Acute effect of passive Heymann nephritis on renal blood flow and glomerular filtration rate in rat: the effect of infusion of F(ab')2 fraction of anti-FX1(A) antibody.

We have earlier shown that there is an immediate fall in renal blood flow (RBF) and glomerular filtration rate (GFR) during induction of passive Heymann nephritis (PHN) by infusion of rabbit antibodies towards rat renal brush-border antigens (anti-Fx1A). To investigate the role of complement activation in this stage of the disease, we infused the F(ab')2 fraction of anti-Fx1A (aFFab) in one group of rats and the F(ab')2 fraction of normal rabbit IgG in another group (controls). aFFab produced no hemodynamic changes when compared to controls. Sixty minutes after infusion of aFFab, RBF was 5.7 +/- 0.4 ml/min/g kidney weight (control 7.3 +/- 1.0, NS), after anti-Fx1A RBF was 3.2 +/- 0.7, p less than 0.05 compared to control. GFR after infusion of aFFab was 1.0 +/- 0.1 ml/min/g (control 0.8 +/- 0.1, NS), after infusion of anti-Fx1A 0.2 +/- 0.1 (p less than 0.02 compared to control). The blood pressure was unaffected by aFFab infusion, while there was a temporary fall in blood pressure to a minimal value of 76 +/- 4 mm Hg 10-20 min after infusion of anti-Fx1A (p less than 0.01 compared to control). Immunofluorescence studies showed granular immune deposits in the subepithelial region of the glomerular basement membrane as shown after infusion of anti-Fx1A antibodies. In addition, fluorescence was seen in the brush-border of proximal tubuli. The results indicate that the immediate fall in RBF and GFR during induction of PHN in mediated via activation of the complement system.