Radiosensitivity of CD45RO + Memory and CD45RO - Naive T Cells in Culture

Abstract

Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4+ helper and CD8+ killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO+ memory and CD45RO- naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO+ cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity.

Detection of apoptotic frequency in Chinese hamster ovary (CHO-K1) cells after gamma-irradiation using both neutral Comet assay andterminal desoxynucleotidyl transferase (TdT) assay

“…In such a case, the fluorescent density of the comet became too dim to be recognized (8,14). As a result of that, apoptotic frequencies detected at 72 h by Comet assay are lower than those at 48 h, whereas apoptotic frequencies detected at 72 h by TdT assay are much higher than the frequencies at 48 h. Our results were in accordance with some others (13,15). The results indicated that the Comet assay is suitable for apoptotic detection at an early stage.…”

Short‐term culture and γH2AX flow cytometry determine differences in individual radiosensitivity in human peripheral T lymphocytes

“…Moreover, the cultured T-lymphocyte populations used in the present study for individual radiation sensitivity appeared to be mainly composed of memory Tlymphocytes, with more than half memory CD8 T-lymphocytes. It has been reported that memory T-lymphocytes are more radiation-sensitive than naïve T lymphocytes [Uzawa et al, 1994]. Therefore, it is possible that excessive proliferation of memory CD8 T-lymphocytes in the culture might affect the individual radiosensitivity difference that we detected with gH2AX-FCM.…”

Selective Changes in the Immune Profile of Tumor-Draining Lymph Nodes After Different Neoadjuvant Chemoradiation Regimens for Locally Advanced Cervical Cancer

“…Both LD and HD radiation reduced the frequency of naïve-type CD4 + and CD8 + cells, which are scarcely effective in the context of the antitumor response, thereby suggesting a similar beneficial effect on the TDLN immune state. This phenomenon, however, might merely reflect the direct detrimental activity of radiation on naïve T cells, typically highly sensitive to radiation (29).…”