The influences of age on T lymphocyte subsets in C57BL/6 mice.

The aim of this study is to evaluate the age related changes of T lymphocyte subsets in C57BL/6 mice and immune function. Multi-color immunofluorescence techniques that were used to analyse relative numbers of T lymphocyte subsets include CD4, CD8, naive and memory CD4 and CD8, CD8CD28 T cells in peripheral blood of C57BL/6 mice from different age groups (Group I: 2 months old; Group II: 7 months old; Group III: 21 months old); Splenocytes isolated from different group mice were stimulated with Con A to evaluate the proliferative ability. Compared with group I, group II had a significant reduction in the percentage of CD4, naive CD4 and CD8 T cells and an increase in the percentage of CD8 T cells, while group III had a significant reduction in the percentage of CD4, naive CD4 and CD8 T cells and increase in the percentage of CD8, memory CD4 and CD8 T cells in peripheral blood. Compared with group II, group III had a significant reduction in the percentage of naive CD8 T cells and increase in the percentage of memory CD4 and CD8, CD8CD28 T cells in peripheral blood. The T lymphocyte proliferation in vitro showed that groups II and III had a lower proliferative capacity than group I, between groups II and III, there was not a significant difference. We provide relative values for the T lymphocyte subsets in the different age groups of C57BL/6 mice. The immune system began aging at 7 months old in C57BL/6 mice under a specific pathogen free environment.