Human vaginal leukocytes and the effects of vaginal fluid on lymphocyte and macrophage defense functions.

OBJECTIVES: The purpose of this study was to quantify, characterize, and further define the role of vaginal white blood cells in defense mechanisms and human immunodeficiency virus infection. STUDY
DESIGN: Vaginal lavages were obtained from five healthy women throughout three menstrual cycles. Lymphocyte subpopulations, macrophages, and granulocytes were characterized and quantified by an immunohistologic technique. Vaginal lavage fluid was added to peripheral blood mononuclear cells, and effects on cell viability, lymphocyte proliferation, macrophage phagocytosis, and expression of various cell surface molecules critical to immunologic functions were assessed. Data were analyzed by Student's t test.
RESULTS: Few lymphocytes were found at any stage of the menstrual cycle; however, granulocytes and macrophages were abundant at menstruation and present at low levels through the proliferative phase. Vaginal lavage fluid collected during menses, at midcycle, and after coitus suppressed mitogen-induced lymphocyte proliferation but had no effect on surface expression of human leukocyte antigen or CD4 antigens, or on macrophage function. Likewise, low pH (less than 5.0) medium significantly inhibited lymphocyte proliferation but had no effect on macrophage phagocytosis. The spermicide nonoxynol 9 was toxic to both lymphocytes and macrophages.
CONCLUSION: White blood cells, including lymphocytes and macrophages, are infrequently present in cervicovaginal secretions of healthy women except during menses; the vaginal environment may effect their function.