The in vivo regulation of splenic T cell population by the prostaglandin-mediated system.

The effects of prostaglandins (PGs) on splenic T cell population, the generation of Con A-induced suppressor T cells, and antibody response to sheep erythrocytes were examined in mice in which the in vivo level of PG was regulated by indomethacin (INDO), an inhibitor of PG-synthesis, and exogenous PGE2. Inhibition of PG-synthesis enlarged the T cell population in the spleen and such an enlargement was due to an increase in Lyt-1+2+ and Lyt-1-2+ subsets. In this group, the induction of suppressor T cells was augmented, while the antibody response was suppressed. Elevation of the PG-level scarcely affected the size of the whole T cell population in the spleen but slightly increased a Lyt-1+2- subset. The production of suppressor T cells was disturbed, and the antibody response was augmented in this T cell population. Experiments using anti-Lyt antibody plus complement showed that Lyt-1+2+ subsets exhibited these distinctive activities between PG-decreased and PG-increased mice. A Lyt-1+2+ subset from mice with a high PG-level may be in an advanced stage of maturation compared with that from mice with a low PG-level under the promoting effect of PG on T cell differentiation. In vivo regulation of the PG-level appears to play an important role in the regulation of the T cell population and immune response.