"Autoimmune disease occurs when an immune response attacks our own tissues. Like all adaptive immune responses, it is focused on specific antigens by T-cell receptors and B-cell receptors. In contrast to infection, the antigens that these cells recognise are processed from proteins within the target organ and this drives a chronic inflammatory process that disrupts the normal function of the tissue. In human diseases the trigger for this process cannot usually be determined. There is evidence that autoimmunity can follow infection, but that more than one infection can initiate disease. Other environmental factors are also relevant but are not well defined"-- Provided by publisher.