| Abstract: | The recent association of alterations in T-lymphocyte subpopulations and impaired cellular immunity prompted an investigation of the effects of radiotherapy (RT) on serial levels of lymphocyte subsets in 30 patients with head and neck squamous carcinoma. Percentage and absolute levels of T3, T4, T6, T8, T10, T11, and Leu 7 cells were measured before, during, and after RT at monthly intervals for six months and compared with levels in 40 normal subjects. Sixteen patients received curative and 14 postoperative adjuvant RT. Before treatment, mean subset levels were similar among the patient and normal groups except for elevated Leu 7 (natural killer) cells in patients with stage I and II disease. There were profound decreases in absolute levels of each subpopulation during and after RT. The percentage of T4 (helper/inducer) cells decreased, whereas that of T8 (cytotoxic/suppressor) and Leu 7 cells tended to increase. Compared with normal values, the mean T4/T8 ratio decreased significantly by six months after RT, when absolute levels of the subsets had rebounded to pretreatment levels in the definitive RT group but remained profoundly decreased in the adjuvant group. The differing recovery patterns suggest that factors other than RT may contribute to persistent immunosuppression following RT. |
