The L1210 assay for immune complexes: Application in cancer patients and correlation with disease progress

Immune complexes (ICs) were determined by the non‐complement‐dependent L1210 radioimmune assay on 132 serum samples collected from 53 patients with a variety of cancers. Both the mean IC levels and frequency of positive tests were significantly greater in cancer patients (mean = 96±100 μg/ml, 46% positive) than in a control group of 67 normal healthy blood donors (mean = 39±15, 3% positive). When cancer patients were assorted into groups by disease progress, those with large or progressing tumors had significantly higher mean values (136±129) and frequency of positives (75%) than those with small or regressing tumors (58±18, 22% positive). In lung cancer patients, IC levels showed a strong inverse correlation (r s = −0.903) with survival time in patients who died, and appeared to be a better prognostic indicator than performance status (Karnofsky scale) at time of diagnosis. Serial IC measurements taken on several patients showed a decrease in levels concomitant with a favorable response to cytoreductive therapy, sustained normal levels during periods of prolonged remission, and a rise to elevated levels with (and sometimes preceding) documentation of new metastases.