Among the environmental factors that have been suggested as potential causative agents in PBC, particularly different bacteria have been discussed. In early histologic lesions in PBC, non-caseating granulomas are observed, as seen in other granulomatous liver diseases including sarcoidosis [1] , drug reactions, and, most interestingly, infections. Furthermore, non-caseating granulomas are unique to PBC when compared to other autoimmune pathologies. This has led to suspicion of a microbial basis for PBC [132] . In support of this hypothesis, certain bacteria were found to contain PDC components fully cross-reactive with the mammalian form. It was proposed that exposure to these homologues could trigger crossreactive immunity. In favor of a bacterial etiology, recent data suggest that Toll-like receptor ligands induce an augmented inflammatory response in PBC. In combination, presence of cross-reactive antigens in a proinflammatory environment would theoretically be able to break tolerance [133, 134] .