Beneficial effects of non-depleting anti-CD4 in MRL/Mp-lpr/lpr mice with active systemic lupus erythematosus and microscopic angiitis

MRL/Mp-lpr/lpr (MRL/lpr) mice spontaneously develop lymphoproliferation and systemic autoimmune disease. The majority of mice in any cohort develop systemic lupus erythematosus (SLE) and up to a quarter of them develop a syndrome that resembles microscopic angiitis (NIPA). Both conditions are characterized by vasculitis, glomerulonephritis and autoantibody formation. Depleting anti-CD4 monoclonal antibody (mAb) treatment is ineffective in MRL/lpr mice after disease onset. The present study investigates the effects of a non-depleting anti-CD4 mAb in MRL/lpr mice with active SLE or MPA. This antibody increased survival compared to control Ig but did not prolong survival compared to non-treated mice. However, anti-CD4 significantly reduced lymphoproliferation in the mice and furthermore reduced the vasculitis component of the autoimmune disease following several weeks of treatment.