied. The immunohistochemical findings showed absence of K 1.2.58+ epidermal melanocytes in VS and abnormal morphology in MS. In these areas, a few CD11b+ cells in the dermis and epidermis could be detected but no significant numbers of CD16+ or CD56+ cells were seen among the mononuclear cellular infiltrate. IL-2 and IFN-gamma receptors were clearly expressed by the cellular infiltrate. No significant deposition of complement or immunoglobulin was seen. The addition of vitiligo sera to HMel cultures induced a significant cellular proliferation. The stimulation of cell proliferation occurred regardless whether the sera were added alone or when preheated (56 degrees C for 1 hr) and then supplemented with a complement source (P < 0.01 at 2%, P < 0.001 at 10%, and P < 0.01 at 20% for sera alone) (P > 0.05 at 2%, P < 0.05 at 10%, and P < 0.01 at 20% for decomplemented sera plus complement).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1978

Characterization of mononuclear cell infiltrates in psoriatic lesions.

The dermal mononuclear cell infiltrates of psoriatic lesions were characterized by receptors for sheep erythrocytes (T-lymphocytes), C3b receptors (macrophages and B-lymphocytes) and C3d receptors (B-lymphocytes), using hemadsorption to cryostat sections in a closed chamber. T-lymphocytes and macrophages were the predominant inflammatory cells. Very few B-lymphocytes were detected. These findings are discussed in relation to the possible pathogenetic signficance of cellular immunity in psoriasis.

B-Lymphocytes↗
PubMed1992

Influence of serotype of group B streptococci on C3 degradation.

Serotype III strains of group B streptococci (GBS) are isolated from the majority of young infants with bacteremia or meningitis. We hypothesized that serotype-associated differences in structure of the type-specific capsular polysaccharide or the presence of c protein would influence the extent to which C3 degradation occurs on GBS and that type-specific antibody would alter C3 deposition or degradation patterns. When clinical isolates of GBS representing serotypes Ia, Ib/c, II (with or without c protein) and III were employed with hypogammaglobulinemic serum as an opsonic source, a remarkable similarity was observed in patterns of C3 deposition and degradation for each of the four GBS serotypes and between strains with or without c protein. Both C3b and iC3b were detected by 5 min and throughout a 90-min opsonization interval. Less deposition occurred at 5 min on serotypes Ia and Ib/c than on types II and III GBS. Minimal degradation to C3d or smaller fragments was observed. Type-specific antibody facilitated C3b deposition on GBS and C3b degradation to iC3b early in opsonization. Possibly, accessibility of C3 fragments to neutrophil receptors, rather than the extent to which the surface permits C3 degradation, accounts for differential virulence among GBS serotypes.

Antibodies, Bacterial↗
PubMed1986

Performance and biocompatibility of a new hemodialysis membrane.

Performance studies and investigations of the biocompatibility of a new hemodialysis membrane were conducted in patients being chronically hemodialyzed. The investigated polycarbonate membrane revealed a very satisfying performance with regard to clearance values and the ultrafiltration rate. The biocompatibility studies showed a significant leukopenia and an increase of C5a, platelet factor 4 and granulocyte elastase. Thrombocytes and C3d remained unchanged. Long-term studies have to confirm whether or not the new membrane is more biocompatible, a suggestion which could be advanced, as no febrile episodes were observed during any treatment, a finding which is not typical for Cuprophan hemodialysis.

Biocompatible Materials↗
PubMed1990

Neoantigens in complement component C3 as detected by monoclonal antibodies. Mapping of the recognized epitopes by synthetic peptides.

The different fragments of the third complement component, C3, generated upon complement activation/inactivation have the ability to bind to several other complement components and receptors as well as to proteins of foreign origin. These multiple reactivities of C3 fragments are associated with a series of conformational changes occurring in the C3 molecule during its degradation. The conformations acquired by the different C3 fragments are also associated with the exposure of neoantigenic epitopes that are specific for (a) particular fragment(s). In order to study these epitopes and thus the conformational changes occurring in C3, monoclonal antibodies (mAbs) recognizing such epitopes were produced in Balb/c mice after immunization with denatured human C3. Two of the three antibodies (7D84.1 and 7D264.6) presented in this study recognized predominantly surface-bound iC3b, and one mAb (7D323.1) recognized both surface-bound and fluid-phase iC3b. Although none of the mAbs recognized any other fluid-phase C3 fragment, all three antibodies detected micro-titre-plate-fixed C3b and iC3b, but not C3c or C3d. In addition to the reaction with human C3, mAb 7D323.1 also bound to micro-titre-plate-fixed rabbit C3. The epitopes recognized by the three mAbs were further localized by using synthetic peptides that were designed on the basis of the differential binding of the mAbs to the C3 fragments. All three antibodies reacted with C3-(924-965)-peptide, which represents the region of C3 between the kallikrein-cleavage site (923-924) and the elastase-cleavage site (965-966). On the basis of the binding of the mAbs to five different overlapping peptides spanning the region between residues 924 and 965 of the human C3 sequence, and the sequence similarity between human C3 and rabbit C3 within this area, the epitopes recognized by these antibodies are mapped. The contribution of the individual amino acid residues in the formation of the epitopes is discussed.

Antibodies, Monoclonal↗
PubMed1990

Epstein-Barr virus receptor expression on human CD8+ (cytotoxic/suppressor) T lymphocytes.

In 1977 we showed that cells of a human lymphocytic leukaemia-derived T line (Molt-4) have receptors for Epstein-Barr virus (EBV). More recently, EBV-positive human T cell lymphomas have been recognized and human T cell lines containing the EBV genome have been established in vitro. To understand better the interaction of EBV with T cells, we decided to determine first whether human peripheral blood T lymphocytes express receptors for EBV. Using flow cytometry we examined the binding of both lymphocyte-transforming (B95-8) and non-transforming (P3HR-1) strains of EBV to T lymphocyte subpopulations, using a double labelling technique with T cell-specific phycoerythrinated monoclonal antibodies (Leu 2a) and fluoresceinated viral preparation. Our results suggest that, in general, about 50% of the CD8+ (or suppressor/cytotoxic) T cell subpopulation from both EBV-seropositive and -seronegative individuals can bind EBV. EBV receptor expression on these T cells was about 10 and 51 times less than that on Molt-4 and Raji (an EBV receptor-positive B cell line) cells, respectively. The specificity of this binding was demonstrated by the inhibition of attachment of viral preparations preincubated with a monoclonal antibody directed against the viral ligand (gp240/350), and by preincubating these target T cells with unlabelled virus. We were unable to detect EBV-induced antigens in infected T cells, suggesting that, as in Molt-4 cells, virus internalization may not occur in fresh T cells and/or that the virus receptor may not be completely functional. We were also unable to detect C3d (or CR2) receptors on these T cells, or to inhibit virus attachment by treating the targets with an anti-CR2 monoclonal antibody (OKB7), suggesting that the EBV receptor on CD8+ peripheral blood lymphocytes is different from that on B cells.

Cell Line↗
PubMed1991

Autoantibodies against CD4 cells are associated with CD4 helper defects in human immunodeficiency virus-infected patients.

To investigate whether autoantibodies against CD4-positive lymphocytes might induce helper dysfunction, autoantibody formation and T-cell function was examined simultaneously in 61 hemophilia patients. Twenty patients were human immunodeficiency virus (HIV)-negative, 26 HIV-positive stage CDC II or III, and 15 were HIV-positive stage CDC IV. T lymphocytes, CD4-positive, or CD8-positive T subsets were cocultured with B lymphocytes and pokeweed mitogen (PWM) for 6 days and Ig-secreting cells were assessed in a reverse hemolytic plaque assay. The presence of IgM, IgG, C3d, or gp120 on the surface of T cells or T subsets was analyzed by flow cytometry. Autoantibodies against CD4-positive T cells were not detected in controls or HIV-negative patients, but were common in HIV-positive patients (20 of 41 patients). In patients with autoantibodies we found an increased incidence of CD4 helper defects (P less than .0001 in CDC II or III patients; P less than .02 in CDC IV patients). 12 of 13 patients with IgM autoantibodies and 4 of 4 with IgG autoantibodies showed CD4 helper defects. Complement fixation had no relevance. Autoantibody formation against CD4 cells was not due to increased in vivo B-cell stimulation (spontaneous plaque formation: 611 +/- 204 PFC/10(6) B cells in autoantibody-negative patients v 650 +/- 202 PFC/10(6) B cells in autoantibody-positive patients; not significant). Thus, our results suggest that autoantibody formation is not caused by a general state of in vivo B-cell activation. Rather, the production of autoantibodies appears to coincide with defects in B-cell proliferation or differentiation, as shown by reduced mitogen-stimulated B-cell responses in CDC II and III patients (P less than .05). Autoantibodies against CD4 cells appear to be involved in the pathogenesis of CD4 helper defects of HIV-infected patients.

Antigens, CD↗
PubMed1984

Adverse reactions in selected patients following intravenous infusions of gamma globulin.

Fifteen patients with hypogammaglobulinemia or agammaglobulinemia were treated with intravenous gamma globulin preparation over a 17-month period. The patients were selected for treatment if they had chronic antibody deficiency syndromes associated with increased susceptibility to infections. Levels of circulating immune complexes, C1q, C3, and C3d were determined in serum samples obtained before treatment and immediately following treatment with the gamma globulin. In every patient studied, circulating immune complexes were detectable in the postinfusion samples. Two patients had adverse reactions to the intravenous gamma globulin therapy. Analysis of the serum samples of both of these patients showed that one patient had an autoantibody to IgA and the other had an autoantibody to beta-lipoprotein. Both IgA and beta-lipoprotein were present in the intravenous gamma globulin preparations. Therefore, reaction with each of the autoantibodies by the antigens activated the complement system in vivo with production of split products of C3.

Adult↗
PubMed1998

Autoimmune hemolytic anemia caused by warm-reacting IgM-class antibodies.

Warm IgM autoantibodies occur in association with IgG-class and/or IgA-class immunoglobulins in approximately 30 percent of patients with warm-type autoimmune hemolysis. They may be classified as agglutinins or hemolysins, which may be incomplete or complete, depending on in vitro serology; they almost always bind complement. Autoimmune hemolytic anemia solely due to warm IgM autoantibodies is exceedingly rare. We report two cases of the incomplete agglutinin type. The autoantibodies were confirmed as IgM by their ability to rebind to normal red blood cells (RBCs) after elution; the absence of small increases in RBC-bound IgG and IgA was shown by a sensitive enzyme-linked antiglobulin test. Patient 1 was a 64-year-old female with non-Hodgkin's lymphoma, with a hemoglobin of 50 g/L and haptoglobin of < 0.1 g/L. Direct antiglobulin tests were positive for IgM, C3d, and C3c; only IgM was present in an eluate. The serum contained a weak autoantibody at 37 degrees C and tests for hemolysins were negative. The patient suffered chronic hemolysis and required intensive treatment, including splenectomy. Patient 2 was a 65-year-old female; the hemoglobin was 78 g/L and the haptoglobin was < 0.1 g/L. Direct antiglobulin tests were positive for IgM and C3d; an eluate contained only IgM. No free autoantibody was present in the serum and tests for hemolysins were negative. Two serious infections occurred and the hemolysis remained chronic, requiring continuous treatment during the 4 months she was followed.

Journal Article↗
PubMed1992

Conformational differences between surface-bound and fluid-phase complement-component-C3 fragments. Epitope mapping by cDNA expression.

In previous studies a subset of complement-component-C3 (C3) epitopes, C3(D), expressed in denatured and surface-bound C3 and C3 fragments, has been described. These epitopes were detected by antibodies raised against denatured C3. In the present study we used a cDNA expression strategy to localize epitopes recognized by monoclonal and polyclonal anti-C3(D) antibodies. First, DNAse I digestion of C3 cDNA was used to generate 200-300 bp fragments. These cDNA fragments were expressed as beta-galactosidase-C3 fusion proteins using the lambda gt11 vector. The fusion proteins were tested by Western-blot analysis for reactivity with monoclonal and polyclonal anti-C3 antibodies, and the location of the epitopes were determined by sequencing the cDNA fragments. Affinity-purified polyclonal anti-C3(D) antibodies specific for denatured C3 reacted strongly with the C3 fusion fragments corresponding to segments of the 40 kDa subunit of C3c (residues 1477-1510) and the C3d fragment (residues 1117-1155 and 1234-1294) of C3. Adsorption of the polyclonal antibodies with a mixture of EAC3b and EAC3bi (degradation fragments of C3 bound to sheep erythrocytes) abolished binding to fusion proteins spanning the C3d region, but not the 40 kDa fragment of C3c. No effect was seen with the corresponding soluble C3 fragments. The monoclonal anti-C3(D) antibodies (mAbs) 7D326.1 and 7D331.1, specific for EAC3b and EAC3bi, bound to a fusion protein corresponding to amino acid residues 1312-1404, whereas mAb 7D9.2, specific for EAC3d, reacted with a fusion protein spanning amino acid residues 1082-1118. mAbs 4SD11.1 and 4SD18.1, which did not bind to any physiological C3 fragment, detected a fusion protein covering residues 1477-1510. In summary, the segments of C3 represented by amino acid residues 1082-1118, 1117-1155, 1234-1294 and 1312-1404 accommodate C3(D) epitopes that are expressed by erythrocyte-bound C3 fragments, but not by the corresponding fluid-phase fragment, whereas the segments spanning residues 973-1026 and 1477-1510 contain C3(D) epitopes that are exposed exclusively in denatured C3 and therefore hidden in physiological fragments of the protein.

Animals↗
PubMed1984

Structure and function of the human C3b receptor.

The human C3b receptor (C3bR) is a glycoprotein that exists in two allotypic forms having Mr values of approximately 250,000 (F) and 260,000 (S). The number of receptors present on erythrocytes varies by eightfold among normal individuals and is genetically regulated by two codominant alleles that are distinct from the alleles determining the structural polymorphism. C5a and C5ades Arg induce rapid increases in the number of receptors expressed by neutrophils in vitro, and probably account for the increased receptor expression on neutrophils in patients undergoing hemodialysis. Cytoskeletal association of the C3bR on monocytes and neutrophils is suggested by experiments demonstrating receptor-mediated phagocytosis and adsorptive endocytosis through coated pits, and by the reciprocal coredistribution of cross-linked C3b and Fc receptors and the detergent insolubility of cross-linked C3bR. The factor H-like cofactor activity of the C3bR promotes the cleavage of bound C3b to iC3b, C3c, and C3d,g, which may enhance the clearance of circulating immune complexes and the generation of ligands for CR2 and CR3. The inherited partial deficiency of the erythrocyte C3bR in patients with systemic lupus erythematosus and the absence of glomerular C3bR in these patients with proliferative glomerulonephritis may contribute to systemic and organ-specific abnormalities in the clearance of immune complexes in this disease.

Complement C4↗
PubMed1983

C3 cleavage products stimulate release of prostaglandins by human mononuclear phagocytes in vitro.

Human monocytes cultured for up to 48 hr in serum-free, chemically defined culture media released low levels of prostaglandin. C3b, C3bi, and C3c stimulated an indomethacin-sensitive, dose-responsive increase in the amount of monocyte prostaglandin released by 18 hr after treatment. Native C3 and C3d, which do not bind to monocyte receptors, failed to stimulate increased prostaglandin release. Lymphocytes, treated and untreated, produced 10(-2) to 10(-3) as much prostaglandin as the monocytes. These data support the concept that monocytes are a significant source of leukocyte prostaglandin. They also introduce an important new biologic function for the C3 fragments C3b, C3bi, and C3c.

Cells, Cultured↗
PubMed1974

Binding of soluble immune complexes to human lymphoblastoid cells. II. Use of Raji cells to detect circulating immune complexes in animal and human sera.

Cells from a human lymphoblastoid cell line (Raji), with B-cell characteristics, and having receptors for human IgG Fc, C3b, and C3d, were used in an immunofluorescence test as in vitro detectors of immune complexes in animal and human sera. By this test, as little as 200-300 ng aggregated human gamma globulin or immune complexes per ml serum could be detected. The receptors for IgG Fc on the Raji cells were shown to be inefficient in detecting aggregated human gamma globulin and binding of aggregates to these receptors was inhibited by physiologic concentrations of 7S human IgG. Enhancement of aggregated human gamma globulin binding and binding of immune complexes formed in vitro to Raji cells was observed when the receptors for complement on these cells were used. By using the receptors for complement on Raji cells, circulating immune complexes were detected in rabbits with acute serum sickness, in mice with acute lymphocytic choriomeningitis virus infection, and in humans with immune complex type glomerulonephritis. The Raji cell test may be useful in detecting complement fixing immune complexes in different disease states, in monitoring circulating complexes in patients with immune complex diseases and in identifying the antigen(s) responsible for the induction of pathogenic immune complexes in humans and animals.

Animals↗
PubMed1978

B-cell lymphoma lacking Fc- and C3d-receptors.

Various cell surface markers were studied in a patient with lymphosarcoma cell leukemia. The B-cell derived feature of the neoplastic cells could be identified by demonstration of monoclonal surface immunoglobulin of IgM-kappa type of high density synthesized by the cells. Interestingly, there were no Fc- nor C3d-receptors demonstrable using various techniques. Only 22% of the leukemic cells expressed C3b receptors. The failure of rosette formation with mouse erythrocytes was an additional surface feature distinguishing from ordinary chronic lymphatic leukemia of the B cell type. The phenotype of the leukemia cells is discussed as corresponding to that of a less differentiated B lymphocyte.

B-Lymphocytes↗