Virtual memory T cells orchestrate extralymphoid responses conducive to resident memory.

ABSTRACT

A primary immune response is initiated in secondary lymphoid organs. Virtual memory CD8+ T (TVM) cells are antigen-inexperienced T cells of a central memory phenotype, acquired through self-antigen­driven homeostatic proliferation. Unexpectedly, we find that TVM cells are composed of CCR2+ and CCR2− subsets that differentially elaborate a spectrum of effector- and memory-poised functions directly in the tissue. During a primary influenza infection, TVM cells rapidly infiltrate the lungs in the first day after infection and promote early viral control. TVM cells that recognize viral antigen are retained in the tissue, clonally expand independent of secondary lymphoid organs, and give rise to tissue-resident memory cells. By orchestrating an extralymphoid primary response, heterogenous TVM cells bridge innate reaction and adaptive memory directly in the infected tissue.