Assay and characterization of polyanion--immunoglobulin complexes in sera of New Zealand Black mice.

Polyanion—immunoglobulin complexes, considered important factors in the pathogenesis of glomerulonephritis common in systemic lupus erythematosus, were found and isolated from sera of NZB mice by selectively binding them to an anion-exchange cellulose (DE52). Accurate quantification of such complexes was possible, in terms of immunoglobulin content, by means of an antiglobulin complement-fixation assay. In sera of NZB mice the concentration of immune complexes increased up to about 11 months of age and then it declined, whereas in the sera of the C57B1 and HaICR strains of mice, which do not develop spontaneous glomerulonephritis, the concentration was lower initially but increased steadily with increasing age and reached an equivalent level at about 27 months. The complexes were composed primarily of immunoglobulins of the IgG class bound to native DNA. The finding of significant levels of circulating immune complexes in mouse strains without renal disease suggests that such complexes, although necessary, might not be sufficient and solely responsible for overt glomerulonephritis.