Antigenic requirements for CD8⁺ T-cell expansion in DNRII Tg mice. (A) Lymphocytes from 8- to 10-week-old female (i) and male (ii) DNRII Tg, HY TCR Tg, or DNRII, HY TCR double-transgenic mice were analyzed for CD44^hi (MFI, greater than 100) cell-surface expression on the CD8⁺ T-cell population. Data are represented as the average percentage of CD44^hi cells in each T-cell subset; error bars represent the SD in each group (each group included 3 or more mice). (B) Lymphocytes from 8- to 10-week-old female DNRII Tg, 2C TCR Tg, or DNRII, 2C TCR double-transgenic mice were analyzed for CD44^hi (MFI, greater than 100) cell-surface expression on the CD8⁺ T-cell population. Data are represented as the average percentage of CD44^hi cells in each T-cell subset; error bars represent the SD in each group (each group included 3 or more mice). (C) Purified, CFSE-labeled DNRII Tg T cells from 10-week-old homozygous Tg mice were injected into TAP-1 KO or age-matched C57BL/6 hosts. Hosts were killed, and lymphocytes from lymph nodes were pooled and analyzed for CFSE⁺ T cells 1 week after injection. Data are represented as the average percentage of CFSE⁺, CD8⁺ T cells in each cell division group. Error bars represent the SD in each group (n = 3), with asterisks denoting significant (P < .05) differences between C57BL/6 and Tap KO hosts. The experiment was performed 3 times with similar results (total n = 10/group).