Prostaglandins, cyclic AMP production and biological activity of alloimmune thymocytes

The effect of alloimmunized non-adherent thymocytes on the spontaneous activity of the mouse atria was studied. BALB/c anti C3H non-adherent thymocytes induced negative inotropic effect on C3H atria. Cell-free supernatant from non-adherent thymocytes induced the same biological activity. This activity was blunted by the inhibition of non-adherent immune thymocytes' cyclo-oxygenase activity. PGE was present in higher amounts in free-cell supernatant from BALB/c anti C3H thymocytes plus C3H atria than in those from non-immune thymocytes. Intracellular levels of immune thymocytes cAMP are raised in comparison with those of normal thymocytes. It is proposed that alloantigen stimulates non-adherent thymocytes, increasing intracellular levels of cAMP and PGE. Immune thymocytes, release PGE upon recognition of the alloantigens expressed in the atria and this triggers a negative inotropic effect. The increment in immune thymocyte cAMP appears to be associated with the activation of thymocytes cyclo-oxygenase activity by alloimmunization.