The role of innate and adaptive immunity in endometriosis.

The innate and adaptive immune systems are the two key branches that determine host protection at all mucosal surfaces in human body, including the female reproductive tract. The pattern recognition receptors within the host that recognize pathogen-associated molecular patterns are expressed on the cells of the innate immune system. Rapidly reactive, theinnate immune system, responds immediately to the presence of infectious or other non-self agents, thereby launching an inflammatory response to protect the host until the activation of slower adaptive immune system. Macrophages, dendritic cells, and toll-like receptors are integral components of the innate immune system. In contrast, T-helper (Th1/Th2/Th17) cells and regulatory T (Treg) cells are the primary components of adaptive immune system. Studies showed that the growth and progression of endometriosis continue even in unilateral ovariectomized animal suggesting that besides ovarian steroid hormones, the growth of endometriosis could be regulated by innate/adaptive immune systems in pelvic environment. Recent reports demonstrated a potential role of Th1/Th2/Th17/Treg cells either individually or collectively in the initiation, maintenance, and progression of endometriosis. Herewe review the fundamental knowledge of innate and adaptive immunity and elaborate the role of innate and adaptive immunity in endometriosis based on both human and experimental data.