INDUCTION OF MICRONUCLEI AND APOPTOSIS IN NATURAL-KILLER-CELLS COMPARED TO T-LYMPHOCYTES AFTER GAMMA-IRRADIATION

Purpose: To investigate the chromosomal damage caused by gamma-irradia tion in T lymphocytes and natural killer (NK) cells and compare this w ith apoptosis induction in both lymphocyte subsets. Materials and meth ods: Apoptosis induction by gamma-irradiation in T lymphocytes and NK cells was quantified using the annexin V flow cytometric assay. The cy tokinesis-block micronucleus (MN) assay was used to evaluate the induc ed cytogenetic damage. For the MN assays on NK cells, gamma-irradiated peripheral blood mononuclear cells were cultured and stimulated with interleukin 15 (IL-15). Afterwards the NK cells (characterized by the CD3(-)/CD56(+) phenotype) were separated with the FACSort flow cytomet er and the number of MN in the sorted binuclear cells was scored. Dose s of 1 and 2 Gy gamma-irradiation were applied. Results: Higher number s of MN in NK cells were found compared with the MN yield in T lymphoc ytes. In contrast, NK cells were less than T lymphocytes prone to apop tosis after gamma-irradiation. Conclusion: The results support the vie w that cytogenetic damage and apoptosis after gamma-irradiation are no t necessarily correlated.