CD4 and acute lymphoblastic leukemia: In direct comparisons with wild-type CD8, incorporation of the S53G or S53N variants enhanced the production of IFN-γ by 1E9 TCR-transduced primary CD4+ T cells cocultured with K562 HLA-A2+CD20 cells but not with K562 HLA-A2 cells, and incorporation of the S53N variant enhanced the production of IFN-γ by 1E9 TCR-transduced primary CD4+ T cells cocultured with ALL CM cells, consistent with an effect specific for CD20 (Fig. 4, A and B).