FLOW CYTOMETRIC ANALYSIS OF MICRONUCLEI IN THE CD2+ - SUBPOPULATION OF HUMAN-LYMPHOCYTES ENRICHED BY MAGNETIC SEPARATION/

An improved flow cytometric method for the scoring of micronuclei in h uman lymphocytes irradiated in vitro is presented. Because, especially in cultivated human lymphocytes, unspecific DNA-containing debris fro m dying cells can influence the measured frequency of micronuclei, a p reselection of CD2 + population was performed before preparation of th e suspension of micronuclei and nuclei. Magnetic separation using anti -CD2 antibody-conjugated magnetic beads were used for this purpose. Th e results obtained by this improved flow cytometric technique were com pared with results obtained by microscopic scoring using the CB techni que. No correlation was found when the individual values in unirradiat ed controls were compared, due mainly to the presence of DNA-containin g particles from fragmented cell nuclei and other unspecific debris. T he averaged data from nine dose-effect curves simultaneously analysed by both techniques showed a linear-quadratic dose dependence with alph a and beta's that were similar for flow cytometry and for microscopic scoring. Only the constant term was higher for the flow cytometric res ults. A correlation between both techniques applied to individual data at doses >0.2 Gy could also be demonstrated. It is concluded that a d ose estimation of man exposed to low doses of ionizing radiation can a t present not be improved by the flow cytometric technique.