Reduction of interleukin-2-receptor expression on retroplacental blood lymphocytes in human pregnancy

Retroplacental blood lymphocytes (RPL) in human pregnancy were studied for proliferative response induced by recombinant interleukin-2 (rIL-2) and anti-Tac positive cells before and after PHA stimulation for 24 hr and compared with peripheral blood lymphocytes (PBL) of the same donor. Proliferation of RPL induced by IL-2 was significantly lower than that of PBL in all of six cases. In addition, flow cytometry analysis of IL-2 receptors (IL-2R) revealed that IL-2R expression of RPL after stimulation with PHA for 24 hr was significantly less than that of PBL in three of four cases and that RPL showed significantly fewer IL-2R than PBL even at resting state in one case. These results suggest that RPL seem likely to be composed of reduced numbers of lymphocytes bearing IL-2R of non-Tac protein and to have impaired capacity for the acquisition of high-affinity receptors for IL-2.