Humoral and cellular autoimmunity in women with recurrent pregnancy losses and repeated implantation failures: A possible role of vitamin D

Women with recurrent pregnancy losses (RPL) and repeated implantation failures (RIF) have auto- and cellular immune abnormalities. Approximately, 20% of women with RPL have autoimmune abnormalities, particularly antiphospholipid antibodies (APA). In addition, these women have a higher prevalence of antinuclear antibody, anti-thyroperoxidase and anti-thyroglobulin antibodies, and other non-organ-specific autoantibodies. In women with RPL, the presence of autoimmunity is often associated with cellular immune abnormalities, such as increased NK cell levels and Th1/Th2 cell ratios. Vitamin D (VD) plays a major role in regulation of auto- and cellular immune abnormalities. VD deficiency is prevalent in women with RPL, and women with VD deficiency have increased auto- and cellular immune abnormalities as compared with women with normal VD levels. VD has immune regulatory effects on various immune effectors including T, B and NK cells. Potential therapeutic application of VD for RPL and RIF with auto- and cellular immune abnormalities should be explored.