Cryoglobulins isolated from patients with acute post-streptococcal glomerulonephritis, fixed complement in vitro and were associated with inflammatory changes following intradermal administration to unsensitized guinea pigs. Intravenous administration to laboratory animals was followed by clinical and morphologic changes resembling anaphylactic shock or by glomerulitis with the deposition of human IgG but no host IgC on the glomerular basement membrane and in the mesangium. Gel filtration using Sephadex G200 of cryoglobulin solution dissolved in, and eluted with, barbital buffer yielded a single component in the macroglobulin fraction. Gel filtration chromatography using dilute acid yielded 2 components; a large molecular weight component which was not identified by chemical or immunologic methods and another fraction which had the same chemical composition as normal human IgG except for a lower sialic acid content. Streptococcal antibody was not detected in either fraction and streptococcal antigens were not localized in the glomeruli of animals that developed glomerulitis. These studies show that mixed cryoglobulins isolated from patients with acute post-streptococcal glomerulonephritis exhibit properties similar to those of antigen-antibody complexes and suggest that they may have a primary or secondary role in the production of glomerular injury.
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