Influence of pregnancy on dipeptidyl peptidase IV activity (CD 26 leukocyte differentiation antigen) of circulating lymphocytes.

Dipeptidyl peptidase IV (CD 26 leukocyte differentiation antigen) is an enzymic surface marker of a human T lymphocyte subpopulation which has been shown to be associated with their capacity to produce large amounts of interleukin 2 and proliferate strongly in response to mitogenic stimulation. The peptidase activity on the surface of purified human peripheral mononuclear cells was determined spectrophotometrically with the substrate glycyl-L-proline-4-nitroanilide. The peripheral mononuclear cells of pregnant women exhibited depressed mean dipeptidyl peptidase IV activity when compared with the activity of peripheral mononuclear cells from non-pregnant or male individuals. The gestational age (7 to 20 weeks) of the pregnant collective had no effects on peptidase levels. Women taking oral contraceptives had a slightly lower mean activity than the non-pregnant group not using contraceptives. Thus, reduced dipeptidyl peptidase IV activity of peripheral mononuclear cells might reflect impairement of cellular immunity during pregnancy.