Peripheral blood mononuclear cells (PBMC) are suspended at a concentration of 1Å~106 cell per mL in T cell medium containing 50 ng/mL of the anti-CD3 monoclonal antibody OKT3 and 300 IU/mL of IL-2. OKT3 is added directly to media as solubilized OKT3 and is used for the initial stimulation of PBMC. But when you use a specific subpopulation of T cells (CD8 or CD4), what is the best reagent for T cell activation in vitro? I have doubts about the use of Dynabeads® Human T-Activator CD3/CD28 or CD3 Monoclonal Antibody (OKT3), Functional Grade, eBioscience™. Can you help me? thanks