The role of the 16/6 idiotype network in the induction and manifestations of systemic lupus erythematosus

Experimental systemic lupus erythematosus (SLE) has been induced in mice by immunization with either a human anti-DNA mAb bearing a common idiotype (Id) designated 16/6 Id (antibody 1, Ab1) or with a murine anti-16/6 Id mAb (Ab2). In the present study a murine mAb (5G12-4, Ab3) that bears the 16/6 Id and binds to DNA was produced and was found to bind rabbit anti-16/6 Id sera and murine antl-16/6 Id mAb similarly to the human mAb 16/6 Id (Ab1).Moreover, mAb 5G12-4 was shown to share T cell epitopes with the human 16/6 Id mAb, since lymph node cells of mice immunized with the mAb 5G12-4 proliferated significantly to the human 16/6 mAb and vice versa. Following immunization of mice with the murine mAb bearing the 16/6 Id, antibodies to dsDNA, ssDNA, 16/6 Id, anti-16/6 Id, and to HeLa nuclear extract proteins were detected, similarly to those observed previously upon immunization with Ab1 or Ab2. Six months following the immunization, the mice exhibited leukopenia, increased erythrocyte sedimentation rates, and proteinuria. Examination of the kidneys of the mice disclosed immune complex deposits, thickening of the Bowman's capsule and glomerular necrosis. These results show the Importance of the 16/6 Id network in the induction and progression of SLE in mice.