State of T cells from CD28 deficient scurfy mice. (A) Lifespan of scurfy (sf), CD28 heterozygous scurfy [sf/CD28(+/−)], and CD28-deficient scurfy [sf/CD28(−/−)] mice (P < .001). (B) Total number of live cells present in inguinal lymph nodes (left panel) and subpopulations of lymph node cells (right panel). CD4+ cells: □, CD8+ cells: ▒, B220+ cells: ■, (mean ± SD, n = 3). (C) CD4/CD8 phenotypes of lymph node cells (top row) and thymocytes (bottom row). Cells from 25-day-old C57BL/6 (WT), CD28-deficient scurfy [CD28(−/−) scurfy], and cd28+/+scurfy (scurfy) mice were stained for CD4 and CD8 and analyzed by flow cytometry. Numbers in each quadrant indicate the percentage of cells in each region against the total. (D) Total number of live cells present in each thymic lobe from C57BL/6 (WT), CD28-deficient (CD28-), CD28-deficient scurfy [CD28- scurfy], and CD28-sufficient scurfy (scurfy) mice (mean ± SD, n = 3).