Agonistic antibodies were diluted with sterile PBS and each well of a non-TC treated 96-well plate was coated with a volume of 50 muL for approximately 16 h at 4 C. Wells were rinsed twice with PBS prior to addition of T cells in complete MEM medium (phenol red-free MEM supplemented with 10% FBS, 2 mM glutamine, non-essential amino acids, penicillin and streptomycin, 1 mM sodium pyruvate, 50 muM 2-mercaptoethanol, and 10 mM HEPES).