T-cell immunosenescence and inflammatory response in atomic bomb survivors.
In this paper we summarize the long-term effects of A-bomb radiation on the T-cell system and discuss the possible involvement of attenuated T-cell immunity in the disease development observed in A-bomb survivors. Our previous observations on such effects include impaired mitogen-dependent proliferation and IL-2 production, decreases in naive T-cell populations, and increased proportions of anergic and functionally weak memory CD4 T-cell subsets. In addition, we recently found a radiation dose-dependent increase in the percentages of CD25(+)/CD127(-) regulatory T cells in the CD4 T-cell population of the survivors. All these effects of radiation on T-cell immunity resemble effects of aging on the immune system, suggesting that ionizing radiation might direct the T-cell system toward a compromised phenotype and thereby might contribute to an enhanced immunosenescence. Furthermore, there are inverse, significant associations between plasma levels of inflammatory cytokines and the relative number of naïve CD4 T cells, also suggesting that the elevated levels of inflammatory markers found in A-bomb survivors can be ascribed in part to T-cell immunosenescence. We suggest that radiation-induced T-cell immunosenescence may result in activation of inflammatory responses and may be partly involved in the development of aging-associated and inflammation-related diseases frequently observed in A-bomb survivors.
Department of Radiobiology, Radiation Effects Research Foundation, Hiroshima, Japan. ykusunok@rerf.or.jp
Yoichiro
Y
Kusunoki
Mika
M
Yamaoka
Yoshiko
Y
Kubo
Tomonori
T
Hayashi
Fumiyoshi
F
Kasagi
Evan B
EB
Douple
Kei
K
Nakachi
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015496:CD4-Positive T-Lymphocytes / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D007249:Inflammation / Q000209:etiology*; D008297:Male; D009689:Nuclear Warfare; D017741:Survivors; D013601:T-Lymphocytes / Q000276:immunology / Q000528:radiation effects*; D050378:T-Lymphocytes, Regulatory / Q000528:radiation effects