DNA/anti-DNA complexes: correlation of size and complement fixation.

The hydrodynamic sizes of antibody/3H-dsDNA immune complexes are correlated with their ability to fix complement in a red blood cell-complement linked binding assay. The results with PM2 dsDNA and a sonicated preparation (with a molecular weight of approximately 5.10(5) suggest that packing considerations are also important in the complement binding reaction. The relevance of these findings with respect to the role of antibody/dsDNA immune complexes in the pathogenesis of glomerulonephritis in systemic lupus erythematosus is discussed.