infection were depleted in Th17 functioning T cells. Role of Vitamin D The active form of vitamin D (1,25-Dihydroxyvitamin D3) has been found to 'severely impair' production of the IL-17 and IL-17F cytokines by Th17 cells. Thus, active form of vitamin D is a direct inhibitor for Th17 differentiation. In this way, oral administration of vitamin D3 was proposed to be a promising tool for the treatment of Th17-mediated diseases. In young patients with asthma 1,25-Dihydroxyvitamin D3-treated dendritic cells significantly reduced the percentage of Th17 cells, as well as IL-17 production. History of research Intensive research starting in 2004 in mouse models elucidated its transcription factors and the cytokines that provoke differentiation. References T cells