T-cell immunosenescence and inflammatory response in atomic bomb survivors

• Published in: Radiation research Vol. 174; no. 6; p. 870
• Main Authors: Kusunoki, Yoichiro, Yamaoka, Mika, Kubo, Yoshiko, Hayashi, Tomonori, Kasagi, Fumiyoshi, Douple, Evan B, Nakachi, Kei
• Format: Journal Article
• Language: English
• Published: United States 01.12.2010
• Subjects: Aged; Aged, 80 and over; Aging; CD4-Positive T-Lymphocytes - radiation effects; Dose-Response Relationship, Radiation; Female; Humans; Immunologic Memory; Inflammation - etiology; Male; Nuclear Warfare; Survivors; T-Lymphocytes - immunology; T-Lymphocytes - radiation effects; T-Lymphocytes, Regulatory - radiation effects
• ISSN: 1938-5404
• DOI: 10.1667/RR1847.1

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.