Detection of circulating immune complexes in cutaneous disease using a monoclonal rheumatoid factor hemagglutination method.

A monoclonal rheumatoid factor (mRF) hemagglutination (HA) assay for the detection of circulating immune complexes is described. In this assay, human red blood cells coated with mRF were reacted in microtiter and, in the presence of circulating immune complexes, were agglutinated. Titers were determined and results were compared to a mRF inhibition (solid phase) radioassay (mRF-Inh). Serum samples [141] from patients with a variety of cutaneous diseases [78], systemic lupus erythematosus [19], rheumatoid arthritis [21] and normals [23] were tested by both methods. Eighty-four samples were positive by mRF-Inh and 75 mRF-HA. Seventy of the serum samples were positive by both methods for an overall correlation of 87%. When sucrose density gradient fractions were tested by both methods, results obtained by mRF-HA correlated with those obtained by mRF-Ihh in all patients studied. This procedure may be adapted for routine laboratory use and thus circumvents the need for costly equipment and hazardous radioactive materials.