Abstract
Circulating immune complexes (CIC) were measured in sera from 97 patients with lupus erythematosus, including 66 with systemic lupus erythematosus (SLE), 12 with widespread discoid lupus erythematosus (W-DLE), 5 with subacute LE and 14 with localized DLE. We used a Clq enzyme immunoassay (Clq EIA) and an a-C3 enzyme immunoassay (a-C3 EIA). Elevated CIC levels were most frequently noted in cases of SLE, in both assays. However, we found no significant correlation between the results of Clq EIA and that of a-C3 EIA. In SLE patients, disease activity correlated with the results of Clq EIA but not with that of a-C3 EIA. CIC positive sera with both assays were detected only in cases of SLE and W-DLE and not in other types of LE. By gel filtration with Sephacryl S 300 superfine, it was possible to estimate the molecular size distribution of CIC. Several peaks of CIC varying from large (over the M.W. of IgM) to small size (near the M.W. of IgG) were found in each assay. Therefore, about one half of the peaks detected by Clq EIA showed different distributions of molecular size from that of a-C3 EIA. There was no significant differentiation of size distribution patterns among SLE, W-DLE, subacute LE and L-DLE. Distribution pattern of the molecular size was studied in sequential sera from two patients with active SLE before and after oral steroid therapy. The disappearance of large size CIC and decrease of total CIC levels were seen with this therapy.
