Maternal immunocompetence. I. The graft-versus-host reactivity of lymphocytes from pregnant rats and the distribution pattern of 51Cr-labeled lymphocytes in pregnant mice.

Lymphocytes from the peripheral blood, spleen, or para-aortic lymph nodes of prrimigravida L rats carrying (L X BN) F1 (LBN) fetuses are fully capable of mounting graft-versus-host (GVH) reactions in LBN F1 recipients. The reactivity of lymphocytes from interstrain pregnant (L X BN) or intrastrain pregnant (L X L) rats, or from rats postpartum from these pregnancies, is equivalent to that of normal virgin females over a full dose-response curve, ruling out both specific and nonspecific effects of pregnancy on the intrinsic GVH competence of the maternal thymus-derived (T) lymphocyte. Attempts to block GVH reactivity with serum from pregnant rats were unsuccessful. In addition, when the distribution pattern of 51Cr-labeled syngeneic and semiallogeneic lymphocytes was studied in intact primigravida mice, there was no difference between interstrain and intrastrain pregnant mice, and there was no evidence of immunologically specific 'trapping' in the para-aortic lymph nodes draining the interstrain pregnant uterus.