Microarray analysis reveals similarity between CD8CD28 T cells from young and elderly persons, but not of CD8CD28 T cells

We isolated highly purified CD8CD28 and CD8CD28 T cell populations from healthy young and elderly persons for gene expression profiling using Affymetrix oligonucleotide microarrays. We demonstrate that the gene expression profile of CD8CD28 T cells is very similar in young and elderly persons. In contrast, CD8CD28 in elderly differ from CD8CD28 in young persons. Hierarchical clustering revealed that CD8CD28 in elderly are located between CD8CD28 in young and CD8CD28 (young and old) T cells regarding their differentiation state. Our study demonstrates a dichotomy of gene expression levels between CD8CD28 T cells in young and elderly persons but a similarity between CD8CD28 T cells in young and elderly persons. As CD8CD28 T cells from elderly and young persons are distinct due to a different composition of the population, these results suggest that the gene expression profile does not depend on chronological age but depends on the differentiation state of the individual cell types.