To determine the role of the cytokine activin A in the regulation of human T follicular helper (Tfh) cell gene program, we performed a transcriptomic analysis (RNA-seq) of human naïve CD4 T cells differentiated in vitro with activin A. The analysis of the gene expression profile driven by activin A, alone or in combination with IL-12 (a know regulator of human Tfh differentiation/function), revealed that activin A can regulate the expression of multiple molecules involved in the differentiation and/or function of human Tfh cells. Human naïve CD4 T cells were isolated from fresh PBMCs of healthy control subjects by magnetic bead isolation. Purity was measured by FACS as percentage of CD4+CD45RA+ cells and was 95% or higher. Upon isolation, naïve CD4 T cells were stimulated with anti-CD3/CD28 coated beads in the presence of the following cytokine combinations: no exogenous cytokines (beads only), activin A, IL-12, activin A+IL-12, TGFb, TGFb +IL12. Following 5 days of in vitro culture, live CD4 T cells were FACS sorted and gene expression was analyzed by RNA-seq. Data are from independent donors.