Furthermore, Zhao et al. confirmed that Indirubin could significantly increase the quantity and percentage of CD4+CD25+Foxp3+ Tregs in the peripheral blood, spleen, thymus and lymph nodes of CITP mice [122], which was consistent with the earlier results reported by Zhang et al. [123] These findings further indicate that increasing the number of CD4+CD25+Foxp3+ Tregs and maintaining their immunosuppressive function may be critical for indirubin in improving the pathological state of ITP. Here, CD4 is linked to autoimmune thrombocytopenic purpura.