Regulation of Recombinase Rag-1 Expression by Female Sex Steroids in Treg and Th17 Lymphocytes: Role of Oncostatin M

The effect of estradiol (E₂), progesterone (P₄), and oncostatin M (OSM) on the differentiation of CD4⁺ T cells to T regulatory (Treg) lymphocytes and T helpers 17 (Th17) was investigated. The possibility of revision of the T cell receptor in these subpopulations by evaluating the expression of RAG-1 recombinase was also studied. E₂ at concentrations characteristic of pregnancy trimester I, but no P₄ or OSM, increased the Treg level. Combination of sex steroids with OSM increased the percent of CD4⁺FOXP3⁺ cells and enhanced RAG-1 expression in these cells, thus promoting the development of immune tolerance during pregnancy. In the study of Th17, such effect of the hormones and OSM was not detected.