Detection of circulating immune complexes in patients with squamous cell carcinoma of the oral cavity

Circulating immune complexes (CICs) have been quantitated from the sera of untreated oral cancer patients and those treated with radiation or surgery using C1q binding assay in terms of percent binding activity (C1q BA) and microgram/ml equivalent of aggregated human gamma globulin (AHG). Sera from a total of 108 oral cancer patients and 47 normal healthy donors were evaluated for CICs. Out of these, 48 patients were tested before treatment and 60 were tested 6 months to 1 yr after treatment. Levels of CICs were elevated in 70.8% patients before treatment (mean % C1q BA 29.6 +/- 2.2) when compared to healthy controls (4.2% positive, mean % C1q BA 9.0 +/- 0.8). Treated patients showing no evidence of the disease had reduced CIC levels, only 11.7% patients showing C1q BA at the level of 13.2 +/- 1.4. On the other hand, treated patients showing recurrence of the disease had much higher CIC levels (mean % C1q BA 42.8 +/- 3.5, 92.3% positive) even higher than the untreated patients. Status of CIC levels as well as recurrence rate in patients treated with either radiation or surgery were comparable. One out of 4 individuals with premalignant changes such as oral leukoplakia showed elevated levels of CICs.