Fig. 4: Functions of T_SCM CD4 cells during aging.

a Proliferation profile of CD4 T-cell subsets during aging. Representative histogram of CFSE dilution from sorted T-cell subsets collected in young or older donors and stimulated with anti-CD3/CD28 microbeads or IL-7 (10 ng/ml) during 5 days. b Alteration of proliferative potential of T_SCM CD4 cells in response to TCR stimulation as measured in (a). T-cells subsets were freshly isolated from blood of young and older donors (n = 8 and 9, respectively). The statistical analysis was performed on unpaired samples (U Mann–Whitney test) (* for p < 0.05). Source data are provided as a Source Data file. c Decreased secretion of homeostatic and effector cytokines by T_SCM CD4 cells during aging. Sorted CD4 T-cell subsets were polyclonally stimulated with PMA/Ionomycin. The cytokines concentration was represented by an heatmap to visualize the acquisition of effector functions during differentiation and the specific signature associated with aging (n = 6 for young and old donors). Source data are provided as a Source Data file. d Increased engraftment of human T_SCM CD4 cells from aged donors in humanized NOD SCID gamma chain (NSG) mice. T_SCM CD4 cells from young (n = 2) or old donors (n = 2) were differentiated from T-naive precursors, expanded in vitro before their xenotransplantation into NSG mice (n = 13 and n = 9, respectively). At 21 (Exp#1) or 28 (Exp#2) days after the human T_SCM CD4 cells transfer, animals were killed and euthanized by CO₂, and tissues were collected (spleen, lungs). N = 2 independent experiments were performed and labeled by the color code on the graph (filled circles: Exp#1; open circles: Exp#2; filled gray circle represents the mouse with GVHD signs and killed at day 16). The statistical analysis was performed on unpaired samples (U Mann–Whitney test) (** for p < 0.01). e Reduced CDR3 diversity in naive CD4 T cells. Naive T-cell subsets were sorted as naive, T_RTE, T_MNP, and T_SCM CD4 cells. The extraction of mRNA was performed just after T-cell sorting, and analyzed by RNA-seq. CDR3 composition was compared between cell subsets and during aging. A connective arc represented high degree of homology (80%) between CDR3 sequences during differentiation and aging.