Figure 4

CD4 and CD8 T cell absolute numbers increased during ageing in gut associated lymphoid tissues. (A) Gating strategy to identify CD4 and CD8 T cells. Dot plots shows cells isolated from small intestine lamina propria of a 23 months old C57BL/6 mouse. CD45 expressing cells were first selected, then lymphocytes gate was determined to finally discriminate TCRβ+ CD4+ cells and TCRβ+ CD8α+ cells. (B) Graphs show total CD4 (left) and CD8 (right) T cell numbers recovered from Peyer’s patches (PP), small intestine lamina propria (siLP) and colonic lamina propria (cLP) during ageing. Numeration and FACS analysis were performed on PP, siLP and cLP from young (Y) (n = 20), middle-aged (M) (n = 15) and old (O) (n = 10) C57BL/6 mice. Cumulative results show the mean ± SEM of absolute numbers recovered from independent experiment comparing young, middle-aged and/or old animals. Statistical significance (Student’s t test) is shown: ns, non-significant; *, p < 0.05; **, p < 0.01; ***, p < 0.001. (C) Association between mucosal CD4 T cell numbers (PP, siLP and cLP respectively) and secondary lymphoid organs (pooled mesenteric, axillary, brachial and inguinal lymph nodes and spleen) CD4 T cell numbers was evaluated using Spearman test. Spearman r and p value are indicated in each graph.