The CD4 molecule contributes to the greater cytotoxic potential of CD4^dimCD8^bright T cells compared with CD4⁻CD8⁺ T cells. (A-H) Cumulative data (A,F) and representative dot plots (B-E,G-J) of CD107ab staining by CD4⁻CD8⁺ and CD4^dimCD8^bright T cells from HIV⁺ LTNP (A-E) and CMV⁺ (F-J) donors, cocultured with T1 target cells with no blocker (A-B,F-G), after blocking targets with MHC-II blocking antibody(A,C,F,H), or CD4 neutralizing antibody (A,D,F,I) or cocultured with T2 targets (A,E,F,J). (A,F) Data represent mean + SD percentage of 107ab expression from at least 3 donors. P values between groups are indicated within the figure and based on 2-tailed unpaired t test analysis.