Diverse in vitro response of CD8⁺ and CD4⁺ subpopulations of human PBMCs to hOKT3γ1(Ala-Ala) stimulation. CFSE-labeled PBMCs were cultured in the presence of hOKT3γ1(Ala-Ala) (A and B) or PHA (C and D) for 6 days. Cells were labeled with fluorochrome-conjugated anti-CD4 and anti-CD8 and analyzed by flow cytometry. (A and C) CD8-gated cells. (B and D) CD4-gated cells. Gray histograms: cells without stimulation. Results from a single experiment representative of 6 experiments are shown.