Immune complex infusion in the rat. Renal functional and morphological changes

Immune complexes were precipitated from pooled goat antisera to human Cohn Fraction II. After washing the complexes were solubilized in antigen excess. When complexes containing 10 mg of antibody were infused into saline-loaded rats an episode of oligoanuria lasting 4-6 hr resulted followed by transient proteinuria. By 24 hr after complex infusion protein excretion had returned to pre-infusion levels. With infusion of 5 mg of antibody similar functional alterations, though of lesser severity, occured. Control animals infused with Cohn fraction II alone in an amount and protein concentration equal to the experimental groups exhibited none of these features. Changes in blood pressure did not occur. Immune complex deposition was not detectable in the glomeruli by immunofluorescence microscopy. A mild microangiopathy affecting mainly interstitial vessels, with some glomerular endothelial cell swelling, was evident on light microscopy. It is suggested that circulating factors resulting from complex infusion rather than glomerular complex localization account for the changes observed.