Serologic abnormalities in spontaneous and drug-induced systemic lupus erythematosus.

Extensive serologic changes occur in systemic lupus erythematosus (SLE) which are probably secondary to unknow primary cause(s). The New Zealand hybrid mouse model most likely has a viral-induced disease and does not show many of the clinical features of the human disease. The best example of human SLE which provides a clue to etiology is the drug-induced type, particularly that due to procainamide. In these patients it is possible to study the development of serologic changes prior to the onset of clinical manifestations, and then observe regression of the clinical and serological changes on withdrawal of the medication. Although there is a rough correlation between the many serologic abnormalities and the clinical picture, enough exceptions exist, so that single tests such as serum complement, anti-DNA antibodies, per cent DNA binding, and others, cannot be used as a sine qua non for management. Care of the patient still remains a clinical problem guided by various laboratory procedures but not dependent on any one. Alkyating agents have a limited role in the treatment of lupus nephropathy and cutaneous vasculitis but azathioprine is probably of no value in SLE.