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Biomedical subjects

G Pizzolo

Publications and source records attributed to G Pizzolo.

At least 91 records · Page 5Linked to original sources
PubMed1992

The interleukin-2/interleukin-2 receptor system: structural, immunological, and clinical features.

Interleukin-2 (IL-2) has been the first and more extensively studied cytokine, in particular for its central role in the mechanisms of cell growth and differentiation. The function of IL-2 is mediated through specific receptors (IL-2R) present on the membrane of reacting cells. Using hybridoma and recombinant DNA technologies, both IL-2 and IL-2R have been biochemically characterized and purified and are available for in vitro and in vivo studies. The biological and clinical investigations on IL-2/IL-2R system have contributed to opening new avenues for the comprehension of phenomena that are critically important for biology, immunology and medicine.

Cell Membrane↗
PubMed1992

Neoplastic epithelial cells in a subset of human thymomas express the B cell-associated CD20 antigen.

A series of 36 human thymomas have been immunohistochemically analyzed using a panel of antibodies recognizing B-cell markers including CD20. Most thymomas exhibiting the cortical pattern, according to the criteria of Marino and Muller-Hermelink, were characterized by areas of medullary differentiation containing variable numbers of CD20+ B lymphocytes, thus mimicking the medulla of normal thymus. On the other hand, B cells were absent or rare in thymomas recognized as mixed using the same morphological criteria. Surprisingly, we observed in most mixed thymomas variable numbers of CD20+ spindle cells, characterized by long slender processes. Using double-marker analysis we could demonstrate the epithelial nature of these cells (expression of keratin and lack of lymphoid and B-cell-related markers). The immunoreactivity of thymoma epithelial cells with L26, an antibody widely used in the characterization of B-cell lymphomas, can represent a drawback of practical relevance in the differential diagnosis of mediastinal tumors.

Antibodies, Monoclonal↗
PubMed1992

The CD4 molecule belongs to the phenotypic repertoire of most cases of acute myeloid leukemia.

In the present study fresh leukemic cells obtained from 23 patients with acute myeloid leukemia (AML; FAB subtypes: three M1, five M2, two M3, five M4, eight M5) were investigated for the membrane expression of the CD4 molecule by cytofluorimetric analysis with an anti-CD4 monoclonal antibody (mAb). In 15 cases the presence of the CD4 mRNA was also investigated using Northern blot analysis. Membrane expression of the CD4 molecule was demonstrated in 19 out of 23 cases, and it was found to be weaker than in CD4+ lymphocytes and monocytes obtained from normal controls. Full-length CD4 mRNA was detected in 12 out of 15 (80%) cases, and AML cells positive for CD4 mRNA expression also expressed the CD4 antigen. Since the CD4 molecule expressed by T cells is associated with p56lck, a member of the src family of intracellular tyrosine kinases, we investigated whether the CD4 molecule expressed by myeloid blasts is also associated with a tyrosine kinase activity. In vitro kinase assays performed on anti-CD4 immunoprecipitates from lysates of myeloid leukemia cells from four CD4+ cases were negative for the presence of a tyrosine kinase activity. This finding was not due to the lack of expression of members of the src family since we were able to detect at least p60src and p59fyn in myeloid leukemia cells. According to our results, the CD4 molecule seems to belong to the phenotypic repertoire of most AML, irrespective of their FAB subtypes. However, in myeloid blasts this molecule is not associated with a tyrosine kinase activity as it occurs in T lymphocytes.

Blotting, Northern↗
PubMed1991

Evidence of c-myc gene abnormalities in mediastinal large B-cell lymphoma of young adult age.

Six cases of mediastinal large B-cell lymphoma (MLCL) with sclerosis were analyzed for the presence and patterns of c-myc and bcl-2 loci rearrangements, and for the presence of Epstein-Barr virus DNA sequences by Southern blot hybridization, c-myc gene alterations were found in three of six cases. Two cases showed the presence of mutations or small rearrangements at the 3' end of the first exon. The c-myc gene abnormalities found in these two cases are similar to those observed in the translocation 8;14 of the endemic Burkitt's lymphomas or in its variants t(2;8) and t(8;22). A third case showed a major rearrangement of c-myc gene, with truncation within its first intron, similar to those observed in sporadic Burkitt's and in acquired immunodeficiency-associated lymphomas. None of the cases displayed bcl-2 gene rearrangements or contained viral sequences. Our data suggest a possible role for a translocation-mediated c-myc activation in the pathogenesis of MLCL. Conversely, bcl-2 gene and Epstein-Barr virus do not appear to be involved in the pathogenesis of these peculiar lymphomas. The association between c-myc structural modifications and MLCL also seems to be of relevance in light of the peculiar tendency of this tumor to involve unusual extranodal site (eg, kidney), reminiscent of the spreading attitude of Burkitt's limphomas.

Adult↗
PubMed1991

Shedding of the soluble form of the CD8 complex by CD8+/HLA-DR+ cells in HIV-1-infected patients.

High levels of the soluble form of the CD8 molecule (sCD8) are detectable in the serum of HIV-1-infected patients. To investigate the mechanisms accountable for the release of this molecule we evaluated the presence of sCD8 in the supernatants obtained from in vitro cultures of highly purified CD8 cells isolated from 20 HIV-1-infected patients. At resting conditions cultured CD8 cells from HIV-1-infected patients released low amounts of sCD8; no statistically significant differences were observed between unstimulated cultures from HIV-1-seropositive patients and from HIV-1-seronegative subjects at risk for HIV-1 infection or normal healthy controls. Following in vitro activation of highly purified CD8 cells with a series of stimulatory agents, including phorbol myristate acetate, phytohemagglutinin (PHA) and recombinant interleukin-2, CD8 cells of HIV-1-infected patients significantly increased the shedding of sCD8. By expressing the results of activation-related release index (ARRI = sCD8 levels detected in the cultures with stimulatory agent/sCD8 levels detected in the unstimulated cultures), significantly higher values were observed upon PHA stimulation in HIV-1-infected patients than in control subjects. In order to identify the cell subset responsible for the enhanced release of sCD8 by PHA-stimulated cultures, we correlated the amounts of sCD8 detected in the supernatants with the phenotypic profile of CD8+ cells recovered from the cultures. A significant relationship was demonstrated between the percentage of CD8+/HLA-DR+ lymphocytes and sCD8 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Tumor necrosis factor-alpha and B-cell growth factor induce leukemic hairy cells to proliferate in vitro.

To clarify the mechanisms accounting for the hairy cell proliferation, in five patients with hairy cell leukemia (HCL), we evaluated the ability of neoplastic cells to proliferate in vitro in response to tumor necrosis factor-alpha (TNF-alpha), B-cell growth factor (BCGF), and interleukin 4 (IL-4). In addition, supernatants recovered from cultures of unstimulated hairy cells were tested for the capability to induce the proliferation of allogeneic hairy cells. We demonstrated that TNF-alpha and BCGF were able to induce the in vitro growth of hairy cells (stimulation index (SI) ranging, at different concentrations, from 1.6 to 10.7 and from 1.6 to 25.1 for TNF-alpha and BCGF, respectively). IL-4 did not show any proliferative effect on hairy cells. When unstimulated hairy cell supernatants were tested for the proliferative activity on allogeneic hairy cells, we demonstrated a low proliferative effect that was not inhibited by an anti-TNF-alpha antibody. Our findings demonstrate that unstimulated hairy cells proliferate in vitro in response to TNF-alpha and BCGF, thus suggesting that these cytokines could be involved in an autocrine model of cell proliferation.

Cell Division↗
PubMed1991

Different mechanisms of activation of proliferating CD3+ cells in patients with lymphoproliferative disease of granular lymphocytes.

To investigate the role of p55 and p75 chains of interleukin-2 receptor (IL-2R) on the activation of granular lymphocytes (GL) in patients with lymphoproliferative disease of granular lymphocytes (LDGL), the cells obtained from 11 LDGL patients (belonging to the CD3+ group) were studied for (a) the surface expression and (b) mRNA transcripts of the p55 and p75 IL-2R after activation with anti-CD3 monoclonal antibody (mAb) or interleukin-2 (IL-2). The effects of mAbs specifically blocking the p55 and p75 IL-2R on the generation of proliferative and cytotoxic functions were studied following anti-CD3 mAb stimulation. A significant difference was observed in the expression of p55 and p75 antigens on LDGL cells under resting conditions: a low number of p55 IL-2R+ (mean 1.2 +/- 0.4%) and high values of p75 IL-2R+ cells (54.9 +/- 7.4%). Accordingly, a barely detectable message for the p55 IL-2R and a strong signal for the p75 IL-2R mRNA were demonstrated. Following activation with anti-CD3 or IL-2, different patterns of IL-2R expression were observed. Anti-CD3 mAb induced an increase in the expression of the p55 IL-2R both at the mRNA and antigen level, whereas the p75 values remained consistently raised. In contrast, IL-2 induced the expression of p55 IL-2R mRNA associated with only a slight expression of this antigen. This finding was associated with a decrease in the cell expression of the p75 IL-2R, whereas the amount of p75 mRNA was unchanged. Both anti-CD3 mAb and IL-2 induced cell proliferation and cytotoxicity against the K-562 target cells. Anti-p55 IL-2R mAb did not affect the cytotoxic activity mediated by anti-CD3, but it markedly inhibited cell proliferation. Anti-p75 mAb did not inhibit either lytic function or cell proliferation mediated by anti-CD3 mAb, suggesting that only the high affinity IL-2R (p55 plus p75) is involved in anti-CD3 mediated cell activation in LDGL patients. This mechanism is different from that responsible for the IL-2 activation of CD3+ GL in LDGL patients, which is achieved through the p75 IL-2R alone. These results provide new insights into the pathophysiology of proliferating GL in LDGL patients and may also contribute to further characterization of the normal CD3+ GL population.

Adult↗
PubMed1990

Cell membrane expression and functional role of the p75 subunit of interleukin-2 receptor in lymphoproliferative disease of granular lymphocytes.

The cell membrane expression and functional role of the interleukin-2 receptor (IL-2R) was analyzed in nine patients with lymphoproliferative disease of granular lymphocytes (LDGL) using monoclonal antibodies (MoAbs) specific for the p75 (TU27) and the p55 (anti-Tac) subunits of IL-2R. Four patients were characterized by the proliferation of CD3+CD8+ granular lymphocytes (GL) expressing the alpha/beta T-cell receptor (T alpha beta) and one case by the proliferation of CD3+CD4-CD8- GL expressing the gamma/delta T-cell receptor (T gamma delta); in four additional cases proliferating cells were CD3 negative GL. Consistent with data observed on normal GL, phenotypic analysis demonstrated that patients' GL lack the expression of the p55 IL-2R, whereas the p75 subunit is constitutionally expressed by expanding GL of both T-cell (either T alpha beta and T gamma delta) and natural killer (NK) origin in variable proportions (11% to 94% of cells). The analysis of the cytotoxic and proliferative activity demonstrated that the anti-p55 MoAb failed to inhibit IL-2-mediated activation, whereas a marked inhibition of both cytotoxicity and proliferation were obtained using the anti-p75 chain specific MoAb. These data indicate that the p75 chain of IL-2R is responsible for IL-2 signal transduction in both CD3+ and CD3- LDGL patients' GL.

Adult↗
PubMed1990

Immunohistochemical differentiation of follicular lymphoma from florid reactive follicular hyperplasia with monoclonal antibodies reactive on paraffin sections.

In this study monoclonal antibodies which recognize lymphoid-associated antigens on paraffin sections (LN1, MB2, L26, MT2, UCHL1) have been evaluated to assess their usefulness in the distinction between reactive and neoplastic lesions of lymphoid follicles. Thirty-three follicular lymphoma samples and 36 reactive samples (lymph nodes and tonsils) were analyzed. MT2 appeared as the most valuable immunophenotypic marker as emerged from a comprehensive quantitative evaluation of 2329 reactive follicles and 2288 neoplastic follicles performed on MT2 immunostained sections. MT2-positive follicles were found in all lymphoma samples but one. Overall 1908 of 2288 neoplastic follicles were judged as positive whereas no follicles with comparable strong MT2 immunoreactivity could be found in non neoplastic samples. These latter showed weak MT2 positivity only in about 10% (224/2329) of reactive follicles. This study confirms that MT2 follicular positivity can be considered a reliable marker of follicular neoplasia, although negative results ought to be considered with caution. The detection of centrofollicular cells outside the germinal centers, which is considered a reliable criterion of follicular neoplasia, was highly improved by LN1 immunostaining. On the other hand pan-B antibodies such as L26 and MB2 were less informative because of the large number of B-lymphocytes observed in interfollicular areas of nonneoplastic samples.

Adult↗
PubMed1990

Mechanisms accounting for the defective natural killer activity in patients with hairy cell leukemia.

Natural killer (NK) cell activity is severely impaired in untreated patients with hairy cell leukemia (HCL). In an attempt to investigate whether this impairment is related to a defect at the target cell binding and/or at the post target cell binding level, we evaluated the peripheral blood mononuclear cells (PBMC) of HCL patients for their ability to: (1) bind and kill K-562 NK-sensitive targets at the single cell binding level; (2) release the NK cytotoxic factor (NKCF) under different in vitro stimuli, including K-562 and phytohemoagglutinin; and (3) kill K-562 targets in a lectin-dependent cellular cytoxicity (LDCC) assay. This study demonstrates that untreated HCL patients' PBMC show a low ability to form conjugates with K-562 targets at the single cell binding level (5.7% +/- 1.0%) with respect to patients studied after treatment (9.3% +/- 1.3%) and controls (15.0% +/- 4.0%); P less than .05 and P less than .001, respectively. A decreased ability to kill the bound target was demonstrated in untreated cases (1.2% +/- 1.1%) versus patients studied after treatment and controls (12.3% +/- 1.6%, 17.0% +/- 3.1% respectively); P less than .001 in both conditions. After activation of effector cells with interleukin-2 (IL-2) in vitro, an increase in the ability of PBMC to form conjugates with K-562 targets and kill the bound target was demonstrated in each group of patients. Moreover, IL-2 was able to increase the cytotoxicity against NK-sensitive targets in all patients tested. Evaluation of NKCF production showed that untreated patients release low levels of NKCF when PBMC were incubated in the presence of K-562 stimulators (1.8% +/- 0.7%) with respect to patients after interferon-alpha (IFN-alpha) therapy (7.6% +/- 2.1%) and controls (12.9% +/- 2.2%); P less than .02 and P less than .001, respectively. When the recognition mechanisms were bypassed by triggering the cells with lectins in an LDCC assay, we demonstrated an increase of the lytic activity in both groups of patients with respect to the baseline values. However, the cytotoxic capacity observed in untreated patients was significantly lower than that observed in subjects after IFN-alpha therapy and controls (P less than .001). These findings suggest that the impaired NK activity observed in patients with HCL is related to defects both at the target and posttarget cell binding levels.

Adult↗
PubMed1990

Expression and gene rearrangement of the T-cell receptor in human thymomas.

Human thymomas are epithelial neoplasms frequently associated with an exuberant lymphoid component. This mixture of epithelial cells and lymphocytes closely mimicks the organization of normal thymic cortex. However, it is not known whether thymocytes in thymoma express the T-cell receptor (TCR) for the antigen. We have analyzed the molecular configuration of TCR genes and their phenotypic expression in eight thymomas. In all we detected polyclonal rearrangements of TCR genes and cytoplasmic expression of TCR molecules in most thymocytes, thus indicating that rearranged TCR genes in thymomas are functioning genes. In addition, these findings suggest that the epithelial component of thymomas, even if neoplastic, is still capable of directing thymocyte differentiation.

Adolescent↗
PubMed1990

Serum levels of soluble CD30 molecule (Ki-1 antigen) in Hodgkin's disease: relationship with disease activity and clinical stage.

In all cases of Hodgkin's disease (HD) Reed-Sternberg (RS) cells express the CD30 antigen. It has been recently demonstrated that this molecule can be released from the cell membrane of CD30+ neoplastic cells in a soluble form (sCD30), detectable in culture supernatants and body fluids. In this paper we investigated by an immunoassay the serum levels of sCD30 in 58 patients with HD, in order to define the possible relationship of this molecule to the clinical and pathological findings. sCD30 molecule was found at detectable levels in 24 out of 50 patients (48%) with active disease, whereas it was always absent in control sera and in cases in complete remission. Among the patients with active HD, the incidence and mean values of detectable levels (+/- SEM) of sCD30 were higher in cases with progressive or relapsing disease (61.5%, mean 458 +/- 190 U/ml) as compared to those at presentation (43.2%, mean 116 +/- 33 U/ml). Among the cases at presentation, detectable levels were observed more often in patients with advanced stages (III + IV: 61%) and constitutional symptoms ('B': 61.5%) than in early stages (I + II: 26%) and without symptoms ('A': 33.3%). In addition, higher mean values were found in stages III + IV (182 +/- 60 U/ml) and in 'B' cases (208 +/- 73 U/ml) than in stages I + II (65 +/- 30 U/ml) or 'A' patients (64 +/- 26 U/ml). The above findings suggest a possible role for the sCD30 as a tumour marker in HD.

Adolescent↗