Lymphocyte cyclic AMP levels antepartum and postpartum as an indirect assessment of the immune system during pregnancy.

The literature dealing with the immunological state of the pregnant woman has been conflicting. The concentrations and activity of a number of hormones and proteins which modify lymphocytic activity have been measured both in vivo and in vitro during pregnancy. Most of the differences between reported studies can be reconciled to technical or experimental variations. In some instances, the purported suppressive effects of embryonic proteins such as HCG have actually been caused by the impurity of the preparation studied. We have attempted to approach the question of whether or not the pregnant woman is immunosuppressed by studying a regulatory material in the lymphocytes. It is known that cAMP is a mirror of lymphocytic activity and that low levels of cAMP may indicate a high degree of reactivity, while high levels are present when lymphocyte reactivity is low. In an initial study, ten women volunteered to have blood drawn in the last trimester and two months postpartum. Cyclic AMP was extracted from lymphocyte-enriched leukocytes and stored until all samples were available from all patients so that the analysis could be made simultaneously. Five samples were obtained from healthy nonpregnant women in the same age range. Postpartum and nonpregnant women were found to have significantly elevated levels of cAMP as compared to the lymphocytes obtained in the third trimester of pregnancy. The experiments were then repeated using seven more patients. The same significant increase in postpartum lymphocyte cAMP concentrations were found. The precise reason(s) for this is not known, but may be due to increased suppressor cell activity.