T-cell activity in HLA-associated autoimmune diseases

Background. The existence of T-helper-1 (Th1) and T-helper-2 (Th2) subsets has been implicated in the regulation of several immune responses, and alte rations in the Th1/Th2 balance have been involved in autoimmunity. The pres ent study investigates the relative influence of Th1 and Th2 patterns in au toimmune responses in patients with HLA-associated autoimmune diseases. Methods. This study concerns 849 patients of both. sexes, suffering from se veral autoimmune diseases. Tissue typing for HUA antigens of Class I (A, B, C) and Class II (DR, DQ) was carried out in all patients by conventional s erologic methods, comparing results with frequencies detected in a normal p opulation. Many immunological tests were also done. In particular, lymphocy te subsets (CD4+, CD8+, CD3-HLA-DR+, NK cells, sIg+B cells) were detected w ith monoclonal antibodies by a fluorescent cytometer. The changes in freque ncies of T cell subsets were used to calculate the possible incidence of tw o effector phenotypes (TE-1; TE-2). Results. The results of the immunogenetic analysis confirmed the significan t HLA-associations in several diseases. The essential T-cell changes were a lso exposed, thus defining the incidence of T-cell phenotypes (TE-1=56.3%; TE-2=34.8%). This finding suggested a major impact of cell-mediated immunit y, as compared with that of antibody-mediated immunity. Conclusions. The anomalies of Th1/Th2 balance can impact autoimmune disease , and in many cases a Th2 response can prevent Th1-mediated autoimmunity, w hich is the most evident phenomenon in several HLA-associated diseases.