Immunological studies concerning the nephritis of systemic lupus erythematosus.

Antibodies were eluted from the isolated glomeruli prepared from the kidneys of 10 patients with the nephritis of systemic lupus erythematosus. Antibodies reacting primarily with buffer extracts of nuclei were eluted by acid treatment, and antibodies reacting mainly with DNA and nucleoprotein were eluted with deoxyribonuclease. Quantitative immunochemical studies revealed a high concentration of antinuclear antibody per milligram of gamma-globulin in glomerular eluates compared with that in the corresponding serums. The gamma-globulin of two eluates was found to consist predominantly of antinucleoprotein antibody. The selective elution of antinuclear antibodies was also indicated by the absence of other serum antibodies in the eluates. DNA antigen was demonstrated in the glomeruli of two kidneys with nephritis by means of isolated anti-DNA antibody labeled with fluorescein. In one of these cases, anti-DNA antibodies were also found concentrated in the glomeruli and, in the second, circulating anti-DNA antibodies were demonstrated in the patient's serum. The immunochemical evidence for the high specific activity of antinuclear antibodies and the association of DNA antigen with DNA antibody in glomeruli add further support for the antigen-antibody complex hypothesis for renal injury in systemic lupus erythematosus.