The radiotoxicity of 131I therapy of thyroid cancer:: Assessment by micronucleus assay of B lymphocytes

We investigated cytologic radiation damage in thyroid cancer after I-131 therapy using micronucleus assay (MNA) of B lymphocytes exclusively, as opposed to our previous study in which MNA of all lymphocyte subsets was used. Methods: We studied 22 thyroid cancer patients treated with 3.7 GBq of I-131. Peripheral lymphocytes were harvested, and B lymphocytes were isolated by an immunomagnetic method and assayed for the frequency of micronuclei. Results: The frequency of micronuclei among B cells after I-131 therapy was significantly increased relative to that in untreated control subjects, and the I-131-induced increase in micronuclei frequency among B cells was significantly greater than that among all lymphocytes. Conclusion: Compared with the MNA of all lymphocytes, the MNA among specifically B cells may more sensitively detect cytologic radiation damage associated with I-131 therapy of thyroid cancer.