Although dendritic cells and macrophages have been shown to secrete less inflammatory cytokines after Pioglitazone-mediated PPARγ activation [2,6], our experiments indicate that the effect of Pioglitazone administration on single isolated hepatic immune cell populations cannot predict the influence of pharmacologic PPARγ activation in vivo in an experimental model of hepatitis. The gene discussed is PPARG; the disease is hepatitis A virus infection.