Analyses of dendritic cell subsets in pregnancy.
PROBLEM: Changes in the frequency of dendritic cell (DC) subsets in the peripheral blood were analyzed as pregnancy progressed, and the effects of human chorionic gonadotropin (hCG) on myeloid and lymphoid DC subsets were phenotypically and functionally examined. METHOD OF STUDY: Two major subsets of DCs were prepared from the peripheral blood by flow cytometry. Major histocompatibility complex class II molecules and adhesion/costimulatory molecules were examined before and after culture with hCG. hCG receptors on both DC subsets were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The frequency of myeloid DCs increased in the late stage of pregnancy, while that of lymphoid DCs gradually decreased. The addition of hCG (physiological concentrations in pregnancy) to cultures induced the maturation of both DC subsets in conjunction with increases in the expression of adhesion/costimulatory molecules, their stimulatory activities in allogeneic mixed lymphocyte/leukocyte reaction, and cytokine secretion (interleukin-12 and interferon-gamma). hCG receptors were found in both DC subsets by RT-PCR, suggesting that these stimulatory activities of hCG are mediated by hCG receptors on the DCs. CONCLUSIONS: hCG can modulate immune responses through the activation of myeloid and lymphoid DCs.