The elderly accumulate GrB⁺CD8⁺ T cells and 4-1BBL⁺ B cells. (A-B) Proportions of CD28^Low/- (i) and GrB⁺-expressing CD8⁺ T cells (ii) and for 4-1BBL⁺ B cells (B) are increased in the elderly (Old, n = 28), compared with the young (Young, n = 18). Shown are CD28 (i, a representative histogram) and GrB (ii, mean ± SEM) expressions in gated PB CD8⁺ T cells, and a representative dot plot (%; B, upper panel) and a summary whiskers-and-box plot (Student t test P = .009, Mann-Whitney U test P = .008, Kolmogorov-Smirnov test P = .003; B, lower panel) of 4-1BBL in gated CD19⁺ B cells. (C) The 4-1BBL⁺ B cells in old human donors (black line) also are CD27⁺ CD40⁺ CD86^High HLA-I^High but HLA-DR^Low, compared with the 4-1BBL^– B cells (dotted line). (D-F) 4-1BBL⁺CD19⁺ B cells were enriched in some patients with inflammatory breast cancer after auto-HSCT (n = 11, D). 4-1BBL⁺ CD19⁺ B cells (gated in CD19⁺ cells, D) were enriched above the 6% level of arbitrary threshold set for healthy donors. The samples were also enriched for GrB⁺CD28^LowCD8⁺ T cells (mean ± SEM [E-F]). *P < .05 was considered significant.