Cutting Edge: The Signals for the Generation of T Cell Memory Are Qualitatively Different Depending on TCR Ligand Strength

CD8 T cell memory critically contributes to long-term immunity. Both low- and high-affinity TCR signals are able to support the differentiation of memory CD8 T cells. However, it is unclear whether the requirements for memory development change when TCR signal strength is altered. To gain further insight into this question, we used a TCR beta transmembrane domain mutant model that is defective in the generation of memory in response to high-affinity ligands. Surprisingly, lowering TCR signal strength, by stimulation with low- affinity ligands, resulted in normal memory development. Restoration of memory correlated with recovery of TCR-dependent NF-kappa B signaling. Thus, these data provide novel evidence that the requirements for memory are qualitatively different depending on TCR signal strength.