Circulating immune complexes in patients with bone tumours.

Sera from 62 patients with osteogenic sarcoma and 12 with malignant giant-cell tumour were tested for the presence of immune complexes by the 125I-Clq binding assay. Elevated serum Clq binding activity was found in 67.7% of the osteogenic sarcoma patients and in 75% of the giant-cell tumour patients. These results were compared with those obtained with five sera from patients with benign bone tumours and 20 sera from normal young donors. In the last two groups, the incidence of elevated Clq-binding activity was 0% and 5%, respectively. In some patients with giant-cell tumours, pre- and post-operative serum samples were studied, showing a decrease in test values after tumour resection. Preliminary sequential studies of individual patients indicate that the 125I-Clq binding assay may be useful for monitoring patients with bone tumours.