Complement activation products in the circulation and urine of primary membranous nephropathy.

BACKGROUND: Complement activation plays a substantial role in the pathogenesis of primary membranous nephropathy (pMN). C5b-9, C3c, MBL, and factor B have been documented in the subepithelial immune deposits. However, the changing of complement activation products in circulation and urine is not clear. METHODS: We measured the circulating and urinary levels of C1q, MBL, C4d, Bb, properdin, C3a, C5a, and sC5b-9, in 134 patients with biopsy-proven pMN, by enzyme-linked immunosorbent assay. All the plasma values were corrected by eGFR and all the urinary values were corrected by urinary creatinine and urinary protein excretion. Anti-PLA2R antibodies were measured in all patients. RESULTS: The plasma complement activation products were elevated both in the patients with and without anti-PLA2R antibodies. C3a levels were remarkably increased in the circulation and urine, much higher than the elevated levels of C5a. C5b-9 was in normal range in plasma, but significantly higher in urine. The urinary C5a had a positive correlation with anti-PLA2R antibody levels and urinary protein. The plasma level of C4d was elevated, but C1q and MBL were comparable to healthy controls. Positive correlations were observed between plasma C4d/MBL and urinary protein, only in the patients with positive anti-PLA2R antibodies but not in those without. The plasma level of Bb was elevated and had positive correlation with urinary protein only in the patients without anti-PLA2R antibodies. CONCLUSION: Complement activation products were remarkable increased in pMN and may serve as sensitive biomarkers of disease activity. The complement may be activated through lectin pathway with the existence of anti-PLA2R antibodies, while through alternative pathway in the absence of antibody.

[Kinetics of the complement subcomponent C1q production of peritoneal macrophages in NZB/W F1 female mice].

To clarify the role of local production (exohepatic) of complement on primary host defense mechanisms against microbial infections in the host who decreased the amount of complement in serum, the kinetics of the complement production by the complement-producing cells in exohepatic tissue was examined by measuring the amount of C1q, subcomponent of the first complement component, in cultured supernatant of the monolayer of peritoneal macrophages (PM phi) collected from 5, 15, 35, and 48 weeks-old female mice of NZB/W F1 (B/W F1). The C1q production of PM phi in B/W F1 mice showed remarkable decrease at 15 weeks-old. After that, however, the C1q producibility of PM phi recovered gradually and, at mice 48 weeks old, the complement produced finally exceeded the amount observed in mice 5 weeks-old, contrariwise the C1q values in serum were significantly lowering in the same aged mice. The increased production of C1q of PM phi was observed in both 35 and 48 weeks-old mice, of which the value corresponded with increase of anti-nuclear antibody titer in serum and of the amount of protein in urine. On female mice of ddY (control), the amount of C1q production of PM phi in 5 weeks-old mice was two-fold higher than that of 5 weeks-old B/WF1 mice. But at 15 weeks, the production showed a 1/2 decrease in that of mice 5 weeks-old and the decreased values were kept to 35 weeks-old.(ABSTRACT TRUNCATED AT 250 WORDS)