CD45RB Status of CD8+ T Cell Memory Defines T Cell Receptor Affinity and Persistence

Abstract

Summary: The identity of CD45 isoforms on the T cell surface changes following the activation of naive T cells and impacts intracellular signaling. In this study, we find that the anti-viral memory CD8+ T pool is unexpectedly comprised of both CD45RBhi and CD45RBlo populations. Relative to CD45RBlo memory T cells, CD45RBhi memory T cells have lower affinity and display greater clonal diversity, as well as a persistent CD27hi phenotype. The CD45RBhi memory population displays a homeostatic survival advantage in vivo relative to CD45RBlo memory, and long-lived high-affinity cells that persisted long term convert from CD45RBlo to CD45RBhi. Human CD45RO+ memory is comprised of both CD45RBhi and CD45RBlo populations with distinct phenotypes, and antigen-specific memory to two viruses is predominantly CD45RBhi. These data demonstrate that CD45RB status is distinct from the conventional central/effector T cell memory classification and has potential utility for monitoring and characterizing pathogen-specific CD8+ T cell responses. : Krummey et al. show that viral CD8+ T cell memory has heterogeneous CD45 isoform expression. Low-affinity CD8+ T cells have high CD45RB expression and a CD27hiCD62Lhi phenotype relative to high-affinity CD45RBlo CD8+ T cells, which possess an effector-like phenotype. CD45RBhi cells survive better under homeostatic conditions in vivo. Keywords: T cell memory, TCR affinity, CD45