NORADRENERGIC MODULATION OF LYMPHOHEMATOPOIESIS

Adrenergic agents can affect hematopoiesis after syngeneic bone marrow transplantation (BMT) in mice. In particular, chemical sympathectomy by 6-hydroxydopamine and/or administration of various doses of the al-adrenergic antagonist prazosin were shown to increase the concentration of blood granulocytes, platelets and bone marrow granulocyte - macrophage-colony forming units (GM-CFU), and to induce a granulocytic hyperplasia of the spleen. Here we show that while enhancing myelopoiesis, prazosin decreased the number of spleen B- and T-lymphocytes as well as the number of thymocytes after BMT. The relative proportion of thymocyte subpopulations was not affected, suggesting a non-corticosteroid related mechanism. Furthermore, NK activity and primary cytotoxic T-lymphocyte (CTL) response to Lancy vaxinia virus was impaired in mice treated with prazosin after BMT. When noradrenaline was added in bone marrow cultures, it decreased the number of GM-CFU and such an effect was counteracted by prazosin. These findings suggest that hematopoiesis is under an alpha-adrenergic control.