Decreases in percentages of naïve CD4 and CD8 T cells and increases in percentages of memory CD8 T-cell subsets in the peripheral blood lymphocyte populations of A-bomb survivors.
Our previous studies have revealed a clear dose-dependent decrease in the percentage of naïve CD4 T cells that are phenotypically CD45RA+ in PBL among A-bomb survivors. However, whether there is a similar radiation effect on CD8 T cells has remained undetermined because of the unreliability of CD45 isoforms as markers of naïve and memory subsets among the CD8 T-cell population. In the present study, we used double labeling with CD45RO and CD62L for reliable identification of naïve and memory cell subsets in both CD4 and CD8 T-cell populations among 533 Hiroshima A-bomb survivors. Statistically significant dose-dependent decreases in the percentages of CD45RO-/CD62L+ naïve cells were found in the CD8 T-cell population as well as in the CD4 T-cell population. Furthermore, the percentages of CD45RO+/CD62L+ and CD45RO+/CD62L- memory T cells were found to increase significantly with increasing radiation dose in the CD8 T-cell population but not in the CD4 T-cell population. These results suggest that the prior A-bomb exposure has induced long-lasting deficits in both naïve CD4 and CD8 T- cell populations along with increased proportions of these particular subsets of the memory CD8 T-cell population.
Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
Mika
M
Yamaoka
Yoichiro
Y
Kusunoki
Fumiyoshi
F
Kasagi
Tomonori
T
Hayashi
Kei
K
Nakachi
Seishi
S
Kyoizumi
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D018791:CD4 Lymphocyte Count / Q000379:methods; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology* / Q000528:radiation effects*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology* / Q000528:radiation effects*; D002454:Cell Differentiation / Q000276:immunology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007156:Immunologic Memory / Q000528:radiation effects; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000473:pathology* / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D009689:Nuclear Warfare; D011829:Radiation Dosage; D012737:Sex Factors; D017741:Survivors