Epstein-Barr virus-transformed lymphocytes from patients with bullous diseases produce autoantibodies to cytokeratins

Human cell lines obtained after Epstein-Barr virus transformation of lymphocytes from seven patients with bullous diseases (Bullous pemphigoid, Pemphigus) and five controls were screened for the production of autoantibodies against skin antigens. In five out of seven patients, the culture supernatants tested by indirect immunofluorescence on frozen sections of normal human skin and rabbit lip showed the production of autoantibodies with different specificities: basal epidermal cells, whole epidermis, Merkel cells, fibroblasts endothelial cells, etc. All autoantibodies were of IgM class and reacted with intracellular structures. Some of them were further tested by immunoblotting against epidermal keratins and were found to react with the main human epidermal keratins (56 to 67 kDa). In contrast, even when patients had circulating autoantibodies, no supernatant showed any reactivity against the antigens usually involved in these diseases, i.e., the dermoepidermal junction or the intercellular speces of epidermis. Supernatants from controls did not show any reactivity by immunofluorescence. The results demonstrated that human lymphoid cell lines obtained from patients with bullous diseases elicited the production of anti-intermediate filament autoantibodies known to occur spontaneously in normal patients. It is suggested that this phenomenon may be linked to the blistering conditions that provoke tissue destruction.