Figure 6. OT-1 Cells Proliferating in Irradiated B6 and ss-R4TAP° Mice Do Not Become Cytotoxic Effector Cells.

CD8⁺Vα2⁺ cells (2 × 10⁶) from OT-1 RAG° mice were CFSE labeled and injected into irradiated B6 (triangles), ss-R4TAP° (diamonds), or ss-OVApTAP° (circles) hosts. Spleen cells were harvested on day 4 and assayed for lysis of OVAp-coated EL4 targets. Flow cytometry revealed that transferred OT-1 Vα2⁺CD8⁺ cells represented 15%, 6%, and 75% of splenocytes recovered from B6, ss-R4TAP°, or ss-OVApTAP° hosts, respectively (data not shown). The E:T was based on the number of CD8⁺Vα2⁺ cells used as effectors. The wells were normalized for total cell number by diluting cells recovered from B6 (triangles) and ss-OVApTAP° hosts (filled circles) with fresh B6 splenocytes to 6% CD8⁺Vα2⁺ cells, or cells recovered from ss-OVApTAP° hosts were used undiluted (open circles). For all effectors at all E:T ratios, lysis of EL4 targets in the absence of peptide was less than 3% (data not shown).