The authors report their studies on the cross-reactivity of certain anti-DNA antibodies with polypeptides expressed on the membrane of different cell types. These lupus associated membrane proteins (LAMPs) could play an important role in the pathophysiology of systemic lupus erythematosus (SLE) since anti-LAMP antibodies have been found in renal eluates of MRL/lpr/lpr mice and in the serum of patients with active SLE.