The Effect of Chronic Radiation on the Humoral Immune Response of Rainbow Trout (Onchorhynchus Mykiss Walbaum)

Abstract

Two separate experiments have examined the effect of exposing rainbow trout to chronic γ-radiation, commencing immediately after fertilization. In experiment 1 the period of exposure extended for 20 days with groups receiving mean dose rates of 1·87, 3·73 and 9·03 mGy h⁻¹, and mean total accumulated doses of 0·83, 1·66 and 4·01 Gy respectively. At 5 months of age fish were tested for specific antibody response to dinitrophenol coupled to keyhole limpet haemocyanin (DNP-KLH) and there was no significant difference in titre between irradiated groups and unirradiated controls. In experiment 2 the exposure period was extended to 246 days from fertilization. Mean dose-rates to the three groups used were the same as in the first experiment until hatching at 21 days and then lower with rates of 0·99, 1·9, and 4·66 mGy h⁻¹ to the free-swimming fish. The mean total accumulated doses over the whole irradiation period were 5·43, 10·53 and 25·43 Gy respectively. The antibody response to DNP-KLH was significantly lower in trout receiving the highest dose-rate when compared with those of unirradiated controls or the lowest dose-rate group. The significance of these results is discussed in relation to radiation levels in areas of radioactive waste disposal, and results from a similar study published previously.