[Cellular immune defect caused by postoperative irradiation in patients with squamous epithelial carcinomas of the upper aerodigestive tract].

The effect of locoregional postoperative radiation therapy on cellular immunity was investigated in 11 patients with head and neck cancer. During the course of the radiation therapy, total lymphocyte counts, CD8+ lymphocyte counts and especially CD4+ lymphocyte counts decreased significantly. The mean CD4+ lymphocyte counts dropped from 739/microliters to 183/microliters (p < 0.001) and the average CD4+/CD8+ ratio also decreased significantly. In addition all patients showed impaired in vitro lymphocyte stimulation responses to several mitogens, with reductions found to be 10% to 50% of normal responses. Within 3-4 weeks after radiation therapy there was a slight increase of CD4+ lymphocyte counts and the in vitro lymphocyte stimulation responses showed a tendency to normalization. These results indicate that locoregional postoperative radiation therapy in patients with head and neck cancer can induce a severe impairment of cellular immunity.