Complement fixing immune complexes containing antinuclear antibodies in patients with systemic lupus erythematosus

Immune complexes (IC) in the sera of patients with systemic lupus erythematosus (SLE) were isolated using goat antihuman C3 and rabbit antihuman Clq immunoabsorbent columns. The sera from 12 patients with SLE were sequentially eluted from the columns with veronal buffer, 0.02 M EDTA, 0.5 M NaCl, and 1 M propionic acid. The isolated IC were analyzed for antinuclear antibodies (ANA) with an HEp-2 cell substrate. ANA were detected in 6 patients' eluates from the EDTA fractions and 2 patients' propionic acid fraction by the antihuman Clq column method. ANA were noted in 7 patients' isolates from antihuman C3 column, 6 EDTA fractions, and 2 patients' propionic acid fractions. The ANA showed speckled patterns in 6 patients and a diffuse pattern in 1. Our studies demonstrate complement fixing IC containing ANA can be detected in the sera of patients with SLE by isolation with the antihuman Clq and antihuman C3 columns.