Cell-mediated immunity to HIV in the female reproductive tract

The majority of HIV infections occur via sexual transmission across a mucosal barrier. In the case of male-to-female transmission, HIV-susceptible target cells are abundant in the ectocervix and vagina but are also present in the upper reproductive tract (endocervix and uterus). While the mechanisms of HIV transmission in the female reproductive tract are an active area of investigation, cell-mediated immune responses in reproductive tissues have not been thoroughly characterized. HIV-specific CD8+ T cells are present in reproductive tissues, to some extent mirroring populations present in the blood and gastrointestinal mucosa. Innate natural killer (NK) cells and regulatory T cells are also present in the genital tract. Furthermore, there is mounting evidence that the female reproductive tract may be uniquely susceptible to infection at specific times during the menstrual cycle, due to hormonal regulation of both innate and adaptive immune responses. This review provides an overview of recent findings on cell-mediated immunity to HIV in the female reproductive tract.