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Biomedical subjects

A Poggi

Publications and source records attributed to A Poggi.

At least 109 records · Page 6Linked to original sources
PubMed1990

Platelet-derived mitogenic activity and bone marrow fibrosis in myeloproliferative disorders.

Mitogenic activity, measured as 3H-thymidine incorporation by NIH 3T3 cells, following stimulation with platelet-rich-plasma-derived serum (PRS), platelet-poor-plasma-derived serum and platelet extract was studied in 14 patients with myeloproliferative disorders (MPD) and 7 normal subjects. Reduced mitogenic activity was found in PRS and platelet extract of patients with MPD, as compared to controls. The average levels of platelet-derived growth factor (PDGF) equivalents were as follows: 16.3 +/- 7.2 pg/10(6) platelets in controls, 6.2 +/- 2.2 pg/10(6) (p less than 0.05) platelets in patients with polycythaemia vera, 1.8 +/- 0.4 pg/10(6) (p less than 0.01) platelets in patients with idiopathic myelofibrosis and 4.0 +/- 0.8 pg/10(6) (p less than 0.05) platelets in patients with essential thrombocythaemia (Dunnett test). A reduction of intraplatelet levels of beta-thromboglobulin, although not statistically significant, was found in the same patients. No apparent relation was found between the amount of PDGF equivalents and the degree of bone marrow fibrosis.

Adult↗
PubMed1990

Clonal analysis of joint fluid T lymphocytes in patients with juvenile rheumatoid arthritis.

Synovial fluid (SF) lymphocytes from 4 patients with pauciarticular juvenile rheumatoid arthritis (JRA) and 4 patients with polyarticular JRA were examined for their phenotypic and functional characteristics. In all 8 patients there was a high proportion of activated SF T cells, together with an increased proportion of CD2+CD3- and the presence of CD3+CD4-CD8-WT31- lymphocytes. The functional analysis at the clonal level in 5 patients (427 clones) showed a relevant proportion of cytotoxic T cell clones, which were not confined to typically cytolytic phenotypes, but were also present among CD3+CD4+CD8- cultures. Compared to those with pauciarticular JRA, patients with polyarticular disease had a significantly higher proportion of T cell clones with cytotoxic activity. Although derived from a limited number of patients, our data suggest a direct involvement of T cells in the pathogenetic mechanisms that originate and maintain the articular damage, and the possibility of different or more pronounced T cell reactivities in the clinically more diffuse JRA types.

Adolescent↗
PubMed1989

Dual-parameter flow cytometric analysis of an early lymphocyte activation antigen (CK226) and DNA content.

This study provides a direct correlation, via dual-parameter flow cytometric analysis (simultaneous assessment of surface immunofluorescence and DNA content), between activated T-cell entry into the S/G2/M phases of the cell cycle and the kinetics of expression of a novel T-cell activation antigen, termed CK226. This molecule was identified by the specific monoclonal antibody on the leukaemic T-cell line CEM/K, and it was expressed by 8-30% of resting peripheral blood lymphocytes and the majority of monocytes and granulocytes. A large fraction of activated lymphocytes acquired the CK226 antigen before DNA synthesis. Moreover, this molecule was expressed on virtually all G0/G1 and S/G2/M phase cells by day 2 after phytohaemagglutinin (PHA) activation and at day 6 after stimulation in a mixed lymphocyte culture. The time course of expression of other known activation antigens, such as Tac and transferrin receptor, was comparable to that of CK226. Based on the relationships between CK226 expression on cycling cells and the stimulatory effects of the specific monoclonal antibody, we conclude that CK226 should be considered an early activation antigen, which defines a new pathway of T-cell activation.

Antibodies, Monoclonal↗
PubMed1989

CK226: a novel surface molecule involved in human T cell activation.

In this report we describe a novel surface molecule, termed CK226, which mediates activation of human T lymphocytes. This molecule was identified by the monoclonal antibody (mAb) CK226 that had been raised against the human leukemic T cell line CEM/K. The CK226 mAb reacted with 10%-35% of human peripheral blood lymphocytes, virtually all monocytes, polymorphonuclear leukocytes and large granular lymphocytes. As demonstrated by two-color cytofluorimetric analysis, the majority of CK226+ lymphocytes were CD3+, whereas a minority coexpressed surface immunoglobulins. Biochemical analysis showed that the surface molecules immunoprecipitated by CK226 mAb from lysates of 125I surface-labeled cloned T lymphocytes were represented by two distinct polypeptides. Their apparent molecular mass was 160 kDa and 80 kDa under nonreducing conditions and 75 kDa and 80 kDa under reducing conditions. CK226 mAb induced proliferation of peripheral blood lymphocytes and interleukin 2 release. Cell proliferation was optimal in the presence of submitogenic doses of phorbol 12-myristate 13-acetate. Finally all T cell clones analyzed for their responsiveness to CK226 mAb released interleukin 2 in the presence of the antibody, regardless of their CD4+ or CD8+ phenotype. Antibody-induced modulation of CD3/T cell receptor molecules inhibited further responses of cloned cells to CK226 mAb. Thus, we conclude that CK226 mAb defines a novel surface molecule which initiates an alternative pathway of T cell activation in humans.

Animals↗
PubMed1989

Identification of a new surface molecule expressed by human LGL and LAK cells production of a specific monoclonal antibody and comparison with other NK/LAK markers.

Recently we described a new monoclonal antibody, termed LAK1, which recognizes a 120-kDa surface antigen that is expressed on virtually all LGL and LAK precursors and effectors. In the present study we describe a second mAb, termed LAK2, which was derived against cloned LAK cells. The LAK2 mAb, similar to the LAK1 mAb reacts with a subset of peripheral blood lymphocytes which includes the precursors of LAK cells. In addition, among IL2-activated peripheral lymphocytes, this antibody defines cells displaying LAK activity. The expression of the LAK2 molecule on PBMC was analyzed by two-color cytofluorometric analysis in comparison with the expression of both T cell and LGL markers. We show that most resting LAK2+ cells lack surface expression of CD3, whereas nearly 60% express CD2 antigen. Moreover, all CD16+ and CD56 (NKH1)+ lymphocytes coexpressed both LAK2 and LAK1 antigens. Morphological analysis of LAK2+ lymphocytes indicated that the majority of these cells was represented by LGL. Thus the expression of the LAK2 molecule on LGL-enriched populations was compared by two-color cytofluorometric analysis to that of other known LGL markers such as CD16, CD57 (HNK1), and LAK1. Most LGL coexpressed LAK1, LAK2, CD16 and CD57 antigens Finally, the surface molecule recognized by LAK2 mAb is composed of two chains with apparent molecular masses of approximately 110 and 140 kDa.

Animals↗
PubMed1989

Increased plasma levels of platelet-derived growth factor activity in patients with progressive systemic sclerosis.

We measured mitogenic activity of whole blood serum and platelet-poor plasma-derived serum of a group of 10 patients with progressive systemic sclerosis and of 8 controls. Mitogenic activity of plasma-derived serum was greater in patients than in controls, in the absence of other signs of platelet activation. This increased activity was inhibited by specific antibodies, anti-platelet derived growth factor, suggesting that circulating levels of platelet-derived growth factor may be present in progressive systemic sclerosis patients. Platelet-derived growth factor, released either by platelets or by monocytes, might play a role in the pathogenesis of scleroderma.

Biological Assay↗
PubMed1989

The blood platelet as an inflammatory cell.

Platelets seem to be involved in inflammatory responses. They release substances which can cause vasodilation or vasoconstriction. Platelet Derived Growth Factor (PDGF) induces monocyte accumulation and activation and there is evidence that some mediators released from these cells can affect neutrophil migration as well as function. Furthermore, platelet derived cytokines participate in the processes of tissue repair, particularly fibroblast proliferation and matrix remodelling. We review some of the possible mechanisms which have been proposed to explain this role of platelets in the appearance and persistence of inflammatory reactions at the tissue sites.

Blood Platelets↗
PubMed1988

Human cytolytic cell clones lacking surface expression of T cell receptor alpha/beta or gamma/delta. Evidence that surface structures other than CD3 or CD2 molecules are required for signal transduction.

We have analyzed the transmembrane signaling operating in human cytolytic lymphocytes lacking surface expression of the CD3/TCR complex. Peripheral blood lymphocytes were fractionated into CD3+ and CD3- on the FACS and cloned under limiting conditions in the presence of PHA and IL-2. Approximately 90% CD3+ and 10% CD3- cells underwent clonal expansion. Clones obtained from the CD3- fraction belonged to two main phenotypic groups: CD2+ CD7+ and CD2- CD7+. Several clones were expanded and analyzed for surface phenotype and function. All of the five clones selected for detailed analysis did not express CD4, CD8, and CD28 antigens and did not release IL-2, whereas they displayed cytolytic activity against NK-sensitive, NK-resistant, and fresh tumor target cells. After stimulation with anti-CD2 mAbs or PHA a rapid increase in [Ca2+]i was detected in CD3- CD2+ CD7+ clones. This increment was caused by the release of Ca2+ from intracellular stores and by the influx from the extracellular compartment. Signaling in response to PHA did not appear to be dependent upon surface expression of CD2 molecules since antibody-induced modulation of CD2 did not prevent PHA-induced signal transduction. Similarly, in CD3- CD2- CD7+ clones [Ca2+]i increments and inositol phosphate formation occurred after stimulation with PHA. These data indicate that the functional PHA-binding structures, expressed in both groups of CD3- clones, are distinct from CD3/TCR complex and CD2 molecules.

Antibodies, Monoclonal↗
PubMed1988

Effects of long-lasting antiepileptic therapy on brainstem auditory evoked potentials.

The brainstem auditory evoked potentials of 84 epileptic patients in chronic monotherapy with carbamazepine (n = 36), phenobarbital (n = 19), Na-valproate (n = 20) or progabide (n = 9) were studied. The mean values of I-III and I-V interpeak latencies (IPLs) were respectively 2.16 +/- 0.11 and 4.03 +/- 0.17 in the control group, 2.31 +/- 0.09 and 4.17 +/- 0.16 in the valproic group, 2.30 +/- 0.17 and 4.19 +/- 0.20 in the carbamazepine group, 2.17 +/- 0.16 and 4.10 +/- 0.18 in the phenobarbital group and 2.16 +/- 0.11 and 4.12 +/- 0.17 in the progabide group. The prolongation of I-III and I-V IPLs was statistically significant only for the valproic acid and carbamazepine groups. Neither duration of the epilepsy and treatment and frequency of seizures nor the serum drug levels were correlated with I-V IPL values.

Adolescent↗
PubMed1988

Platelet contribution to cancer cell growth and migration: the role of platelet growth factors.

Blood platelets contain several growth factors and inhibitors. The better known among them are named platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF beta), active as modulators of growth of normal mesenchymal and epithelial cells. Cancer cell growth in vitro seems to be independent of the effects of exogenous peptides, but dependent on the cell ability to release autocrine growth factors, similar to PDGF or TGF beta. In addition, platelet-associated growth factors and inhibitors, which are able to induce a fibrotic response in connective tissue cells, might also play a role to modulate the desmoplastic reaction surrounding the tumor.

Blood Platelets↗
PubMed1987

Antibody-induced modulation of the CD3/T cell receptor complex causes T cell refractoriness by inhibiting the early metabolic steps involved in T cell activation.

We investigated the mechanism involved in T cell unresponsiveness that follows the monoclonal antibody-induced surface modulation of the CD3-TCR complex. We determined whether modulation of CD3-TCR affected the early metabolic steps such as [Ca2+]i rise and InsP3 formation. A strong inhibition of the increase on [Ca2+]i mediated by either anti-TCR or anti-CD2 mAbs was detected. In contrast, surface modulation of CD2 molecules did not prevent the [Ca2+]i increase induced by anti-TCR mAb. Similarly, InsP3 increase was strongly reduced only after modulation of CD3-TCR complex (but not of CD2 molecules). Therefore, it appears that surface modulation of CD3-TCR complex causes T cell refractoriness by inhibiting the very early metabolic events that follow receptor-ligand interactions.

Antibodies, Monoclonal↗
PubMed1987

Characterization of CD3+, CD4-, CD8- clones expressing the putative T cell receptor gamma gene product. Analysis of the activation pathways leading to interleukin 2 production and triggering of the lytic machinery.

Four clones were derived from human peripheral blood T lymphocytes from which CD4+ and CD8+ cells had been removed by treatment with specific mAbs and complement. All expressed the CD2+, 3+, 4-, 8-, T44- phenotype, and did not react with the WT31 mAb, which is specific for a framework determinant of the CD3-associated alpha/beta heterodimer which serves as receptor for antigen on most human T lymphocytes. Surface iodination followed by crosslinking with dithiobis-succinimidyl propionate (DSP) and immunoprecipitation with anti-CD3 mAbs indicated that, in all four clones, the CD3-associated molecules consisted of a major 45 kD band and a minor band of 43 kD. Northern blot analysis showed that mRNA for the gamma chain was expressed at high levels, whereas mRNA for the alpha chain was missing; beta chain mRNA was present in a defective form (1 kb instead of 1.3 kb). These data support the concept that these clones may express, in association with CD3, the molecular product of the T cell receptor gamma genes instead of the typical alpha/beta heterodimer. CD3+, WT31- clones lysed the NK-sensitive K562 target cells and produced IL-2 upon stimulation with PHA. In addition, they released IL-2 after triggering with soluble anti-CD3 mAbs or with an appropriate combination of anti-CD2 mAbs (in the presence of adherent cells). When CD3+, WT31- clones were incubated with an anti-CD3 producing hybridoma as triggering target, the latter was efficiently lysed. Target cell lysis also occurred when a suitable combination of anti-CD2 mAbs-producing hybridomas was used. Therefore, CD3+, WT31- cells appear to use two pathways of cell activation that function also in conventional CD3+, WT31+ T cells, but they lack a third putative pathway initiated by T44 surface molecules.

Antibodies, Monoclonal↗
PubMed1987

Transmembrane signalling via the T11-dependent pathway of human T cell activation. Evidence for the involvement of 1,2-diacylglycerol and inositol phosphates.

It has previously been shown that some anti-T11 monoclonal antibodies, when used in combination, can activate the human T cell line Jurkat to produce interleukin 2. In this study, we investigate the mechanism by which perturbation of different epitopes of T11 molecules induces activation in Jurkat cells. We show that this activation is initiated by a T11-mediated increase in the concentration of free cytoplasmic calcium ions ([Ca2+]i). The initial increment in [Ca2+]i can occur when extracellular Ca2+ is depleted by EGTA, indicating that Ca2+ from intracellular stores is mobilized. As an early response to extracellular signals provokes a rapid breakdown of a class of lipid known collectively as the phosphoinositides, we measured the levels of phosphatidylinositol bisphosphate (PIP2) which is hydrolyzed to generate inositol triphosphates (IP3), the putative mobilizer of Ca2+ from internal stores and 1,2-diacylglycerol (DAG), the physiological activator of protein kinase C. Monoclonal antibodies directed either against different epitopes of T11 molecules or the T3-Ti antigen receptor complex provoke a rapid breakdown of PIP2, the parental product from which IP3 and DAG derive. In addition antibodies to either the T11 molecules or T3-Ti antigen receptor complex induce marked elevations in IP3, other inositol phosphate compounds and DAG. Taken together, these data indicate that, during T cell activation, due to the perturbation of T11 molecules or T3-Ti antigen receptor complex, membrane phosphoinositides are specifically hydrolyzed. This hydrolysis of phosphoinositides generates two putative second messengers such as IP3 and DAG, which mobilizes Ca2+ from intracellular stores and stimulates protein phosphorylation, respectively.

Antibodies, Monoclonal↗
PubMed1987

CD3+ WT31- peripheral T lymphocytes lack T44 (CD28), a surface molecule involved in activation of T cells bearing the alpha/beta heterodimer.

We have applied two-color fluorescence cytofluorometric techniques to the analysis of the distribution of T44 and CD3 antigens in peripheral blood human lymphocytes. While most CD3+ cells co-expressed T44 antigen, a small distinct subset was CD3+ T44- (2-10% of CD3+ cells). This cell subset also did not react with the WT31 monoclonal antibody (mAb), specific for an alpha/beta framework determinant of the T cell receptor (TCR). Lack of T44 antigen expression was also observed in purified CD3+ WT31- polyclonal populations that had been cultured in medium containing interleukin 2 (IL2) and as well as greater than 30 clones expressing the CD3+4-8-WT31- surface phenotype. Immunoprecipitation experiments confirmed that expression of T44 molecules was confined to CD3+ WT31+ peripheral blood T cells. While conventional CD3+ WT31+ cells produced IL2 in response to mAb directed to CD2, CD3 or T44 surface molecules, CD3+ WT31- cells did not respond to anti-T44 mAb but released IL2 following stimulation with anti-CD2 or anti-CD3 mAb. Therefore, assuming that anti-T44 mimicks the effect of a still undefined natural ligand our data suggest that T cells expressing the gamma-gene surface product may be signalled by stimuli which differ, at least in part, from those acting on CD3+ WT31+ T lymphocytes.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Selection and characterization of T-cell variants lacking molecules involved in T-cell activation (T3 T-cell receptor, T44, and T11): analysis of the functional relationship among different pathways of activation.

A clone of the interleukin 2-producing Jurkat leukemia cell line termed JA3 (surface phenotype, T3+, Ti+, T44+, T11+, T40+) has been used to induce and select cell variants lacking surface molecules involved in T-cell activation. Following 200 rad of gamma-radiation (1 rad = 0.01 Gy), cells were treated with monoclonal antibodies (mAbs) directed to T3, Ti, T44, or T11 antigen and complement. After growth of the residual cells in culture, "negative" cells were cloned under limiting conditions. Depending on the specificity of the mAb used for the immunoselection, three groups of variants were obtained. (i) The use of mAbs directed to T3 or Ti resulted in cell variants that expressed the T3 Ti- T44+ Leu1+ T11+ T40+ 4F2+ HLA class I+ surface phenotype. (ii) Immunoselection with anti-T44 mAb resulted in 2 variants that shared the T3- Ti- T44- Leu1- T11+ T40+ 4F2+ HLA class I+ phenotype. (iii) Cell treatment with anti-T11 mAb resulted in 15 variants characterized by the lack of T11 antigen expression and of all the other T-cell-specific surface antigens. Therefore, it appears that the different sets of JA3 cell variants, like T cells at discrete stages of intrathymic differentiation, may follow a coordinated expression of surface differentiation antigens. Analysis of the functional responsiveness of the three distinct groups of JA3 cell variants to different stimuli showed that all produced interleukin 2 in response to A23187 calcium ionophore plus phorbol 12-myristate 13-acetate. The first group of variants (T3- Ti-) did not respond to stimulation with anti-T3, anti-Ti, or anti-T44 mAbs. Eight of 9 did not respond to phytohemagglutinin either; however, all responded to appropriate stimulatory combinations of anti-T11 mAbs (and to calcium ionophore). The second group of variants (T3-, Ti-, T44-, T11+), similar to the first group, did not respond to anti-T3, anti-Ti, anti-T44 mAbs, and phytohemagglutinin, but they were fully responsive to anti-T11 mAb. The last group of variants (lacking all the T-cell-specific surface antigens) only responded to calcium ionophore A23187.

Antibodies, Monoclonal↗
PubMed1986

Modulation of surface T11 molecules induced by monoclonal antibodies: analysis of the functional relationship between antigen-dependent and antigen-independent pathways of human T cell activation.

Previous data indicated that T lymphocyte activation can be achieved by using a combination of anti-T11 monoclonal antibodies (mAb) directed to the "T11(2)" and the "T11(3)" epitopes, respectively. Unlike the T cell activation induced by antibodies directed to the T3-T cell receptor (Ti) complex or to T44 molecules, the anti-T11 mAb-induced cell activation was not accompanied by surface modulation of the T11 antigen. In the present study we show that appropriate stimulatory combinations of anti-T11 mAb are able to induce T11 antigen modulation in a variety of T cells including polyclonal peripheral blood populations, normal as well as leukemic (JA3) T cell clones. The first anti-T11 mAb combination leading to both cell activation and T11 antigen modulation was given by a mAb directed to the T11(2) epitope and by another mAb recognizing an epitope belonging to the T11(1) group. The second combination was given by two mAb directed against two different determinants of the T11(1) group. The ability to induce T11 antigen modulation allowed a more precise analysis of the pathway of T cell activation initiated by T11 molecules and its physical and functional relationship with the other known pathways of T cell activation. T cells following T11 antigen modulation failed to respond to subsequent stimulation with anti-T11 mAb. The refractory period lasted for 48-72 h and the restoration of the responsiveness to anti-T11 mAb coincided with the re-expression of T11 molecules at the cell surface. Modulation of T11 antigen did not affect the surface expression of T3, Ti or T44 molecules, in addition, "modulated" cells maintained their ability to respond to mAb directed against T3, Ti or T44 molecules. On the contrary, antibody-induced modulation of the T3-Ti receptor complex abrogated both T11- and T44-dependent T cell activation. Finally, antibody-induced modulation of T44 antigen did not inhibit either the T11- or the T3-Ti-dependent pathway of T cell activation. These data indicate that down-regulation of the pathway of T cell activation initiated by T11 molecules can be induced not only by modulation of the antigen receptor complex but also by appropriate mAb to T11 molecules and, presumably, by the natural ligand binding to T11 molecules.

Antibodies, Monoclonal↗
PubMed1986

Signal transducing mechanisms involved in human T cell activation via surface T44 molecules. Comparison with signals transduced via the T cell receptor complex.

Antibodies against the T44 surface molecule have been shown to activate human T cells to produce interleukin 2. The role of Ca2+ in the triggering of the interleukin 2-producing Jurkat T cell line by anti-T44 monoclonal antibody has been investigated. We show that activation is initiated by an increase in the concentration of free cytoplasmic calcium ions [Ca2+]i. Subsequently, we have investigated the mechanism by which perturbation of T44 molecules induces increases of [Ca2+]i in Jurkat cells. We show that the anti-T44-mediated increase in [Ca2+]i can occur only in presence of extracellular Ca2+, since no increment is detectable when extracellular Ca2+ is depleted by EGTA. Thus, it appears that perturbation of T44 molecules, unlike that of T3-Ti antigen receptor complex, fails to mobilize Ca2+ from intracellular stores. As inositol triphosphate is considered the putative mobilizer of Ca2+ from internal stores, we measured the levels of inositol triphosphate and of the other inositol phosphate compounds in Jurkat cells after stimulation with anti-T44 antibodies. In contrast to the stimulation via the T3-Ti antigen receptor complex, stimulation via T44 molecule does not induce increments of all three inositol phosphates. Taken together, these data indicate that stimulation mediated by the T44 molecule proceeds via a mechanism independent from the typical inositol lipid metabolism which does not involve mobilization of Ca2+ from internal stores.

Antibodies, Monoclonal↗