Clinical correlates of circulating immune complex levels in advanced lung cancer. A discrimination analysis

Sera from 53 patients with unresectable lung cancer were tested for the presence of immune complexes by 12 assays. 5 assays (EA rosette inhibition, ADCC inhibition, platelet aggregation, IgG and C3 concentrations in PEG precipitates) could discriminate cancer patients from healthy subjects with over 80% reliability. On the basis of 3 assays (EA-I, ADCC-I and PEG-C3) a function allowing a 100% correct classification could be formulated:--(EA-I)--0.5 (ADCC-I) + 2.4 (PEG-C3) greater than 69.3, i.e., results higher than 69.3 are characteristic for cancer patients and lower than 69.3 for normal subjects. The relationship between the immune complex levels and the average survival time was not altered by sex, age, histology and treatment. None of the immune complex assays or their combination were useful for the estimation of individual life expectation.