Pregnancy and lactation induced suppression of cell mediated immunity

The effect of pregnancy and lactation on effector or killer cell responses of syngeneically bred BALB/c (H-2d) female mice to the EL4 (H-2b) tumor and C57BL/6 (H-2b) female mice to the P815 (H-2d) tumor was evaluated with cell mediated cytolysis (CMC). Virgin age correlated females served as controls. Maternal spleen cell responses to the tumor were depressed at 10-15 days of pregnancy and during lactation at 1-5 days and 10-20 days postpartum. One to five days after weaning the maternal response began to increase again. In this study the greatest suppression of the response occurred at 1-5 days postpartum. The route of tumor sensitization, i.e. intraperitoneal or subcutaneous, did not make a difference in the depression of the maternal response. Serologic evaluation of splenic cell populations with anti-Thy 1.2 serum did not indicate differences which could account for the suppressed maternal CMC response.