Application of polyethylene glycol turbidity assay to detection of circulating immune complexes in cancer patients.

A rapid, reproducible immune complex screening assay was used to quantitate levels of circulating immune complexes in the sera of normal subjects, patients with documented increases in immune complexes from rheumatoid arthritis, patients with clinically or microbiologically documented infections, and patients with cancer. Although wide variations in individual values within the groups were noted and the concurrent elevation of polyethylene glycol-circulating immune complex levels by infection was documented as expected, significant differences were found in the values in patients with cancer compared with those in normal subjects. The overall clinical application of polyethylene glycol-circulating immune complex screening is discussed and current application of screening of serial sera samples from individual patients for correlation with measurable tumor volume is proposed.