Unique Skin Immunology of the Lower Female Genital Tract with Age

Abstract

It has been long recognized that the genital tract must be able to defend against significant microbial exposures. In this area of medicine, old theories that may have even acquired some attributes of folklore must be revised to include new knowledge. Through the last century, popular ideas regarding mechanisms of microbial defenses in the genital tract have reflected the medical thinking of each era. In the time of antisepsis of the early twentieth century, lactic acid from the lactobacillus was proposed as the chief regulatory vaginal antiseptic. Subsequently, the possibility of antiseptic action from hydrogen peroxide-producing lactobacilli was considered, although little hydrogen peroxide would be expected to be produced in the naturally anaerobic environment of the vaginal lumen. With the influence of the more recent antibiotic era, research interest has focused upon bacteriocins, unique but relatively weak lactobacillus-derived antibiotics. Theories of microbial defense have evolved further in the current, more enlightened era of immunology. Rapid advances in the area of immunology have now disclosed complex immune defenses in the genital epithelium that do have a significant antimicrobial impact, moderated by estrogen. From the immune standpoint, the lower genital tract has the following competing roles: (1) to facilitate the various aspects of reproduction and (2) to simultaneously prevent the access of locally resident microbes to the upper genital tract and to the peritoneal cavity. To facilitate a primary function in reproduction, the immune responsiveness of the lower female genital tract is blunted. Ovulation, fertilization, pregnancy, labor, and delivery of the infant are all mediated by immune mechanisms that may not be optimal for microbial defense. A blunted humoral immune response may be compensated by an active innate or cellmediated response. For example, sperm may be highly immunogenic. If sperm are detected by the humoral immune system, the development of antisperm antibodies can reduce fertility [1]. It is important for the vaginal immune system to identify potential pathogens, but not