T-lymphocyte subpopulations in pregnancy.

T-lymphocyte subpopulations were evaluated in 44 pregnant women at different stages of gestation by means of monoclonal antibodies. A total of 32 healthy women of the same age served as a control group. OKT3-positive cells (more than 95% of the circulating T-lymphocytes) decrease markedly in pregnancy between the 14th and the 28th week. Such a decrease seems to be due to a specific lowering in the number of OKT4-positive cells (which seem to represent helper T-lymphocytes). OKT8-positive cells (which seem to represent cytotoxic-suppressor T-lymphocytes) show no meaningful alteration. Possibly due to helper decrease, maternal immunity is impaired between the 14th and 28th week.