Wilkins R C, Kutzner B C, Truong M, McLean J R N
Health Canada, Consumer and Clinical Radiation Protection Bureau, 775 Brookfield Road, Postal Locator 6303B, Ottawa, Ontario, K1A 1C1, Canada.
Int J Radiat Biol. 2002 Aug;78(8):681-8. doi: 10.1080/09553000210144475.
Apoptosis occurs spontaneously in cultured human peripheral blood lymphocytes but is enhanced by exposure to ionizing radiation. Subpopulations of lymphocytes are known to have varying radiosensitivities to radiation-induced apoptosis. The purpose of this study was to examine the radiation-induced apoptotic response of CD4(+) and CD8(+) T-cells incubated as a complete lymphocyte population.
Using a four-colour flow-cytometry method, which measures annexin-V binding to phosphatidyl serine and propidium iodide, spontaneous and radiation-induced apoptosis was measured in the total lymphocyte fraction and in CD4(+) and CD8(+) T-cell subpopulations.
It was found that CD8(+) T-cells were more sensitive to radiation-induced apoptosis than CD4(+) T-cells at doses up to 2 Gy. The yield of radiation-induced apoptosis in the total lymphocyte fraction decreased with increasing ratios of CD4(+) to CD8(+) T-cells (CD4/CD8 ratio). By manipulating the CD4/CD8 ratio within lymphocyte cultures, it was found that the CD4/CD8 ratio had a dramatic effect on the yield of spontaneous apoptosis of total lymphocytes fraction and CD4(+) T-cells but not CD8(+) T-cells.
The CD4/CD8 ratio affects the apoptotic response of human lymphocytes and CD4(+) T-cells.
凋亡在培养的人外周血淋巴细胞中自发发生，但暴露于电离辐射会增强凋亡。已知淋巴细胞亚群对辐射诱导的凋亡具有不同的放射敏感性。本研究的目的是检测作为完整淋巴细胞群体培养的CD4(+)和CD8(+) T细胞的辐射诱导凋亡反应。
使用一种四色流式细胞术方法，该方法测量膜联蛋白-V与磷脂酰丝氨酸和碘化丙啶的结合，在总淋巴细胞部分以及CD4(+)和CD8(+) T细胞亚群中测量自发和辐射诱导的凋亡。
发现在高达2 Gy的剂量下，CD8(+) T细胞比CD4(+) T细胞对辐射诱导的凋亡更敏感。总淋巴细胞部分中辐射诱导凋亡的发生率随着CD4(+)与CD8(+) T细胞比例（CD4/CD8比例）的增加而降低。通过在淋巴细胞培养物中操纵CD4/CD8比例，发现CD4/CD8比例对总淋巴细胞部分和CD4(+) T细胞的自发凋亡发生率有显著影响，但对CD8(+) T细胞没有影响。
CD4/CD8比例影响人淋巴细胞和CD4(+) T细胞的凋亡反应。
