Clinical utility of assays for circulating immune complexes.

There are now many assays for the quantification of circulating immune complexes, each with distinct specificity and sensitivity. In a wide variety of rheumatic, infectious, neoplastic, and metabolic conditions, levels of circulating immune complexes may be elevated. In select situations, determination of circulating immune complex levels may help clinicians in the management of their patients. In lupus erythematosus, circulating immune complex levels, in conjunction with other immune parameters, may provide more insight into the disease course and activity than assessment of end organ parameters alone. In the differential diagnosis of infective endocarditis, serial levels of circulating immune complexes may provide evidence of effectiveness or failure of treatment. There is evidence that assays for circulating immune complexes may be of potential benefit in the management of Lyme disease and acute myelogenous leukemia.