Most potent stimulator of naive T cell is
High-Yield Explanation
Ref Robbins 9/e p191 Naive T cells leave the thymus and home to secondary lymphoid organs. Dendritic cells are the most potent activators of naive T cells. DCs carry antigen from the periphery to the draining lymph nodes. ... CD28 signaling provides "Signal 2" to T cells and is necessary for T cell activation.