Expression of blood group H antigen type 2 chain by oral carcinoma cells after radiotherapy

The blood group H antigen type 2 was investigated immunohistochemically in sections of 44 surgical specimens from the oral mucosa. These comprised 35 squamous cell carcinomas obtained from 22 patients and 9 specimens of clinically healthy mucosa. The carcinoma specimens included 10 primary lesions and 25 recurrent lesions from patients who had undergone radiotherapy. The results showed that the specimens of normal oral mucosa stained at higher antibody titers than either group of carcinomas, and that postradiation recurrent tumors stained at higher titers than primary tumors. In 10 patients, both preradiation and postradiation carcinomas were examined; the postradiation lesions showed increased reactivity in 5 patients, no change in 3 patients, and a decrease in antigen reactivity in 2 patients. The expression of antigen H type 2 in the recurrent tumors appeared to correlate with the estimated daily tumor radiation dose; tumors with specific antigen staining took twice as long to recur after radiotherapy than tumors without similar staining. The results suggest that the expression of the blood group H antigen type 2 substance, being a differentiation antigen, is enhanced by the effect of radiation on the malignant cell.