Figure 5. CD5^hi T cells with the greatest reactivity for self-antigens dominate the response to diverse foreign antigens.

(A and B) Experimental setup: congenically marked 15–20% CD5^lo or CD5^hi naïve CD4⁺ T cells were sorted, labeled with CFSE, mixed in a ~1:1 ratio and adoptively transferred to CD45.2⁺ recipients that were then infected with Listeria monocytogenes (LM), Influenza A virus or LCMV. (C) Fold change in CD5^hi:CD5^lo ratio in divided (CFSE^lo) versus undivided (CFSE^hi) transferred cells 7 days after infection. Each triangle or circle represents an individual mouse, lines denote means. Data summarized from 2–3 independent experiments. (D) Setup as in (A), but recipients were given anti-CD3 and anti-CD28 i.v.. The fold change in CD5^hi:CD5^lo ratio in divided versus undivided transferred cells and representative CFSE profiles 4 days after antibody administration are shown. (E) CD5 expression on antigen-specific CD4⁺ T cells identified using tetramers (2W1S:IA^b, left panel; LLO:IA^b, right panel) on days 0, 5, or 21 following LM infection. Each symbol represents an individual mouse and lines denote means. (F) CD5 expression on naïve (CD44^lo) and memory (CD44^hi) SMARTA and OT-II cells from TCR Tg mice. *P<0.05, **P<0.01.