PSG6 is a pregnancy-specific glycoprotein(PSG). PSGs are secreted proteins produced by the rodent and primate placenta and play a critical role in pregnancy success. The levels of PSGs are highest during the third trimester of pregnancy, a time marked by the most profound suppression of MS disease attacks. PSGs regulate T-cell function. The regulation of T-cell function during pregnancy is likely the result of significant hormonal changes and may well involve immunoregulatory proteins derived from the placenta. Pregnancy specific glycoproteins (PSGs) are the most abundant placentally derived glycoproteins in the maternal serum. PSG1, PSG6, PSG6N, and PSG11 induce dose-dependent secretion of anti-inflammatory cytokines by human monocytes. Human and murine PSGs exhibit cross-species activity.