Immunocomplexes and primary lung cancer

Circulating immune complexes (CIC) were found in 47% of 71 patients before treatment, in a horizontal study of the presence of CIC in primary lung cancer (PLC). The precipitation technique in PEG was used, and C1q, IgG and IgM fractions in the precipitate were assayed. Especially in epidermoid carcinoma, CIC were found in 1/6 cases with stage 1, 2/9 with stage II and 21/34 with stage III. The frequency was significantly higher in stage III cases, and showed a significant tendency to increase with progression of the clinical stage. If stage parameters are considered separately, this tendency correlates significantly (p less than 0.002) with the amount of lymph node involvement (N) but not to the tumor (T) size nor to the presence of metastases (M). Analysis of CIC behavior in comparison with the single fractions showed that C1q and/or IgG were elevated in 40% of cases. The presence of C1q and/or IgG associated with IgM is more characteristic of stage N2, while the presence of CIC with the fractions C1q and/or IgG not associated with IgM is more frequent in stage N1. There was a lower survival rate at 12 months in patients with CIC as compared to those without (p less than 0.05).