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Biomedical subjects

L M Larocca

Publications and source records attributed to L M Larocca.

At least 91 records · Page 5Linked to original sources
PubMed1990

Type II oestrogen binding sites in acute lymphoid and myeloid leukaemias: growth inhibitory effect of oestrogen and flavonoids.

The presence of oestrogen receptors (ER) and type II oestrogen binding sites (type II EBS) have been investigated by a whole cell assay in seven cases of acute lymphoid leukaemia (ALL) and 16 cases of acute myeloid leukaemia (AML). ER were detected in 6/7 ALL patients with values ranging between 133 and 2268 sites/cell and in 12/16 AML patients with values ranging between 274 and 4197 sites/cell. The apparent dissociation constant (KD) for ER was 0.6 +/- 0.3 nM (mean + SD of 20 cases). All blasts from ALL and AML patients expressed type II EBS at variable levels ranging between 3109 and 239450 sites/cell. The mean KD value for these sites was 18.3 +/- 5.6 nM (mean +/- SD of 23 cases). Specificity experiments demonstrated that type II EBS are oestrogen specific relative to the class of steroid hormones. In addition, the flavonol quercetin was able to compete for [3H]17 beta-oestradiol (E2) binding to type II EBS, the relative binding affinity (RBA) of quercetin being greater than that of diethylstillboestrol (DES). DES and quercetin exerted a dose-dependent inhibition of ALL and AML blast proliferation in the range of concentrations between 10(-8) and 10(-5) M. The RBA of DES and quercetin for type II EBS correlated well with their potency as cell growth inhibitors. Moreover, the flavonols rutin and hesperidin which compete slightly for [3H]E2 binding to type II EBS, were scarcely effective in inhibiting leukaemic cell proliferation. The inhibitory effect of DES and quercetin was not due to a non-specific cytotoxic action since after a 1 d culture period, cell viability did not vary between control and treated cells, being greater than 80%. Our results suggest that high oestrogen concentrations and the flavonol quercetin may inhibit leukaemic blast proliferation through a common mechanism involving a binding interaction with type II EBS.

Adolescent↗
PubMed1990

Cells immunoreactive for neuropeptide in human thymomas.

The presence of opioid peptides, bombesin, and substance P was investigated by immunohistochemistry in tissue sections from six human thymomas. The number of immunoreactive cells seemed to vary from one case to another. Ultrastructural investigation, showing the presence of desmosomes in labelled cells, allowed these cells to be classified as epithelial lineage cells. The occurrence of cells containing neuropeptide in thymomas suggest that peptide molecules could have modulated the behaviour of this tumour, given the reported influence of these molecules on immune functions and their growth promoting activity on several cell types, including mesenchymal and epithelial cells.

Aged↗
PubMed1990

Type II oestrogen binding sites in human colorectal carcinoma.

Seven cases of colorectal adenocarcinomas were investigated for the presence of oestrogen receptors and progesterone receptors. The tumours specifically bound oestradiol. This binding almost exclusively resulted from the presence of high numbers of type II oestrogen binding sites. Oestrogen receptors were absent or present at very low concentrations. Immunohistochemical investigation of nuclear oestrogen receptors gave negative results. This indicates that antioestrogen receptor antibodies recognise oestrogen receptors but not type II oestrogen binding sites. The presence of specific type II oestrogen binding sites and progesterone binding offers further evidence for a potential role for these steroids and their receptors in colorectal carcinoma.

Adenocarcinoma↗
PubMed1990

Interleukin-2 receptor expression in human mast cells and basophils.

Surgical human thymus, upper respiratory tract, lung and small and large bowel specimens were analyzed for the presence of interleukin 2 receptor (IL2-R)-positive cells. Histochemical (toluidine) and immunologic (anti-IL2-R monoclonal antibody) staining procedures revealed a distinct anti-IL2-R positivity in most of metachromatically staining cells. These positive cells were observed not only in tissues showing strong inflammatory reaction and mast cell hyperplasia, as in Crohn's disease, but also in those not histologically affected by pathologic conditions. This finding suggested that human mast cells, like T blast cells, express the p55 chain of IL2-R on their surface. To see whether IL2-R was being actively synthesized, a cell preparation rich in peripheral blood basophils (PBB), which are cells closely related to mast cells, was obtained. Ultrastructural analysis of PBB after indirect immunogold procedure revealed that the vast majority expressed the IL2-R. Moreover, the presence of intracellular reaction products in the cytoplasm of most membrane-positive PBB was indicative of active antigen synthesis. Furthermore, Northern blot analysis evidenced specific IL2-R mRNA in PBB, while its expression was augmented several times when PBB were cultured in the presence of stimulated T cell supernatant.

Animals↗
PubMed1989

Chronic myeloid leukemia with monoclonal gammopathy terminating in myeloid crisis and immunoblastic lymphoma.

A patient, with chronic myeloid leukemia and IgA monoclonal gammopathy, who contemporaneously developed myeloid blast crisis and immunoblastic lymphoma is reported. Cytogenetic studies showed complex chromosome abnormalities concerning chromosomes 8, 14 and 22, other than the Ph chromosome. A possible relationship between the emergence of immunoblasts from slow proliferating lymphoplasmacytoid cells, myeloid blasts crisis and chromosomal changes is discussed.

Blast Crisis↗
PubMed1989

Immunopathology of nasal polyps: an immunohistochemical approach.

We studied the mast cells and the T-lymphocyte subpopulations of four patients' nasal polyps using immunohistochemical procedures. The data showed that MC displayed IL2-receptor and that they were very often closely related to CD4+ and MHC class II-positive T-lymphocytes. CD8-positive T-cells represented only 10% to 15% of the whole lymphoid population and were not localized near mast cells. These findings suggest a possible role of cell-mediated immune reactions in the pathogenesis of nasal polyps.

Adult↗
PubMed1989

The expression of functional IL-2 receptor on activated macrophages depends on the stimulus applied.

Human peripheral blood monocytes (Mo) synthesize prostaglandin E2 (PGE2) when activated with lipopolysaccharide (LPS). This production is strongly enhanced by the addition of supernatant from phytohaemagglutinin (PHA)-activated T cells. To evaluate the factor(s) responsible for this enhancement we studied the effect of several cytokines on the PGE2 metabolism. Recombinant interleukin-1 (IL-1) or recombinant IL-2 strongly enhanced PGE2 synthesis in LPS-stimulated Mo cultures, whereas recombinant interferon-gamma (IFN-gamma) partially inhibited its production. To see whether the effect of IL-2 on Mo was due to the presence of IL-2 receptor (IL-2R) on the cell surface, flow cytometric analysis and electron microscopy were used to investigate IL-2R expression in unstimulated and stimulated Mo. Stimulated, but not resting, Mo displayed the p55 IL-2R chain on their cellular surface and associated with the polyribosomes of the rough endoplasmic reticulum in the cytoplasm. This finding strongly suggested that the p55 chain of the IL-2R was synthesized by activated Mo. To confirm this result, 125I-labelled IL-2 was bound under high- and low-affinity conditions and cross-linked to Mo cultured in the presence of LPS, IFN-gamma or IL-1. The cross-linked 125I-IL-2/IL-2R complexes were analysed by SDS-PAGE. Mo cultured with LPS, IFN-gamma and IL-1 expressed the p55 protein detected by low-affinity cross-linking, whereas only LPS-stimulated Mo displayed a barely detectable band with an apparent MW of 70,000 under high-affinity binding conditions. In addition, stimulated Mo were found capable of producing the soluble form of IL-2R. Finally, LPS-activated Mo only responded to the addition of IL-2 by an increase in PGE2 production, suggesting that the function of IL-2R on activated Mo is linked to the stimulus applied.

Biological Factors↗
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

OKT4/OKT8 ratio and serum beta 2-microglobulin in mycosis fungoides and chronic benign dermatitis.

Pre-treatment Serum Beta 2-microglobulin (S B2-m) and OKT4/OKT8 Ratio (T4/T8 R) were studied in 15 patients with Mycosis Fungoides (MF) and in 10 subjects with Chronic Superficial Benign Dermatitis (CSBD) in order to verify whether these parameters may lend support to an earlier differential diagnosis. S B2-m levels and T4/T8 R showed no significant difference in CSBD as compared to normal controls. MF patients displayed elevated S B2-m and T4/T8 R values in comparison to healthy controls and subjects suffering from CSBD (P less than 0.001). After photochemotherapy (PUVA), markedly decreased S B2-m and T4/T8 R values were observed in all patients but two who proved to be unresponsive to PUVA treatment. On the basis of reported data, S B2-m and T4/T8 R can be regarded as an additional tool to discriminate CSBD and MF when clinical and histological features are not significantly diagnostic. Finally, these parameters seem to provide reliable information in monitoring response to treatment.

Adult↗
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↗