altered th17/treg ratio in recurrent miscarriage after treatment with paternal lymphocytes and vitamin d3: a double- blind placebo-controlled study

background: recurrent miscarriage (rm) affects 2-5% of pregnant women. paternal lymphocyte immunotherapy is a common treatment for rm patients but the outcome has not been consistent. therefore, combined therapy with other immunosuppressive drugs such as 1 a, 25-dihydroxy-vitamin-d3 (vitamin d3) may improve the outcome. objectives: to investigate the effect of vitamin d3 on the balance of two essential t cells subsets, t helper (th) 17 and t regulatory (treg) cells, which contribute to the immune tolerance during pregnancy. methods: the expression levels of cd4 and forkhead box protein 3 (foxp3) in treg cells, and the expression levels of cd4 and il- 17 in th17 cells, were evaluated pre- and 3 months post-immunotherapy in rm patients treated with a combination of paternal lymphocytes and vitamin d3 compared with rm patients receiving lymphocyte immunotherapy alone. results: vitamin d3 therapy decreased the frequency of th17 cells in addition to reducing the th17/treg ratio in peripheral blood of rm patients compared with the control group (p