CD3/CD28-costimulated T1 and T2 subsets: differential in vivo allosensitization generates distinct GVT and GVHD effects.

Adoptive T-cell therapy using CD3/CD28 co-stimulation likely requires in vivo generation of antigen specificity. Because CD28 promotes T H 1/T C 1 (T1) or T H 2/T C 2 (T2) differentiation, costimulation may generate donor T1 or T2 cells capable of differentially mediating allogeneic graft-versus-tumor (GVT) effects and graft-versus-host disease (GVHD). Costimulation under T1 or T2 conditions indeed generated murine T H 1/T C 1 cells secreting interleukin-2/interferon-γ (IL-2/IFN-γ) or T H 2/T C 2 cells secreting IL-4/IL-5/IL-10. In vivo, allogeneic T1 cells expanded, maintained T1 secretion, and acquired allospecificity involving IFN-γ and IL-5. In contrast, allogeneic T2 cells expanded less and maintained T2 secretion but did not develop significant allospecificity.Allogeneic, but not syngeneic, T1 cells mediated a GVT effect against host-type breast cancer cells, as median survival time (MST) increased from 25.6 ± 2.6 (tumor controls) to 69.2 ± 5.9 days ( P -9 ). This T1-associated GVT effect operated independently of fasL because T1 cells from gld mice mediated tumor-free survival. In contrast, allogeneic T2 cells mediated a modest, noncurative GVT effect (MST, 29 ± 1.3 days; P