Hi, I sorted NAIVE CD4 T cells from mouse spleen and lymph nodes, and cultured cells in medium (RPMI1640 + Pen/Strep + 10%FBS + beta-mercaptoethanol + Glutamax-I + Sodium Pyruvate + HEPES) in a 48-well flat-bottom plate, which was coated in advance with anti-CD3 2.5 or 5 ug/ml, at 4℃ overnight. And the input cell # was 0.35*10^6 in 700ul medium. At Day 3, I detected cells using flow cytometrey, and found that >90% were dead. I set a control cultured under anti-CD3 and Anti-CD28, cells were ok. Previously, I also cultured TOTAL CD4 T cells with only anti-CD3, no problem. So, could NAIVE CD4 T cells be cultured in medium with only anti-CD3? Thanks a lot.