BOVINE AND RABBIT LYMPHOCYTES CONDITIONED WITH HYDROGEN-PEROXIDE SHOWAN ADAPTIVE RESPONSE TO RADIATION-DAMAGE

We have carried out experiments to study the possible induction of an adaptive response in cultured bovine and rabbit lymphocytes conditione d with subtoxic doses of hydrogen peroxide after stimulation and subse quently challenged with 1 Gy of X-rays. Peroxide treatment was given a t different doses 48 h after the addition of PHA to stimulate the cell s. A protective effect of pre-exposure to H2O2 against radiation damag e detected as micronuclei in binucleated cells was evident for all the animals tested regardless the dose of H2O2 used, although this effect was in general of greater magnitude in bovine than in rabbit cells. T hese results lend further support to our previous finding in human lym phocytes that DNA single strand breaks induced by H2O2 (most likely du e to the generation of hydroxyl radicals) is the most important lesion to trigger the adaptive response.