IL-4−/− mice immunized with TFA-JHDN-5 developed significantly less hepatitis and TFA and CYP2E1 autoantibodies than did BALB/c mice (Fig. 3A to C), suggesting that IL-4 promotes TFA-JHDN-5-induced hepatitis and antibodies, a finding similar to that in our prior studies (9). Here, IL4 is linked to hepatitis A virus infection.