FK-506 prevents diabetes in diabetes-prone BB/Wor rats

The effect of the immunosuppressant FK-506 on the development of diabetes in BB/Wor rats was investigated. Using a treatment schedule (25 micrograms i.m. from day 27 to 120), not associated with detectable general ill effects, this drug was found to completely inhibit the appearance hyperglycemia and to reduce the histological signs of pancreatic insulitis. The treatment was also able to reduce the percentages of Ia+ T-lymphocytes and to block the appearance of detectable serum levels of gamma interferon (IFN).

Anti-endothelial cell antibodies in patients with Wegener's granulomatosis and micropolyarteritis

Anti-endothelial cell antibodies (AECA) have been detected by cell surface radioimmunoassay in nine out of 15 patients with micropolyarteritis (MPA) and in two out of five patients with Wegener's granulomatosis. AECA mostly belonged to the IgG isotype and were present in the active phase of the diseases. These antibodies were not detectable in 10 sera from patients with essential mixed cryoglobulinaemia, suggesting that they were not a mere epiphenomenon consequent to the inflammatory vascular injury. The binding activity was not related to ABH antigens or to HLA class I antigens displayed by resting human endothelial cells in culture and was not influenced by removing immune complexes. Absorption of the anti-neutrophil cytoplasmic antibodies (ANCA), present in MPA and Wegener's granulomatosis sera, did not affect the endothelial binding. AECA-positive sera did not display lytic activity against endothelial cells, neither alone nor after addition of fresh complement or normal human peripheral blood mononuclear cells. Although AECA are not cytolytic for endothelial cell monolayers in vitro, the reactivity against intact endothelial cells suggests their possible involvement in in vivo pathological processes affecting vascular structures in small vessel primary vasculitides.

Synergisms between different activation pathways in adult and aged human lymphocytes

The present report investigates the synergistic effects of different agents (phytohaemoagglutinin (PHA), anti-CD3, phorbol-12-myristate-13-acetate (PMA) and Ionomycin on T cell activation. Results indicate that in normal lymphocytes PMA causes a dose-dependent decrease of PHA-induced blastogenesis and a marked enhancement of anti-CD3-induced 3H-thymidine uptake. There is positive synergism when cells are costimulated with PMA and the calcium ionophore Ionomycin. These data show that phorbol esters can exert either positive or negative synergisms depending on the experimental conditions. We also studied the simultaneous stimulation with PHA and anti-CD3 which gives an addictive effect for the minimal doses of the two stimuli, and an appreciable negative synergism for their highest concentrations. In order to evaluate T lymphocyte functions in the age-associated immune defect, PHA plus anti-CD3 and PMA plus Ionomycin costimulation assays were applied to a population of healthy elderly subjects. An additive effect is found after costimulation with the highest doses of PHA and anti-CD3, at variance with the negative synergism found in younger adult controls. Following costimulation with PMA plus Ionomycin, elderly subjects also display an impaired response, as compared to adult controls. No correlation was found with PHA-, anti-CD3- and PMA plus Ionomycin-induced T cell proliferation. These results underline the complexity of age-associated immune defects and suggest that alterations in different mechanisms of lymphocyte activation are responsible for the immune deficiency of aging.

In vivo immunopotentiating activity of thymopentin in aging humans: modulation of IL-2 receptor expression

The effect of thymopentin treatment was investigated in immunocompromised elderly subjects. Thymopentin was able to increase IL-2 production and IL-2 receptor expression, as assessed on PHA-activated blasts by percentage of Tac-positive cells and response to exogenous IL-2. After treatment, an increased precursor frequency, estimated by limiting dilution analysis, of PHA-responding lymphocytes was observed in two out of six subjects tested. In vitro experiments with thymopentin show that the drug was able to enhance blastogenesis by PHA of elderly lymphocytes but not of adult cells. These results indicate that (a) the increased IL-2 synthesis/IL-2 receptor expression may be the crucial mechanism of the immunopotentiating activity of the drug in elderly subjects and (b) an increased intrinsic T-cell responsiveness seems to be responsible for this immunopotentiating activity, although an increase in the size of the responsive T-cell pool could not be excluded.

Heterogeneity of immune responsiveness in healthy elderly subjects

We studied a group of healthy elderly subjects (satisfying the SENIEUR Protocol admission criteria), chosen as a model of age-associated immune deficiency on the basis of their reduced skin reactivity to recall antigens. Results show that aged subjects, taken as a whole, display impaired T-cell functions: reduced blastogenetic responses to mitogens, IL-2 production, responsiveness to exogenous IL-2, and percentage of Tac positive blasts. However, the age-associated immune defect shows a wide range of impairment, even in a relatively homogeneous group of anergic/hypoergic subjects. In fact, a considerable proportion of our elderly subjects displays responses comparable with those of adult controls. These observations suggest that (a) immune deficiency is not a characteristic of aging per se; (b) cutaneous delayed hypersensitivity is not a criterion sensitive enough to identify people with age-associated immune deficit; and (c) more than one test is required to evaluate T-cell impairment in aging.

Interleukin 2 enhancement of anti-T3-induced lymphocyte activation: standardization and use of this model in immunocompromized elderly subjects

Anti-T3-induced T cell activation was standardized in human peripheral blood lymphocytes with respect to dose response, time kinetics and effect of exogenous IL-2 on blastogenesis and on IL-2 receptor expression, identified by anti-Tac monoclonal antibody. IL-2 was able to significantly increase 3H-thymidine uptake and Tac antigen expression in unstimulated and anti-T3 activated lymphocytes. This enhancement was more evident in cultures stimulated with non-mitogenic concentrations of anti-T3, supporting the hypothesis that these concentrations sensitize T cells to the Tac-inducing effects of IL-2. This model of lymphocyte activation was then applied to selected immunocompromized elderly subjects. The aged subjects showed depressed blastogenetic responses and Tac antigen expression, which were not corrected by prolonging the time of cultures. Aged lymphocytes showed a good response to costimulation with anti-T3 and IL-2, suggesting that at least for the anti-T3 activation pathway they are able to respond to IL-2 signals.

Effect of subcutaneous thymopentin treatment in drug addicts with persistent generalized lymphadenopathy

The effect of thymopentin treatment on the immune defects in drug addicts with persistent generalized lymphadenopathy and HTLV-III infection was investigated. Thymopentin was administered subcutaneously at two different dose schedules: 50 mg three times a week for 3 weeks (first cycle) and 50 mg/week for 3 months (second cycle). After the first cycle an increased number of OKT4+ lymphocytes and an improvement of PWM-induced blastogenesis and IgG synthesis in vitro was observed. The second cycle was unable to modify the same immune parameters in vitro. The treatment had no effect on the PHA responsiveness and on PHA-induced interleukin 2 production. The significance and the prognostic value of these findings are discussed in terms of the clinical evolution of the syndrome.

In vivo immunopotentiating activity of thymopentin in aging humans: increase of IL-2 production

The effect of thymopentin (TP-5) treatment on lymphocyte immune functions has been investigated in immunocompromised aged subjects. TP-5 was able to improve the cutaneous delayed hypersensitivity (CDH) to recall antigens and the proliferative response to phytohemagglutinin (PHA), concanavalin A, and Pokeweed (PWM) as well as the PHA-induced interleukin-2 (Il-2) production. On the other hand, no detectable changes were induced by TP-5 treatment either on PWM-induced immunoglobulin synthesis or on lymphocyte subsets identified by monoclonal antibodies. Our results suggest that the enhancement of Il-2 synthesis might be a crucial mechanism of the immunopharmacological action of TP-5 in aging humans.

Experiences with immunomodulant agents in HIV infections

Drug addicts with persistent generalized lymphadenopathy displayed the following immunological abnormalities: an inverted OKT4/OKT8 ratio, a depressed in vitro blastogenetic response to phytohemagglutinin and pokeweed mitogen (PWM), a reduced ability of PMNL to phagocytose and kill Candida albicans spores and to migrate in presence of a chemotactic factor. Thymopentin treatment (50 mg s.c. 3 times/week for 3 weeks and repeated after 3 months at 50 mg s.c. once a week for 3 months) improved OKT4+ lymphocytes (p less than 0.05) and the blastogenesis to PWM (p less than 0.01); moreover, at the end of the first cycle, the chemotaxis of neutrophils was increased to normal values.