Fig. 4.

Immunoprecipitation of cC1qR/CaR by purified IgG from SLE. cC1qR/CaR was conjugated to biotin and incubated with purified IgG from SLE serum or normal donor (ND) serum. Alternatively, SLE IgG that was preincubated with increasing amounts of purified cC1qR/CaR was added to cC1qR/CaR-Bio and incubated. After precipitation using Prot G, the precipitate was electrophoresed on a polyacrylamide gel and blotted on PVDF membranes. CC1qR/CaR-Bio was demonstrated by subsequent incubation with streptavidin–horseradish peroxidase (HRP) and DAB.