T and B lymphocytes in pregnant women.

The peripheral blood of 27 women in their third trimester of pregnancy and of 16 control subjects was studied for total WBC counts and total numbers and percentages of T and B lymphocytes, including quantitation of the major immunoglobulin subtypes of the B lymphocytes. Although significant differences were found for percentages of total lymphocytes, T Lymphocytes, and B lymphocytes, the absolute numbers varied only slightly between the 2 study groups. A higher percentage and a higher absolute number of IgG-bearing B lymphocytes were found among pregnant women than among controls. It is concluded that significant quantitative alterations in circulating T and B lymphocytes do not occur in the third trimester of pregnancy; therefore, the concept of impaired cellular immunity, which has often been suggested to occur in this setting, is not supported. A review of the literature on T and B lymphocytes in human pregnancy is presented.