Altered T-cell repertoire in aged naive mice.

<p>Contraction of the T-cell repertoire in aged naive mice: 3 and 18mths naive B6 mice were sacrificed and splenocytes stained for CD4⁺T-cell subpopulations (n = 6). CD4⁺T-cells were reduced in frequency and total numbers in older animals (<b>A</b>). Effector/memory CD4⁺T-cells and early activated CD4⁺T-cells accumulated in older animals while frequencies of regulatory T-cells were age-independent (<b>B</b>).