Chronic low-dose gamma-radiation exposure and the alteration of the distribution of lymphocyte subpopulations in residents of radioactive buildings

Purpose: To elucidate the immunological change incurred in a human populati on by protracted gamma-radiation exposure at home environment. Materials and methods: An examination on the CD3(+), CD4(+) CD8(+) and HLA- DR+ lymphocyte subsets was arranged for 196 exposed subjects with mean exce ss cumulative dose of 169 mSv during 2-13 years of exposure. Another 55 clo se relatives of the exposed subjects were recruited as the non-exposed refe rence population Results: The mean percentages of CD4+ T-lymphocytes, HLA-DR+ lymphocytes an d the CD4(+)/CD8(+) ratios in the exposed subjects (35.5, 19.9 and 1.51 res pectively) were significantly lower than those of reference individuals (38 .0, 22.6 and 1.72; p = 0.02, 0.003, and 0.03 respectively), while the CD8() in total counts of the exposed was moderately increased above that of the reference populations (P=0.1). By ANOVA analysis, the percentages of CD4() and HLA-DR+ subsets were significantly associated with radiation dose (p= 0.0046, 0.003), while CD4(+)/CD8(+) ratios were moderately associated with dose (p=0.073). HLA-DR+ counts were significantly and positively associated with duration of relocation from radioactive apartments (p=0.029). Conclusions: Significant immunological effects were observed in those who h ad received chronic low-dose radiation exposure.