Immunoreactivity to intra- and extracellular antigens is regulated mainly by two different types of T-helper cells, namely TH1 (producing mainly IFN-gamma and Il-2) and TH2 (producing IL-4, -5, -10). Both types cross-regulate each other. TH1 mechanisms seem to be involved principally in organ-specific autoaggressive disorders, while TH2 response is an expression of allergic conditions characterized by eosinophilic reactions and increased IgE levels. There are only a few reports dealing with cytokine profiles in patients with primary biliary cirrhosis (PBC). From studies analyzing the cytokine gene expression and cytokines in supernatants of nonstimulated and antigen-specific lymphocytes derived from the affected liver or peripheral blood of PBC patients, there is evidence that, in the course of the disease, predominantly TH1 cells are activated. However, in view of the eosinophilic reaction observed especially in patients with early PBC, it may well be that a switch from TH2 to TH1 occurs. Concerning the regulatory function of TH1/TH2 cells, a more refined evaluation of these T-cell subsets could help to provide a new insight into the natural course of PBC.