ECP-treated splenocytes reduce CD8⁺IFN-γ⁺ effector T cells in vivo. C3H.SW recipient mice received 5.0 × 10⁶ bone marrow and 10⁶ T cells from syngeneic (C3H.SW) or allogeneic (B6-Ly5.2) donors on day 0 followed by infusion of B6→C3H.SW ECP-treated cells on day 7. IFN-γ production by donor CD8⁺ effector cells was measured 96 hours later. (A) Representative flow cytometry data of unseparated splenocytes gated on whole-cell scatter. Percentage of donor (CD45.1⁺) CD8⁺ T cells in R4 (left) or producing IFN-γ (right) indicated. (B) Numbers of donor CD8⁺IFN-γ⁺ cells per spleen. ▩ versus ■, *P < .05. Data are means (± SD) pooled from 3 independent experiments (n = 9-20 per group).