Is primary biliary cirrhosis a model autoimmune disease?

Primary biliary cirrhosis (PBC) has been coined a model autoimmune disease. In fact, it does share many similarities with other autoimmune diseases, but there are striking differences that illustrate the uniqueness of the immunopathology. Firstly, similar to other autoimmune diseases, there is an intense humoral and cellular response to an intracytoplasmic antigen. There is also an overlap of the epitopes recognized by autoreactive CD4⁺, CD8⁺ T cells as well as B cells. Patients with PBC are also predominantly female, and there is a higher family history of other autoimmune diseases. In contrast, however, there are no specific HLA associations in PBC. Further, there are no spontaneous or induced animal models of PBC. In addition, early in the biliary lesions of PBC, there is an eosinophilic infiltration and, often, there are granulomas. Finally, unlike several other human autoimmune diseases, patients with PBC have recognition of but one major epitope, and there is no evidence for determinant spreading. Hence, although the immune response of PBC has been vigorously defined, there remain major gaps in understanding the most difficult issue of all, namely etiology.