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N Maggiano

Publications and source records attributed to N Maggiano.

At least 91 records · Page 5Linked to original sources
PubMed1988

Alterations in thymocyte subpopulations in Down's syndrome (trisomy 21).

To correlate the histologically observed thymic abnormalities with the cellular immunodeficiency found in Down's syndrome (DS), thymus fragments and thymocyte suspensions from 14 noninstitutionalized DS subjects were studied. Histologic examination and immunohistologic studies using an anticluster of differentiation (CD) 1 monoclonal antibody showed a contracted cortex due to cortical thymocyte depletion. When DS unselected thymocytes were phenotyped, a significant reduction of CD3-, CD1-, CD4-, and CD8-positive cells was found as compared to controls. To evaluate if the deficient expression of these markers was due to the reduction of thymocyte subsets identifiable on the basis of their physical properties, we separated DS unselected thymocytes into 10 fractions by continuous Percoll density gradient centrifugation. DS thymuses were almost completely devoid of high density thymocytes. Since in normal thymus, these cells correspond to small CD1+, CD4+, CD8+, and 50% CD3+ cortical thymocytes, their absence may explain the unrestricted reduction of markers on DS unfractionated thymocytes. Furthermore DS thymuses appeared to be enriched in CD1+ first fraction (Fr1) low density thymocytes of the Percoll gradient. Fr1 CD1+ cells constitute the main spontaneously proliferating pool in normal human thymus. When the spontaneous proliferating activity of DS Fr1 was compared to that of the control, a significant reduction was observed. This reduction associated with the absence of high density thymocytes, with the reduction of cells expressing alpha- and beta-chains of the T cell receptor and in conclusion with the lymphocyte depletion, suggests that in DS thymuses there is a deficient expansion of immature T cells resulting in a reduction of the various thymocyte subpopulations, including the thymocyte pool able to differentiate into functionally mature T cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Expression of T cell receptor-alpha and -beta subunits in human thymocytes. An immunocytologic study.

The expression of the T cell receptor (Ti)-alpha and -beta subunits in human thymocytes was studied with the use of two rabbit antisera directed at constant regions of human Ti-alpha- and Ti-beta-chains (H36 and H38, respectively). Immunoperoxidase techniques were employed to count by light and electron microscopy the cells, in the various thymocyte subsets, bearing Ti-alpha and Ti-beta subunits. Of the unfractionated thymocytes, 88% +/- 5 SD and 56% +/- 8 SD were labeled by H38 and H36, respectively. More than 90% of cells in cluster of differentiation (CD)-1+ (mainly cortical) and CD1-CD3+ (mainly medullary) subsets were stained with H38. When tested by H36, 51% +/- 6 SD of CD1+ and 81% +/- 8 SD of CD1-CD3+ thymocytes were positive. In the immature CD3-CD1- subpopulation, less than 3% of cells reacted with H36, whereas 15% +/- 3 SD were stained by H38. Flow cytometry revealed that CD1+ (mainly cortical) thymocytes expressed CD3 surface antigen in a percentage similar to that of CD1+ cells positive for Ti-alpha subunits. Indirect double labeling procedures with immunogold- and peroxidase-conjugated second antibodies demonstrated that almost all CD1+/Ti-alpha + cells expressed the surface CD3 antigen, whereas a large proportion of CD1+/Ti-beta + cells did not. These results indicate a sequential expression of Ti-beta and Ti-alpha subunits during intrathymic T cell differentiation. They also suggest that assembly and surface expression of the CD3-Ti complex are linked to the production of Ti-alpha-chains in addition to Ti-beta subunits. Last, the expression of Ti-alpha and Ti-beta subunits was studied in peanut agglutinin (PNA)+, CD1+ blasts representing the main, spontaneously proliferating intrathymic pool. The lack of Ti-alpha and Ti-beta subunits and the absence of surface CD3 antigen on most of these blasts suggest that immature T cells are compelled to proliferate in the thymus in a CD3-Ti complex independent manner.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

T cell surface markers expression by immature human thymocytes in in vitro culture: role of Ia+ accessory cells.

Previous studies have indicated that the human thymus is composed of several discrete compartments. Cortical thymocytes are reactive with the monoclonal antibody anti-T6, whereas most medullary cells, unreactive with anti-T6, stain brightly with anti-T3 antibody, which defines mature T cell populations. By using an indirect immune rosette method, we isolated the minor thymocyte population (1 to 2% of all thymocytes) lacking both T3 and T6 but expressing T11 antigens. These cells could be maintained in culture supplemented with recombinant IL 2 (Rec-IL 2) for several days. Under these conditions, T3-T6- cells were shown to undergo phenotypic changes. In the absence of thymic macrophage (Mo), T3+ and T8+ thymocytes appeared in culture, whereas the development of T4+ cells strictly required the presence of Mo. The expression of T4 antigen could be largely prevented by the addition of anti-HLA-DR antibody, further indicating that Ia+ accessory cells had the ability to promote in vitro development of T4+ thymocytes. In the presence of Mo, not only T4+ but also T8+ cells were obtained. Double fluorescence staining with anti-T8-FITC and anti-T4-biotin demonstrated that after 12 days of culture, T4 and T8 antigens were mutually exclusive. Furthermore, during the course of these studies, we observed that under the culture conditions utilized (e.g., presence or absence of Mo), T3-T6-thymocytes failed to express the T6 antigen. Thus, the in vitro development of T cells bearing a mature phenotype could be obtained in the absence of intermediate expression of cortical (T6+) thymocytes.

Animals↗
PubMed1987

Glucocorticoid receptors and corticosensitivity of human thymocytes at discrete stages of intrathymic differentiation.

Human thymus is composed of several discrete compartments. Stage III thymocytes, located mainly in the medulla, stain brightly with anti-T3 monoclonal antibody; stage II thymocytes, located in the cortex, are T3- but react with T6 antibodies. The earliest identifiable intrathymic cell (stage I) expresses the sheep erythrocyte glycoprotein T11 but not T6 or T3 antigens. Within the thymus a phenotypically heterogeneous pool of proliferating lymphoblasts is present. This capacity to proliferate without in vitro activation is mainly attributable to thymocytes unable to respond to mitogens and expressing the cortical T6 marker. Both T3+ and T3-T6- cells respond to mitogen. However, in order to exhibit maximal proliferative responses, T3+ but not T3-T6- thymocytes require the addition of exogenous IL 2. Thymocyte subsets at distinct stages of intrathymic differentiation were then analyzed for glucocorticoid (GC) receptor content by using a whole cell assay with 3H-triamcinolone acetonide as tracer. The least mature T3-T6- thymocyte subset contained the highest levels of GC receptors . T3+ thymocytes exhibited a receptor content higher than that found in T6+ cells and similar to that reported for peripheral blood lymphocytes. Apart from the number, the GC receptor sites in all thymocyte subsets were similar in their affinities, kinetic characteristics, specificity for steroids, and ability to undergo translocation from cytoplasm to nucleus, and they behave in all these respects like binding sites of GC receptors in lymphoid and other cells. Independently of both phenotype and GC receptor content, all in vivo activated thymocytes (i.e., spontaneously proliferating cells) were similarly sensitive to the steroid inhibitory action in vitro. Both in the presence and in the absence of exogenous IL 1 or IL 2, the PHA-induced mitogenesis of T3-T6- cells was less inhibited by GC than that of T3+ thymocytes. Exogenous IL 1 and IL 2 were equally effective in removing, although not completely, the GC inhibition on T3-T6- proliferative responses to PHA. Relative to T3+ cell mitogenesis, only exogenous IL 2 was able to antagonize the steroid inhibitory action. The capacity observed in vitro of GC to differentially affect the proliferative potential or the cell viability of thymocytes belonging to functionally distinct subsets suggests that these hormones could regulate the intrathymic maturative pathways. Finally, although at present the physiologic relevance of the highest expression of GC receptors in intrathymic precursor cells remains unclear, the receptor density may be considered a marker of differentiation for the T lymphoid lineage.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Proliferation of phenotypically immature human thymocytes with and without interleukin 2 receptors.

Previous studies have indicated that the human thymus is composed of several discrete compartments. Cortical thymocytes are reactive with the monoclonal antibody anti-T6, whereas most medullary cells, unreactive with anti-T6, stain brightly with anti-T3, which defines mature T cell populations. Only a minor thymocyte population lacks both T3 and T6 but expresses T11 antigens. Within the thymus, several proliferating lymphoblasts are present. In addition a distinct subset shows the capacity to proliferate in response to mitogens. By continuous Percoll density gradient centrifugation, we have obtained a cell fraction comprising the vast majority of cells able to proliferate spontaneously or after PHA stimulation. By a panning procedure performed with anti-T3 and anti-T6 antibodies, three phenotypically distinct thymocyte subsets were separated from this fraction, and their functional capabilities were tested. The spontaneous proliferating activity was found to be mainly attributable to thymocytes unable to respond to mitogen, expressing the cortical T6 marker and lacking receptors for IL 2. T3-positive cells are able to respond to mitogen. However, these thymocytes are incapable of producing the adequate amount of IL 2 required to fully saturate their intrinsic proliferative capability. Surprisingly, the phenotypically least mature intrathymic T lymphocytes (T3 and T6 negative) respond to phytomitogen, at least in part, in an interleukin-dependent manner. It is noteworthy that a large proportion of these T3- and T6-negative thymocytes express IL 2 receptors and class II MHC antigens without in vitro activation. These novel findings have potential implications in the context of current models of differentiation pathways within the human thymus.

Antibodies, Monoclonal↗
PubMed1986

Inhibitory effect of cyclosporin A on the OKT3-induced peripheral blood lymphocyte proliferation.

In this paper we studied the effect of cyclosporin A (CyA) on interleukin 1 (IL-1) and interleukin 2 (IL-2) production and on IL-2 receptor expression by human peripheral blood lymphocytes induced to proliferate following OKT3 monoclonal antibody stimulation. CyA inhibited T-cell proliferation in a dose-dependent manner and its effect was inversely correlated with the entity of the mitogenic signal. The drug reduced not only IL-2 synthesis but also IL-1 production. CyA was also found to be able to inhibit the expression of IL-2 receptors on T cells. By supplementing with IL-1 and/or IL-2 the cultures carried out in the presence of CyA, it became evident that the inhibition of IL-2 production mainly depended on the CyA-induced reduction of IL-1 synthesis. Thus the IL-2 production by "resting" T cells had to be considered as an IL-1-dependent event. In addition it was found that the presence of IL-1 constituted a crucial requirement for the induction and the positive modulation of IL-2 receptor expression. Although IL-2 could play a role in facilitating the expression of IL-2 receptors, its effectiveness to do so depended on the presence of IL-1. In conclusion, CyA is to be considered not only as a potent immunodepressive drug but also as a valuable tool for the study of T-cell activation and proliferation.

Antibodies, Monoclonal↗
PubMed1986

Phenotypical characteristics and proliferative capabilities of thymocyte subsets in human thymoma.

The phenotypical and functional characteristics of the lymphoid component present in ten human thymomas have been analyzed. Thymomas were classified according to the predominant epithelial cell type present in the neoplastic gland. In thymomas of the cortical type a large proportion, clearly higher than that present in mixed thymomas, of T6-positive lymphocytes was present. This T6 subset did not proliferate to mitogen but contained almost all thymocytes able to spontaneously proliferate. Higher proportions of T3-positive cells were found in mixed types of thymomas than in cortical-type tumors. This T3+ subset responded to mitogen stimulation and constituted the more mature intrathymic pool. Surprisingly we identified in thymomas a further subset, lacking the cortical and medullary markers T6 and T3, capable of responding to mitogen. The occurrence of higher proliferative responses to phytohemagglutinin (PHA) in the unfractionated population of cells from mixed thymomas than in the cells of cortical thymomas was judged to be attributable to the relatively higher content of both T3-positive and T3, T6-negative thymocytes in the former. Unlike T6+ thymocytes, T3-T6- as well as T3+ cells were practically devoid of spontaneous proliferative capacity. The expansion of the intrathymic lymphoid component in human thymomas should then be considered to be attributable to the "spontaneous" proliferative capacity of the T6+ cell pool. In this respect, cortical thymomas not only contained more T6+ cells than the mixed type but also exhibited a higher lymphocyte/epithelial cell ratio and more frequent mitotic figures.

Cell Separation↗
PubMed1986

Glial-like cells in sympathetic neural crest derivatives during human embryogenesis. Detection by S-100 immunohistochemistry.

The present study investigates at the light and electron microscopic levels the possible presence and distribution during human development of glial-like satellite cells in sympathetic neural crest derivatives by S-100 immunohistochemistry. From the earliest stages investigated, immunostained cells were detected inside sympathetic migrating masses and at their periphery, where they constituted a continuous layer isolating sympathetic elements from mesenchymal cells. The detection and peculiar distribution of these glial-like cells in developing sympathetic tissue could open new perspectives in the study of events linked to the migration and differentiation of some neural crest derivatives.

Cell Differentiation↗
PubMed1986

The mature, mitogen-responsive, human thymocyte population comprises two functionally distinct T-cell subsets differing in exogenous interleukin requirements for mitogenesis and in sensitivity to glucocorticoids.

Human thymocytes were separated into 10 fractions by continuous Percoll density gradient centrifugation. Almost all the cells able to proliferate in response to phytohaemagglutinin (PHA) and about 80% of the thymocytes carrying the mature T3 marker were contained within the first two lightest fractions (Fr1 and Fr2). However, cells in Fr1 and in Fr2 were clearly different in terms of their interleukin requirement for mitogenesis, i.e. in the presence of interleukin-1 (IL-1), Fr1 thymocytes showed proliferative responses to PHA that were three to five times greater than those of the Fr2 cells, whereas in the presence of exogenous IL-2 both Fr1 and Fr2 cells had mitogenic responses of a similar magnitude. These differences could not be explained by accessory cell contamination or by different kinetics of the proliferative responses. Furthermore, in the presence of exogenous IL-1, Fr1 thymocytes showed a greater capacity for producing IL-2. In contrast, there was no difference in the expression of functional IL-2 receptors between the two fractions. It can be concluded that the mature thymocyte subpopulation contains at least two functionally distinct subsets, which differ in density, and that during intrathymic maturation the capacities to produce and to respond to IL-2 do not develop simultaneously. Although both the number and the binding characteristics of glucocorticoid (GC) receptor sites did not differ significantly between Fr1 and Fr2 thymocytes, dexamethasone was more effective in inhibiting the PHA-induced mitogenesis of Fr2 than of Fr1 cells. Thus, the GC sensitivity of T-cell mitogenesis is not directly correlated with receptor-related variables. In contrast with observations made on peripheral T cells, the inhibitory activity of GC on thymocyte mitogenesis was only partially reversed by the addition of exogenous IL-2. Thus, the inhibitory action of GC on thymocyte mitogenesis cannot be explained only by the steroid-induced inhibition of IL-1--IL-2 production; it must also be due to a GC-inhibitory effect on the IL-2-responsive cell proliferation.

Antigen-Presenting Cells↗
PubMed1986

Estrogen binding sites in peripheral blood mononuclear cells and thymocytes from 2 myasthenia gravis patients.

In the present investigation the estrogen binding capacity of peripheral blood mononuclear cells (PBMC) and thymocytes from 2 young female Myasthenia Gravis (MG) patients has been studied. We found high levels of estrogen binding sites in both pre-thymectomy PBMC and lymphoid cells from the hyperplastic thymuses of the MG patients. A sucrose density gradient analysis revealed that the estrogen was binding to macromolecular species similar to those characterized in cytosols from classical estrogen target organs. A post-thymectomy time-dependent decrease of the estrogen binding capacity was also observed in PBMC, reaching levels similar to that of sex- and age-matched controls.

Adolescent↗
PubMed1985

Transient deficiency of peripheral blood accessory cells in supporting T cell mitogenesis in patients suffering from chronic idiopathic thrombocytopenic purpura after intravenous gammaglobulin treatment.

Mitogenic response of blood lymphocytes to phytohemagglutinin (PHA) and to OKT3 monoclonal antibodies was investigated in 7 patients suffering from chronic idiopathic thrombocytopenic purpura (ITP) before, during and after high-dose intravenous (i.v.) immunogammaglobulin (IgG) infusion. The platelet count rose above the pre-treatment values during infusion therapy in all patients but one. Five out of seven patients presented elevated platelet-associated IgG (PA-IgG) levels at the time of the first infusion; four of these showed an increase in platelet count and a transient reduction or normalization of PA-IgG after IgG infusion. Five out of seven patients showed an impairment of T lymphocyte mitogenic response to PHA and OKT3 before therapy. All patients responded to IgG therapy with a transient deficiency of FcR mediated monocytes (Mo) in supporting T cell mitogenesis induced by both mitogens during and after IgG infusion. This reduced cooperative capability of Mo disappeared at various times after the end of therapy (range 3-12 days). The transient alteration of Mo function, possibly due to a modification in the surface number or in the affinity of Fc-receptors, can explain in part, the increase in platelet count during and after IgSRK infusion.

Antibodies, Monoclonal↗
PubMed1985

Satellite cells in the normal human adrenal gland and in pheochromocytomas. An immunohistochemical study.

In light of the recent finding of the S-100 antigen in satellite cells of the rat adrenal medulla, we looked for S-100-labelled cells in both the normal human adrenal medulla and in pheochromocytomas. Immunostaining enabled us to detect S-100-labelled satellite cells by both light and electron microscopy in a significant number of pheochromocytomas and, as expected, in the normal human adrenal medulla.

Adrenal Gland Neoplasms↗
PubMed1985

Proliferative capabilities of T3-positive thymocytes.

The proliferative responses to phytohemagglutinin (PHA) and to OKT3 monoclonal antibody of various human thymocyte subsets were studied. Unfractionated thymocytes are very poorly responsive cells, as assessed by both PHA and OKT3 stimulation. The mitogen responsiveness is confined to the T3-enriched (T3+) subset, the T6-positive (T6+) cells being almost completely devoid of proliferative capacity. The addition of exogenous IL-2 increases the proliferative responses to PHA and OKT3 of both unfractionated and T3+ thymocytes. This implies that the endogenous IL-2 production by thymocytes is inadequate to fully support the intrinsic proliferative capacity of these cells. Even in the presence of an optimal amount of IL-2, T3+ thymocytes exhibit proliferative responses of lower magnitude as compared to those of peripheral T counterpart (PBT). These observations indicate that the maturative level attained by the T3+ subpopulation within the thymus is considerably inferior to that of T3+ fully immunocompetent peripheral T lymphocytes. Macrophages are activated to produce IL-1 following the stimulation by OKT3-pulsed T lymphocytes. T3+ thymocytes are markedly less efficient than PBT in inducing IL-1 secretion. These data suggest that T3+ lymphocytes within the thymus are relatively immature in terms of cooperative capacities with accessory cells. In conclusion, T3+ cells constituting the more mature intrathymic pool do not reach a complete functional differentiation as compared with the T3+ peripheral counterpart.

Antibodies, Monoclonal↗
PubMed1985

Immunohistochemical distribution of S-100 antigen in the urinary system of man and rat.

The immunohistochemical distribution of S-100, a protein originally isolated from the brain, has been investigated at the light and electron microscopic levels in rat and man urinary systems. In both species the antigen essentially exhibited the same location, restricted, with different degrees of staining, to certain cells in the kidney, i.e. collecting tubules, thin limbs of Henle's loop and renal papillae.

Animals↗
PubMed1985

T lymphocyte subpopulations and lymphocytotoxic antibodies in patients with autoimmune haemolytic anaemia.

Evaluation of T lymphocyte subpopulations was performed on peripheral blood of patients affected by idiopathic or associated autoimmune haemolytic anaemia. A marked reduction of absolute number of T gamma and T mu cells was observed in 11 of 16 patients; a decrease of both OKT4+ and OKT8+ cells was found in 8 of 10 patients. Circulating cytotoxic antibodies against autologous and allogenic T lymphocytes and/or thymocytes were found in almost all the cases. T lymphocyte subsets depletion, probably connected to antibodies against T lymphocytes and their thymic precursors, could play a role in autoimmunity because of T3+/T4+ cell depletion.

Adult↗
PubMed1985

T3 expression by human thymocytes in culture.

By panning procedures employing T6 and T3 monoclonal antibody, human thymocytes were fractionated into two subpopulations depleted of T6- or T3-positive (T6+, T3+) cells. Unfractionated thymocytes and T6- and T3-depleted subpopulations were separately cultured for 48 h in RPMI 1640 medium with 10% FCS or in HB 101 serum-free medium. Determining the phenotype of unfractionated thymocytes at various time intervals, a time-dependent increase of T3+ cells was observed. An inverse relationship was found between the percentage of T3+ cells and the T6 and peanut agglutinin (PNA) reactive thymocytes. When the surface antigen expression in the T3-depleted population (greater than 95% T6+ and PNA+ cells) was analysed, a strong increase of T3+ cells and a complementary reduction of T6+ and PNA+ cells was evidenced. During that time the surface phenotype of the T6-depleted population (greater than 80% T3+ cells) showed the same trend of differentiation, as the other thymocyte preparations. These results indicate that a conspicuous fraction of human thymocytes and particularly of those characterized by a cortical phenotype (PNA+ and T6+ cells), are able to express mature T-cell antigens when cultured in vitro in the absence of the thymic microenvironment influence. However, the in vitro acquisition of a mature phenotype is not accompanied by a parallel achievement of the capacity to respond to mitogens such as PHA or T3 monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1985

Ultrastructural analysis of peripheral blood mononuclear cells in renal allograft recipients.

Renal transplanted patients receiving immunosuppressive therapy with glucocorticoids (GC) and azathioprine show in the peripheral blood numerous large mononuclear cells. The origin and the lineage of these cells was not clearly established. In the present study we investigated the surface phenotype and the ultrastructural characteristics of this subset constituted by large mononuclear cells. From peripheral blood mononuclear cells (PBL) of allograft recipients, a cell preparation exhaustively depleted of the relatively numerous monocytes was obtained. At ultrastructural examination two main cellular populations were distinguished: the predominant one (congruent to 85%) was constituted by cells with lymphoid morphology while the other (congruent to 15%) showed myeloid appearance. The large lymphoid cells, T4 or T8 positive, did not express Ia molecules on the surface and were morphologically suggestive of cells in an intermediate stage of the cell cycle between resting and activated lymphocytes. The myeloid population was constituted by promyelocytes, myelocytes and metamyelocytes. Promyelocytes and myelocytes capable of cell division are responsible for the increase of 3H-thymidine incorporation observed in transplanted patient PBL. In conclusion our data suggest that in allograft recipients the immunosuppressive therapy with GC and azathioprine may inhibit the lymphocyte blast transformation and can influence the release of immature myeloid cells responsible for the PBL increased 3H-thymidine incorporation.

Antibodies, Monoclonal↗