Impairment of lymphocyte sensitivity to prostaglandin E2 in cultures from patients with lymphoadenopathy associated syndrome.

Prostaglandin E2 (PGE2) appears to have an immunosuppressive role in human immunodeficiency virus (HIV) infection. Therefore, the effect was studied of PGE2 pretreatment of T lymphocytes from patients with lymphadenopathy associated syndrome (LAS) on the expression of CD25 and CD71 as well as plaque forming cell (PFC) generation in pokeweed mitogen (PWM)-driven cultures. The PGE2-treated or untreated T lymphocytes were cultured with B cells and monocytes in the presence of PWM. Both CD25 and CD71 expression were assessed with an immunofluorescence technique; PFC generation was tested by hemolysis. Before exposure to PWM, LAS lymphocytes showed activation as evidenced by high CD25 and CD71 expression and PFC generation. Pretreatment by PGE2 did not inhibit expression of activation markers and PFC generation in LAS cultures, in contrast to what happened in control cultures. Thus, LAS lymphocytes are activated in vivo and are less sensitive to PGE2 inhibition than normal lymphocytes.

A short incubation with PGE2 affects the proliferative response of T lymphocytes to PWM.

In this study we have investigated the role of PGE2 in the activation of human T lymphocytes by PWM. A preincubation of these cells with molar concentrations of the prostaglandin ranging from 10(-9) M to 10(-4) M is able to reduce the expression of IL-2R and CD71 on T lymphocyte membrane during the first days of culture, while the DR molecule which is expressed later in the same experimental conditions is not affected by the treatment of T lymphocytes with PGE2. The PGE2-induced inhibition of IL-2R and CD71 well correlates with the reduction of 3H-thymidine incorporation by T cells, indicating that a preincubation of T lymphocytes with PGE2 profoundly affects the proliferative apparatus of these cells when they are stimulated by PWM.

Prostaglandin E2-induced inhibition of the in vitro immune response by SRBC-stimulated human lymphocytes.

Exogenous PGE2 strongly inhibits the response of human lymphocyte cultures to SRBC. This effect is mediated through a T cell inhibition since non-T cells are not significantly affected. Indomethacin, which inhibits in this system lymphocyte endogenous PGE2 synthesis increases the in vitro immune response. The effect of indomethacin is overcame by exogenous PGE2. These data may be relevant for explaining the immunomodulatory role of PGE2 following antigen challenge.

Effect of prostaglandin E2 on pokeweed mitogen-activated human lymphocyte cultures.

It is shown that a short incubation of peripheral human lymphocytes with PGE2 is able to reduce the B cell differentiation induced by PWM. The target of PGE2 action appears to belong to T lymphocytes, since the treatment of non-T cells is uneffective in reducing the immune response. Both OKT4+ and OKT8+ subsets are sensitive to PGE2. Data concerning the role of endogenous as well as exogenous PGE2 either on unfractionated or fractionated OKT4+, OKT8+ and non-T lymphocytes are also discussed. The PGE2 inhibition on immunoglobulin synthesis in PWM-stimulated cultures seems to be mediated by a complex effect on both the T cell subsets.

[Functional phenotypic immunological aspects in patients with LAS/ARC]. / Aspetti immunologici fenotipici funzionali in pazienti affetti da LAS/ARC.

The parameters in antibody-positive with LAS/ARC and antibody negative drug-users have been studied. The results show that in the first group the lymphocyte profile and in vitro immunoglobulin production are greatly affected. In the second group only modifications about activation markers and PWM induced B lymphocyte differentiation are present.

Isolation and purification of fetal calf serum factor promoting mouse erythrocyte rosette formation.

This paper describes the isolation and purification of a dialyzable mouse erythrocyte rosette-promoting factor (MERF) contained in fetal calf serum (FCS). All rosette-promoting activity of FCS appears to be due to a low molecular weight, ribonuclease-sensitive material with biological activity promoting the expression of mouse erythrocyte receptors on a subset of human B lymphocytes.