Cell-Mediated Immunity in Human Pregnancy

Changes in Lymphocyte Reactivity during Pregnancy and Postpartum

Abstract

The function of thymus-dependent lymphocytes (T lymphocytes) was studied in women during pregnancy and labor and postpartum by evaluating the blastogenesis of peripheral lymphocytes, which were stimulated with phytohemagglutinin-P (PHA-P) in both whole-blood semimicroculture and purified lymphocyte culture. Data from 353 random samples (203 women) and 50 serial specimens from 10 women revealed that PHA-P induced-lymphocyte blastogenesis was significantly (p<0.005) reduced during pregnancy and labor but rapidly returned to normal several days after artificial termination in the early stage of pregnancy as well as after full-term delivery. These results indicate that the T-lymphocyte function in maternal peripheral blood is depressed by causes related to pregnancy. It seems very likely that depressed T-lymphocyte function during pregnancy is caused by inhibitory factors in the blood plasma derived from the feto-placental unit. Questions relating to the inhibitory factors in maternal plasma are discussed.