Nature of immune complexes in autoimmune chronic active hepatitis

Immune complexes containing antinuclear antibodies have been observed in autoimmune chronic active hepatitis. Using a library of nuclear constituents (deoxyribonucleic acid, small nuclear ribonucleoproteins, and histones), we analyzed the antigens involved in formation of immune complexes. Immune complexes were defined in dissociation experiments, and after separation under dissociating conditions. Immune complexes composed of histones and immunoglobulin G were observed in four of nine immune complex-positive autoimmune chronic active hepatitis sera. Immune complexes containing the small nuclear ribonucleoprotein U1-RNP and immunoglobulin G were observed in two additional samples. Kidney eluates obtained from 2 patients with autoimmune chronic active hepatitis and membranous glomerulonephritis revealed enrichment of anti-U1-RNP, suggesting specific deposition of this antibody in complexed form. Circulating immune complexes containing histones were observed only in patients with autoimmune chronic active hepatitis-associated sicca syndrome; those containing U1-RNP were restricted to patients with autoimmune chronic active hepatitis associated with kidney disease.