Mucosal immunity in sexually transmitted infections

Although the immune compartment of the genital tract is considered a component of the common mucosal system, it displays distinct features characteristic of its physiological and immunological needs not shared by other mucosal sites. These include marked differences in the phenotypes of epithelial cells, lymphocytes, macrophages and dendritic cells, as well as isotype distribution and origin of antibodies in genital tract secretions. The absence of organized inductive lymphoepithelial mucosal tissues analogous to those present in the intestinal and respiratory tracts compromises the induction of vigorous immune responses not only to agents of sexually transmitted diseases, but also to allogeneic sperm and a semi-allogeneic fetus which are essential for species survival. Furthermore, based on studies of the induction of humoral and cellular immune responses and their pronounced hormonal regulation, it has become obvious that future immunization strategies must consider the uniqueness of the genital tract immune system.