Effects of ACNU and cranial irradiation on the mouse immune system

The effects of ACNU and cranial irradiation on the immune system were studied in three groups of 90 mice: Group A, intraperitoneal injection of ACNU (30 mg/kg); Group B, single exposure of 10 Gy to the head; and Group C, intraperitoneal injection of ACNU (30 mg/kg) and single exposure of 10 Gy to the head. Peripheral white blood cell counts, spleen cell subsets, natural killer (NK) cell activity, lymphocyte blastogenesis, and production of interferon (IFN)-gamma were analyzed once a week for 6 weeks after treatment. In Group A, NK cell activity decreased between weeks 4-5, concanavalin A blastogenesis decreased during weeks 1-5, and the levels of L3T4 (CD4) and Lyt2 cells (CD8) and IFN-gamma production decreased during weeks 2-5. However, all tested parameters returned to the normal range at 6 weeks. In Group B, all parameters except for the L3T4 cell level and the IFN-gamma production decreased during week 1, and returned to the normal range thereafter. The concentration of L3T4 cells decreased during week 2 and between weeks 5-6. The IFN-gamma production increased during week 1, decreased during week 2, and returned to the normal range thereafter. In Group C, the suppressive effects were severe and continued for a longer period than in either Group A or B. Concanavalin A blastogenesis, L3T4 cell concentration, and IFN-gamma production were still suppressed after 6 weeks. Therefore, intensive radiochemotherapy for brain tumor may suppress the immunological function.