Abstract
[Purpose] We have reported that human memory CD4 T cells in peripheral blood can be discriminated into three functionally different subsets (M1-3) by using HSCA-2 mAb against CD43 (J.Immunol,169:39,2002, J.Immunol,172: 7246,2004). The M1 subset consists of functionally maturated cells whose CD43 expression is relatively high; the M2 subset cells that express moderate levels of CD43 and respond weakly to TCR-mediated stimuli; and the M3 subset cells whose CD43 expression levels are relatively low and which are anergic to TCR-mediated stimuli and prone to spontaneous apoptosis. To evaluate how properly T-cell memory is maintained in A-bomb survivors, in this study we examined the relationship between the proportion of these memory CD4 T-cell subsets and aging or radiation exposure.
[Results and Discussion] The percentage of each memory T-cell subset in the CD4 T-cell population appeared to significantly increase with age but did not differ between males and females. It was also suggested that there were dose-dependent increases in the percentages of M2 (P = 0.036) and M3 (P = 0.059) subsets. Generally, individual ability to properly maintain T-cell memory is known to decline with aging. It is conceivable that the present study provided support to the hypothesis that such immunological aging has been accelerated in A-bomb survivors.
