Circulating immune complexes in the general hospital population and in patients who have renal disease. A preliminary evaluation of the platelet aggregation test for use in the hospital laboratory.

The platelet aggregation test was used to measure circulating immune complexes in patients who had glomerulonephritis and autoimmune disease, and in unselected hospitalized patients. Titers higher than those for the control group were found for groups with acute glomerulonephritis, Berger's disease, renal transplants, lupus nephritis, and polyarteritis nodosa. Hospitalized patients had titers that were higher than normal in more than one out of five cases. This preliminary study showed that the platelet aggregation test detects immune complexes in many conditions previously reported to give positive results with other assays. The test seemed suitable for use in most hospital laboratories, since it was simple, reliable, and inexpensive. The observation of detectable circulating immune complexes in 23% of the general hospital population suggests that this phenomenon may be more common than was previously suspected.