Radiosensitivity of CD3−CD8+CD56+ NK cells

The effect of lower doses (0.5–3.0 Gy) of gamma radiation on radiosensitivity of CD3−/CD8+ NK cells subpopulation isolated from the peripheral blood of healthy volunteers was studied 48 h after the irradiation. Only a subtle increase in terms of induction of apoptosis (A+ cells), was observed in Annexin positive CD3−/CD8+ NK cells. The assessment of the relative presence of CD3−/CD8+ NK cells in Annexin negative populations of lymphocytes considerably contributes to the elimination of individual variability and could be useful in biodosimetry.Living CD3−/CD8+; Annexin negative NK cells were analyzed using five-color flow cytometry 16 h after irradiation by the doses of 1–10 Gy. The study was carried out on NK cells subsets CD3−/CD8− CD16+, CD56 (dim) and CD56 (bright). NK cells characterized with their low-density expression of CD56 (dim) are more cytotoxic and express CD16. Those with high-density expression of CD56 (bright) are known for their capacity to produce cytokines following activation of monocytes but their natural cytotoxicity is low; they are classified as CD16− or CD16 (dim). A dose-depending decrease in the relative presence of CD3−/CD8+ NK cells was observed 16 h after ionizing radiation (1–10 Gy). The decrease was highly pronounced in CD56 (bright) subset of NK cells and this subpopulation was considered as the most radiosensitive one. Unfortunately, the most radiosensitive subpopulation of NK cells – CD56bright cannot be used as a biodosimetric marker due to its insufficient amount in peripheral blood.