T-bet, pSTAT1 and pSTAT3 expression in peripheral blood mononuclear cells during pregnancy correlates with post-partum activation of multiple sclerosis

In pregnant women affected by multiple sclerosis (MS) we observed increased percentages of CD4+CD25+Foxp3+ T regulatory cells at the 1st and the 2nd trimester of gestation that was associated with a decreased T-bet expression in CD4+ T cells.In women showing clinical relapse and/or new lesions at MRI after delivery we found, a higher expression of T-bet, pSTAT1 and pSTAT3 in CD4+, CD8+ T cells and CD14+ cells, associated with an increase of IFNγ and IL17 production by PBMC at the 3rd trimester of gestation and after delivery.Our data suggest that the expansion of circulating CD4+CD25+Foxp3+ regulatory T cells and the lower expression of T-bet in CD4+ T cells may account for the decreased MS activity during pregnancy. The expression of T-bet, pSTAT1 and pSTAT3 in peripheral blood CD4+ and CD8+ T cells and monocytes could be useful to identify MS patients who will develop a relapse after delivery.