Diminished hepatitis in IL-6-deficient, anti-IL-6 receptor α-treated, ovariectomized, or male mice; undetectable IL-6 levels in splenocyte supernatants from ovariectomized and male mice; elevated splenic IL-6 and serum estrogen levels in castrated male mice, and IL-6 induction by 17β-estradiol in splenocytes from naïve female mice (p<0.05) suggested that 17β-estradiol may enhance sex bias through IL-6 induction, which subsequently discourages Treg survival. The gene discussed is IL6; the disease is hepatitis A virus infection.