PDCD1 and autoimmune hepatitis: Interestingly, Aoki et al. reported that the loss of natural Tregs (characterized by the constitutive expression of FOXP3 gene) induces fatal autoimmune hepatitis (AIH) in neonatal thymectomized (NTx)-PD1−/− mice, due to migration of dysregulated follicular T helper (Tfh) cells from the spleen (15).