Clinical implication of recent advances in our understanding of IL-17 and reproductive immunology.

The identification of a novel helper T (Th)-cell subset, the IL-17-producing Th (Th17) cells, has provided new insight into our understanding of the molecular mechanisms of reproduction. IL-17 has an important role in induction of the protective immune response against extracellular bacteria or fungal pathogens. Th17 cells seem to participate in successful pregnancy processes. Th17 cells also play a pivotal role in pathogenesis of endometriosis, miscarriage, preterm labor and preeclampsia. Recent data show the reciprocal development of pathways between Th1/Th17 subsets and between Th17/Treg subsets, and the imbalance of Th17/Treg development has been reported in recurrent pregnancy loss and preeclampsia.