URINARY C5B-9 EXCRETION AND CLINICAL COURSE IN IDIOPATHIC HUMAN MEMBRANOUS NEPHROPATHY

Recent reports suggested that the presence of terminal complement comp lex (C5b-9) in urine from patients with idiopathic membranous nephropa thy (IMN) may indicate on-going immunological damage. This report docu ments the relationship between C5b-9 excretion and clinical outcome in 35 adult patients with biopsy-proven IMN and progressively declining renal function. There were two groups of patients. Group I received on e of three treatment regimens: prednisolone alone, prednisolone and ch lorambucil, or prednisolone and cyclophosphamide (N = 22). Group II re ceived no immunosuppressive therapy (N = 17). Three of the 18 patients receiving immunosuppressive drugs had more than one treatment regimen as they experienced a clinical relapse during the study period; hence 22 treatments were available for analysis. Urine samples were collect ed regularly and urinary C5b-9 (uC5b-9) was determined by ELISA. Both groups were similar with respect to age, sex distribution, and the dur ation of follow-up. An improvement in proteinuria and creatinine clear ance was noted in the immunosuppressed group. Thirty-five patients wer e excreting C5b-9 initially (18 from group I and 17 from group II); 17 patients continued to excrete C5b-9 at the end of the observation per iod. These 17 patients had a significantly worse clinical outcome when compared to the 18 patients whose C5b-9 excretion became negative, ei ther spontaneously or with treatment (P < 0.005). These results indica te that continuing C5b-9 excretion is correlated with a poor clinical outcome. They also suggest that uC5b-9 is a dynamic marker of ongoing immunological injury, and therefore may be useful in the initial asses sment and monitoring of patients with IMN and in identifying patients who may derive benefit from immunosuppressive therapy.