Circulating immune complexes in patients with lung cancer.

Sera from 41 patients with lung cancer and 41 age and sex-matched hospital inpatients with non-malignant disease were tested for the presence of immune complexes using the 125Iodine Clq binding test. All patients were untreated or had recurrences after surgery. An increased Clq binding activity was found in 34% of patients with lung cancer and 24% of patients with non-malignant disease. There was no significant association between increased serum Clq binding activity and histological tumour type or survival but there was an association with the extent of malignant disease. No patient with limited (state 1) disease had raised Clq binding activity but in 42% of patients with extensive disease it was increased. Increased Clq binding activity did not correlate with either an increased total white cell count of ESR. Measurement of Clq binding activity may be of value in serial monitoring of disease progress and response to treatment.