Effect of X-Rays on Immunity: A Review

Unequivocal evidence of effects of X-irradiation on immunity is found in animals irradiated shortly prior to immunization with nonliving antigens. Irradiation before immunization eliminates direct ionizing effects on the antigen, and nonliving antigens eliminate such factors as invasiveness and continuing immunization from antigen multiplication. Nevertheless, work of great importance has been done on infections. This work, however, has to be interpreted with due regard to the fact that immunity of the host and virulence of the parasite, as the terms are used in this review, are measured to a large extent in terms of each other and are more or less reciprocal: In terms of this relationship, a faster recovery from infection by a host or a smaller parasite population in an irradiated host, as compared to untreated controls, may be the result of (1) an increased immunity of the host or (2) injury to the parasite so that its virulence is lowered.