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Biomedical subjects

F O Ranelletti

Publications and source records attributed to F O Ranelletti.

At least 91 records · Page 5Linked to original sources
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

Fibrin glue vs. nylon in the anastomosis of rabbit fallopian tubes.

Fibrin glue was used in end-to-end tubal anastomosis on eight sexually mature female New Zealand white rabbits. The right fallopian tubes were anastomosed with 10/0 nylon and the left with fibrin glue (Tissucol). The animals were mated with males of proven fertility six weeks after surgery and killed two weeks later. The gestational sacs and corpora lutea on the right and left sides were counted separately and the nidation index calculated for each. The presence of adhesions was also evaluated. All the tubes were finally examined under a scanning electron microscope. The fibrin glue was satisfactory in terms of patency, pregnancy and morphology of the epithelium.

Animals↗
PubMed1986

Expression of 20 alpha-hydroxysteroid dehydrogenase activity in human lymphoid and non lymphoid cells.

Expression of 20-alpha-hydroxysteroid dehydrogenase (20 alpha-SDH), a putative T cell marker in the murine system, has been examined in human haematopoietic cells. Higher levels of enzymatic activity were expressed by human peripheral blood mononuclear cells (PBMC) in comparison with thymocytes. When PBMC were fractionated into T and non T cell subsets, the greatest values of 20 alpha-SDH activity were associated with the non T cell population. Cells from bone marrow exhibited lower levels of 20 alpha-SDH than PBMC and thymocytes. Both myeloid and lymphoid leukaemic cells expressed significant 20 alpha-SDH activity. In addition our data in U-937 and CM-S human cell lines indicate that cells belonging to the myelomonocytic precursor compartment constitutively expressed 20 alpha-SDH activity. Furthermore, this activity was less expressed when these cells were induced to monocyte-macrophage differentiation. In conclusion, our data in the human system indicate that 20 alpha-SDH should not be viewed as a lymphoid lineage-restricted marker enzyme.

20-Hydroxysteroid Dehydrogenases↗
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

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

Interleukin-1 production by a cloned line of human monocyte-like cells (CM-SM). Correlation with state of differentiation.

Interleukin-1 (IL-1) production by the human monocyte-like cloned cell line CM-SM has been investigated as a function of the state of cell differentiation. CM-SM cells were induced to differentiate along the monocyte-macrophage lineage by bacterial lipopolysaccharides (LPS) or by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Cell differentiation was studied by various morphological, functional, cytochemical, and immunological variables, whereas IL-1 activity in the supernatants was measured by the lectin-primed thymocyte proliferation assay. Unstimulated CM-SM cells constitutively produced small amounts of IL-1, and most of the cells appeared relatively undifferentiated. LPS induced cell differentiation, but the effect was reversible, and the cells, in general, did not acquire a capacity for phagocytosis. IL-1 levels were increased about 10-fold over the controls. TPA induced further cell differentiation to macrophage-like cells capable of phagocytosis. IL-1 activity could not be measured directly in the supernatants owing to the synergistic effect of TPA in the assay system. Unequivocal removal of the phorbol was not achieved, but the data indicated that the 'real' levels of IL-1 in the TPA-induced cultures were not significantly higher than those from LPS-induced cultures.

Cell Differentiation↗
PubMed1985

Effect of glucocorticoids on the development of suppressive activity in human lymphocyte response to a polysaccharide purified from Candida albicans.

The action of glucocorticoids on the proliferative response of human lymphocytes stimulated in vitro by MPPS has been investigated. The effect of Dex was dependent on the time of steroid addition to the cultures. Dex added at the beginning of the culture period inhibited, cell proliferation and IL 1/IL 2 synthesis, although not completely. However, a delayed addition of 24 to 48 hr resulted in an enhancing effect on cell proliferative responses that was maximal at day 4. The effect of Dex on T suppressor cell activity was then investigated. Dex added 1 day before the appearance of suppressor cells resulted in a marked decrease or disappearance of the suppressive activity. Moreover, primed T lymphocytes treated with Dex in the presence of exogenous IL 2 enhanced the proliferative responses of fresh autologous PBMC stimulated by MPPS. Taken together, our data suggest that glucocorticoids inhibit the differentiation of T suppressor cells and that IL 2 is unable to reverse this inhibitory effect.

Adult↗
PubMed1984

Ia- and IgG-Fc receptor-positive accessory cell sustains peripheral T lymphocyte but not thymocyte mitogenesis induced by OKT3 monoclonal antibody.

The proliferative responses of human peripheral blood mononuclear cells (PBL) and thymocytes to OKT3 monoclonal antibody have been investigated. The PBL response to OKT3 was maximal after 72 hr while that of thymocytes was inappreciable at all times measured. Unlike phytohemagglutinin, OKT3 was unable to elicit the mitogenesis of adherent cell-depleted T cells in spite of the presence of exogenously added Interleukin 1 and/or Interleukin 2. The addition of autologous or heterologous adherent cells restored the OKT3 mitogenic response of peripheral purified T cells but not of thymocyte cultures. The adherent cell population that was able to sustain the OKT3-elicited T-cell mitogenesis was constituted by Ia-, Fc receptor-positive cells. These data suggest that the adherent cell-T cell interaction is mediated via the Fc portion of the OKT3 molecule. Furthermore, unlike peripheral T cells, T3-positive thymocytes, which represent the more mature. PHA-responsive subset within the thymus, are unable to cooperate with accessory cells when pulsed with OKT3 monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1984

Glucocorticoid inhibitory action on the response to PHA of residual circulatory lymphocytes in renal transplant patients following immunosuppressive therapy.

The inhibitory effect of glucocorticoids on the in vitro response to phytohaemagglutinin of the residual circulating T lymphocytes in renal transplant patients during maintenance immunosuppressive therapy with glucocorticosteroids and azathioprine has been investigated. As in normal subjects, the steroid-induced inhibition of transplanted patients' lymphocyte response was inversely correlated with the mitogen concentration used. On the other hand, the response of the various lymphocyte preparations from transplanted patients appeared less inhibited by steroids than the corresponding preparations from normal subjects. The addition to the culture of the adherent cell product interleukin 1 was effective in removing to a similar extent the steroid inhibitory effect on lymphocytes from normal and transplanted subjects. Thus, the lesser inhibitory effect of glucocorticoids on transplanted patient lymphocytes could be explained by the higher percentages of monocytes present in all peripheral blood mononuclear cell preparations. These results suggest that during immunosuppressive therapy with glucocorticoids and azathioprine the residual circulating lymphocytes have a responsiveness to in vitro dexamethasone suppression similar to that of normal peripheral blood lymphocytes.

Antibodies, Monoclonal↗
PubMed1984

Adverse interaction between acetazolamide and anticholinesterase drugs at the normal and myasthenic neuromuscular junction level.

At skeletal neuromuscular junction level in vivo and in vitro experiments have revealed an adverse reversible interaction between acetazolamide and anticholinesterase drugs. Acetazolamide (500 mg, i.v.) prevented the increase in amplitude induced by edrophonium (5 mg, i.v.) on the action potentials derived by surface electrodes from the opponens pollicis muscle of patients affected by myasthenia gravis, when the median nerve was stimulated at the wrist by low frequency repetitive pulses (5/s). Similarly, acetazolamide significantly reduced the contractile force potentiation induced by neostigmine on the rat phrenic-diaphragm preparation, indirectly stimulated by means of low frequency repetitive pulses on the motor nerve. Under such experimental conditions acetazolamide did not show any significant action of its own, but it counteracted the effects of anticholinesterase drugs only when tested before them. It is hypothesized that the effect of acetazolamide on the skeletal neuromuscular junction may occur at presynaptic and/or postsynaptic sites by a mechanism only partly ascribable to the well-known carbonic anhydrase inhibitory activity of this drug.

Acetazolamide↗
PubMed1983

Modulation of glucocorticoid inhibitory action on human lymphocyte mitogenesis: dependence on mitogen concentration and T-cell maturity.

The inhibitory effect of glucocorticoids on the mitogenesis of human T cells derived from thymus and peripheral blood compartments have been investigated. The capacity of dexamethasone (Dex) (10(-7) M) of inhibiting the peripheral blood lymphocyte (PBL) mitogenesis was inversely correlated with the phytohemagglutinin (PHA) concentration used. Conversely, Dex completely (greater than 90%) inhibited the thymocyte mitogenesis, irrespective of PHA concentrations. T cells purified from PBL (M phi less than or equal to 1%) behaved as thymocytes regarding the Dex inhibitory pattern. The addition of macrophages (M phi) or interleukin 1 (IL1) was effective in removing the Dex inhibitory effect on T cells purified from PBL, but not on thymocytes. The higher corticosensitivity of thymocyte mitogenesis in comparison to PBL mitogenesis cannot be explained by differences in the relative number of M phi, but seems an intrinsic property of these less mature T cells.

Cell Survival↗
PubMed1983

Glucocorticoid receptors and cortico-sensitivity in a human clonal monocytic cell line, CM-SM.

CM-SM is a clonal line of human precursor mononuclear phagocytes inducible to macrophage differentiation in response to the tumor promoter phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Untreated CM-SM cells contain single class, high-affinity (KD = 4.0 X 10(-9) M) glucocorticoid-specific receptor sites (approximately 60,000 per cell), as measured by a whole cell assay, at 37 degrees C, using [3H]triamcinolone acetonide (TA). Exposure of CM-SM to dexamethasone (DEX) produced a progressive, dose- and time-related series of changes in CM-SM cell growth, saturation density, morphology, and functional properties, with half-maximal effects at about 10(-9) M for DEX. TA-receptor sites rapidly decreased (about 70%) after DEX treatment, without any apparent change in steroid specificity and affinity. After 5 days in culture with a saturating concentration (3.6 X 10(-8) M) of hormone, the cells reached a saturation density of about 9.0 X 10(6) viable cells/ml (about 4.0 X 10(6) viable cells/ml in the controls), while the modal volume of the resulting cell population was approximately 60%, as compared to the volume of untreated cells. DEX-treated cells appeared less differentiated than controls, as assessed by combined morphologic, antigenic, and cytoenzymatic analyses. DEX almost completely inhibited TPA activation of the following macrophage functions: adherency to the culture plate, expression of lysosomal enzymes, Fc and C3 receptors, and stimulation of phagocytosis. After removal of DEX, the cells, within a few passages, returned to a state apparently identical to the untreated controls and could be induced to macrophage differentiation in response to TPA.

Cell Differentiation↗
PubMed1983

Presence and steroid inducibility of glutamine synthetase in human leukemic cells.

Glutamine synthetase (EC 6.3.1.2; GS) is present in lymphoblasts from patients with acute lymphoblastic leukemia (ALL) as well as in normal peripheral blood lymphocytes. In 16 out of 20 ALL patients studied exposure of the cells to physiological concentrations of dexamethasone in vitro increased enzyme activity above the control levels. The increase was specific for glucocorticoid receptor ligands. A direct correlation was found between the magnitude of glucocorticoid-mediated increase of GS activity and the cellular levels of specific glucocorticoid receptors assayed in the same cell specimen. Moreover, the basal levels of the enzyme measured in cells prior to exposure to dexamethasone correlated negatively with receptor density. It is suggested that the presence of steroid-inducible GS in ALL cells may prove to be a marker for functional receptor sites.

Enzyme Induction↗
PubMed1983

Dissociation between coupled lymphocyte phenotypic and functional properties in Sézary cells.

Neoplastic lymphocytes derived from three patients suffering from Sézary syndrome were studied by immunologic and functional analysis. Populations of neoplastic T cells (greater than 90% as judged by morphologic criteria) were isolated from involved lymph nodes. Sézary cells expressed T3 and T4 but not T8 membrane antigens displaying the same phenotypic pattern of normal helper/inducer T cells. On the contrary the mitogenic response of Sézary cells to phytohemagglutinin appears lower than that exhibited by peripheral T lymphocytes. The amounts of interleukin 2 produced by Sézary cells were examined in two out of three cases: in one case it appeared similar to that produced by peripheral blood lymphocytes while in the other it was about one-half lower. Furthermore the capacity of dexamethasone at 10(-7) M in inhibiting T-cell mitogenesis was comparatively analyzed in T lymphocytes from Sézary lymph nodes, reactive lymph nodes, normal peripheral blood, and normal thymus. It was clearly apparent that the mitogenesis of Sézary cells, unlike that of peripheral blood lymphocytes and that of lymphocytes from reactive lymph nodes, was strongly inhibited by dexamethasone (greater than 70%); such inhibition was very similar to that observed for normal thymocytes. Taken together these results suggest that despite the phenotypic pattern of mature helper/inducer T cells, Sézary lymphocytes are functionally a less mature T-cell type.

Antigens, Surface↗
PubMed1983

A human thymoma with prothymocyte-like infiltration.

We have examined a human thymoma, round-oval epithelial-type cell with moderate lymphocytic infiltration, whose major lymphocytic component (67%), unlike the minor one (33%), did not form rosettes with sheep red blood cells (E rosettes). However, these cells were of T-cell nature as indicated by the positive staining for both acid phosphatase and beta-glucuronidase, two well-accepted cytochemical markers for T cells. The non-E-rosetting lymphocytes expressed T 10, but not T 3 and T 6 antigens. Moreover, they lacked both peanut agglutinin and Fc-IgG receptors. On the contrary, 71 and 19% of the E-rosetting cells were PNA- and Fc-IgM-receptor positive, respectively. Furthermore, the non-E-rosetting cells were phytohemagglutinin unresponsive. The non-E-rosetting lymphocytes were larger (greater than 7 micron) than the E-rosetting cells and showed a different nuclear chromatin pattern. These immunological, cytochemical, and morphological features strikingly resemble those exhibited by cells (prothymocytes) normally found only in fetal thymus. On the basis of these findings we hypothesize the existence in this thymoma of a prothymocyte-like infiltration.

Acid Phosphatase↗
PubMed1983

Human thymoma lymphocyte mitogenesis: glucocorticoid inhibitory capacity as a function of the size of the more mature T cell subset.

The relationship between the expression of T3 and T6 antigens and the capacity to respond to phytohaemagglutinin (PHA) has been studied in the lymphocyte component of nine human thymomas. It appears that there is a positive correlation between the mitogen responsiveness of thymoma lymphocytes and the relative proportion of T3 positive (T3+), T6 negative (T6-), peanut receptor negative and IgM-Fc receptor positive cells. Moreover we have comparatively investigated the dexamethasone (Dex) inhibitory effect on the mitogenesis of T lymphocytes from thymoma, normal thymus and peripheral blood. In the presence of the macrophage product interleukin 1, the capacity of Dex to inhibit the mitogenesis of peripheral blood purified T cells (PBT) is inversely correlated with the PHA concentration used. Conversely, Dex completely (greater than 90%) inhibits thymocyte mitogenesis irrespective of PHA concentration. The entity of Dex inhibitory effect on thymoma lymphocyte mitogenesis shows a great variability ranging between that observed in normal thymocytes and that observed in PBT. In each thymoma case the degree of inhibition appears to be dependent on the size of the more mature thymocyte pool being positively correlated with the number of T6+ but negatively with that of T3+ cells. Our data demonstrate a high degree of variability among thymomas relative to the phenotypic and functional properties of their lymphocytic component. On the other hand, in some thymomas the phenotypic and functional characteristics of lymphocyte component seem to represent only a narrow span of normal thymocyte maturative pathway. In this respect, human thymoma may constitute a profitable tool for studying the intrathymic T lymphocyte maturative steps.

Adult↗