Circulating IgA immune complexes in AIDS.

Circulating immune complexes were isolated from the serum of patients with AIDS, as well as patients with other acute and chronic viral diseases. Analysis of these immune complexes by methods of flow cytometry and by radioimmune (Raji cell) assay revealed a prevalence of IgA complexes in the serum of AIDS patients and a prevalence of IgG complexes in the serum of patients with other viral diseases. Raji cells bind immune complexes via Fc and complement (C3) receptors and may detect IgA immune complexes more efficiently than a C1q assay since IgA has no affinity for C1q.