Callahan J E, Kappler J W, Marrack P
Department of Biochemistry, University of Colorado, Denver 80262.
J Immunol. 1993 Dec 15;151(12):6657-69.
As mice age, spontaneous changes occur in the receptor repertoire of their T cells. The receptor repertoire of CD4+ T cells does not change with age. By contrast, however, the percentage of alpha beta+, CD8+ T cells bearing particular V elements varies considerably between individual aged mice, although it is remarkably consistent among individual young animals within a given strain. Changes of receptor V element use among CD8+ T cells in individual mice are unpredictable. However, when a large number of mice of the same strain is analyzed, strain-specific trends in V element skewing are found. Old C3H.SW and B10.BR mice have mono- or oligoclonal expansions of CD8+ T cells. These expansions of peripheral CD8+ T cells with age are probably due to deregulation of proliferation of individual CD8+ T cells after recognition of viral or environmental Ag, accompanied, perhaps, by partial transformation of particular T cell clones. Another phenomenon documented herein is the fact that the CD4/CD8 ratio drops steadily as a function of age. Shifts in CD4/CD8 ratio were not due to increased numbers of CD8+ T cells in spleen and lymph nodes, rather the CD4+ T cells disappeared from aging mice faster than CD8+ T cells.
随着小鼠年龄增长，其T细胞受体库会发生自发变化。CD4+ T细胞的受体库不会随年龄改变。然而，相比之下，携带特定V基因片段的αβ+、CD8+ T细胞的百分比在老年个体小鼠之间差异很大，尽管在给定品系的年轻个体动物中该比例非常一致。个体小鼠CD8+ T细胞中受体V基因片段使用的变化是不可预测的。然而，当分析同一品系的大量小鼠时，会发现V基因片段偏向性的品系特异性趋势。老年C3H.SW和B10.BR小鼠有CD8+ T细胞的单克隆或寡克隆扩增。外周CD8+ T细胞随年龄的这些扩增可能是由于单个CD8+ T细胞在识别病毒或环境抗原后增殖失控，可能还伴有特定T细胞克隆的部分转化。本文记录的另一个现象是CD4/CD8比值会随着年龄增长而稳步下降。CD4/CD8比值的变化并非由于脾脏和淋巴结中CD8+ T细胞数量增加，而是CD4+ T细胞从衰老小鼠中消失的速度比CD8+ T细胞更快。
