Induction of micronuclei and apoptosis in natural killer cells compared to T lymphocytes after gamma -irradiation

Abstract

Purpose: To investigate the chromosomal damage caused by gamma irradiation in T lymphocytes and natural killer (NK) cells and compare this with apoptosis induction in both lymphocyte subsets. Materials and methods: Apoptosis induction by gamma -irradiation in T lymphocytes and NK cells was quantified using the annexin V flow cytometric assay. The cytokinesis-block micronucleus (MN) assay was used to evaluate the induced 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 cytometer and the number of MN in the sorted binuclear cells was scored. Doses of 1 and 2 Gy gamma -irradiation were applied. Results: Higher numbers of MN in NK cells were found compared with the MN yield in T lymphocytes. In contrast, NK cells were less than T lymphocytes prone to apoptosis after gamma -irradiation. Conclusion: The results support the view that cytogenetic damage and apoptosis after gamma -irradiation are not necessarily correlated.