Assessment of the adaptive response induced by quercetin using the MNCB peripheral blood human lymphocytes assay

Over more than two decades the existence of an adaptive response (AR) has b een reported in several cell types and extensively studied with low doses o f radiation. Besides radiation, some chemicals [alkylating compounds, mitom ycin C (MMC), bleomycin, hydrogen peroxide and metals] may also induce an a daptive response. We have recently reported that the food mutagen quercetin can also induce an adaptive response in V79 Chinese hamster cells. In this work we have studied the effect of low doses of quercetin on the genotoxic ity of MMC and bleomycin assessed by the formation of micronuclei in cytoki nesis-blocked (MNCB) human peripheral blood lymphocytes. Our results sugges t the existence of an AR induced by quercetin in human lymphocytes. Seven o f the nine donors studied showed in at least one independent experiment a s ignificant decrease in the frequency of MNCB induced by MMC. The range of t hese decreases varied between 31 and 58%. In addition, we observed an AR in duced by quercetin towards challenging doses of bleomycin. In accordance wi th other studies with ionizing radiation in which heterogeneity of the AR i n the population has been extensively observed, the response here reported also showed some degree of variability between the different donors studied . In view of the results obtained one cannot rule out a possible protective effect of low doses of quercetin leading to adaptation to further exposure to mutagens or carcinogens.