Cell-mediated immunity to cytomegalovirus in pregnant women.

Employing the techniques of in vitro lymphocyte transformation (LTF) and complement fixation, cell-mediated immunity (CMI) and antibody to cytomegalovirus (CMV) were studied in pregnant and nonpregnant women. The LTF activity was determined by the whole blood microassay using four strains of CMV (AD-169 and its early antigen [EA], Davis, Veca, and Towne strains), and phytohemagglutinin (PHA). Lymphocyte transformation response to specific CMV antigens at 11-30 weeks of gestation and to nonspecific mitogen (PHA) in all pregnant and postpartum women were found to be significantly depressed compared with the nonpregnant women. The lower LTF responses to CMV antigen and PHA were found in specimens taken from pregnant women at 21-30 weeks of gestation. There were no significant differences in the mean complement-fixing (CF) antibody titers and the percentage of E-rosette-forming T lymphocytes between subjects in various stages of pregnancy. In addition, concanavalin A (Con A)-generated suppressor T cell activity was evaluated in pregnant and nonpregnant women. The suppressor effect of Con A-activated lymphocytes in the pregnant women was somewhat higher than in nonpregnant women. These observations suggest that CMV-specific suppression of cellular immunity may play an important role in reactivation of CMV in pregnancy.