Cutting edge: reversal of murine lupus nephritis with CTLA4Ig and cyclophosphamide.

Cyclophosphamide (CTX) prevents progression of nephritis and prolongs survival in (NZB x NZW)F(1) (B/W) mice and is used to treat humans with lupus nephritis. To compare the efficacy of CTLA4Ig with CTX and determine whether there is an incremental benefit to combining CTLA4Ig with CTX, we treated B/W mice with CTX, CTLA4Ig, or both agents. In mice with mild renal disease, treatment delayed the onset of proteinuria and prolonged survival in all groups. In mice with advanced renal disease, treatment with both agents reduced proteinuria in 71% of mice, whereas mice treated with either agent alone had no such improvement. Survival was also markedly improved among mice treated with both agents. Thus, combination treatment with CTX and CTLA4Ig is more effective than either agent alone in reducing renal disease and prolonging survival of B/W mice with advanced nephritis. This striking reversal of proteinuria is unprecedented in animal models of SLE.