Absence of Correlations between Radiosensitivities of Human T-Lymphocytes in G₀ and Skin Fibroblasts in Log Phase Available to Purchase

Dose-survival curves were obtained for matched samples of peripheral T-lymphocytes and skin fibroblasts from a total of 22 patients who underwent various surgical procedures using loss of colony-forming ability as the end point. The results showed that the mean|$D_{10}$| (dose required to kill 90% of cells) ± SD was 3.58 ± 0.21 Gy for T-lymphocytes irradiated in G₀ and 3.19 ± 0.37 Gy for skin fibroblasts irradiated in log phase. The coefficients of variation were found to be 6 and 11%, respectively. Contrary to the expectation, regression analysis of|$D_{10}$| values for the two types of cells revealed no significant correlations. The absence of correlation most probably derives from the fact that the apparent interindividual variability of dose-survival curves is caused primarily by random experimental fluctuations at least in the case of lymphocytes. Possible reasons for the greater variability observed in the fibroblast assay are discussed.