Use of bovine conglutinin for the assay of immune complexes.

We have used purified bovine conglutinin to develop a solid state radioimmune assay for immune complexes. Employing aggregated human IgG incubated with fresh normal human serum (complement) as a model for immune complexes, we have shown that our conglutinin assay is sensitive and highly specific for immune complexes that have fixed complement. The assay preferentially detects large complexes, is minimally influenced by monomeric IgG, and can be inhibited by high ionic strength, calcium chelation, and acetamido sugars. In addition, we have surveyed several hundred clinical sera from patients with various immunopathologic disorders and find evidence of immune complexes in some.