[Comparative studies on immunomodulation via hyperfractionated whole-body irradiation].

The effect of the humoral immune response on Sprague-Dawley rats by hyperfractionated total body irradiation was investigated. These experiments included single doses of total body irradiation (1 Gy, 2 Gy, 3 Gy) and the administration of 1 Gy and 2 Gy in two or three fractions 2 x 0.5 Gy, 3 x 0.33 Gy and 2 x 1.0 Gy, 3 x 0.66 Gy. The time between the fractions was six hours. The primary production of antibodies against erythrocytes of sheep were determined as immunity parameter. The immune stimulation could be achieved, when single doses of 1 or 2 Gy were delivered. The single dose of 3 Gy total body irradiation showed a small, not significant immunosuppression. A significant immunosuppression was observed in all our hyperfractionated experiments. The degree of immunosuppression was nearly equivalent in the hyperfractionated group (2 x 0.5, 3 x 0.33 Gy and 2 x 1.0, 3 x 0.66 Gy).