Fig. 5.

Transfer of TCR between CD8⁺ CTL populations is rapid and involves membrane exchange. Purified OT-I and B6.SJL P14 CD8⁺ T cells, stimulated separately as in Fig. 4 for 3 days, were cocultured and assessed for TCR and membrane transfer. (A) TCR exchange (dot plot and histogram), as detected using antibodies specific for OT-I (Vβ5.2) or P14 (Vβ8.1) TCR and populations discriminated by CD45 allotype. Histograms show percentage of CD8⁺ cells in coculture expressing exogenous TCR. (B) PKH-26 (membrane stain), CD45.2, and Vβ5.2 are rapidly and simultaneously transferred between cocultured OT-I cells and P14 cells. Values are percentage of P14 CD8⁺ cells in coculture acquiring the OT-I-specific markers. (C) Confocal images of interaction between stimulated OT-I and P14 cells, stained with PKH-26 and BODIPY, respectively. Arrows show merged membranes (yellow areas). (Scale bar: 10 μM.) (D) TCR transfer from stimulated OT-I cells to stimulated P14 cells (1-h coculture) in the presence of latrunculin B (Lat-B) or DMSO as control.