ABSTRACT
Although long considered as immunologically incapable of supporting an active immune response against locally encountered antigens (perhaps as perception of the fact that it must tolerate semen antigens), the female reproductive tract mucosa has been shown to contain all cell populations required for initiating an immune response. HLA-DR + Langerhans cells with elevated antigen presentation capability have been identified in the vaginal and cervical epithelia, being most abundant in the vulval epithelium. Intraepithelial T-cells have been found at all sites and comprise primarily CD8+ cells. A significant proportion of these cells express TIA-I [I), suggestive of a cytolytic capacity. In contrast, CD4+ T-cells are rarely found in these epithelia but predominate in the submucosa of the vagina, cervix, and Fallopian tubes. Remarkably, the proportion of CD4+ and CD8+ T-cells may vary in the tissue districts. Although all components of the mucosal immune system are present in the female reproductive tract, the precise sites of induction of secretory immune responses in this organ are largely unknown. Moreover, even large differences in the cellular composition and distinct phenotypes have been reported in the same genital district of the different mammals. An example is the very different proportion of CD4+ and CD8+ T-Iymphocytes in the subepithelial layers of mouse and rat vagina [2,3).
