Complex Memory T-Cell Phenotypes Revealed by Coexpression of CD62L and CCR7

Abstract

Antigen-experienced T cells have been divided into CD62L + CCR7 + central memory (T CM ) and CD62L − CCR7 − effector memory (T EM ) cells. Here, we examined coexpression of CD62L and CCR7 in lymphocytic choriomeningitis virus-specific memory CD8 T cells from both lymphoid and nonlymphoid tissues. Three main points emerged: firstly, memory cells frequently expressed a mixed CD62L − CCR7 + phenotype that differed from the phenotypes of classical T EM and T CM cells; secondly, T CM cells were not restricted to lymphoid organs but were also present in significant numbers in nonlymphoid tissues; and thirdly, a major shift from a T CM to T EM phenotype was found in memory cells that had been stimulated repetitively with antigen.