GSE128197
CD4+ resident memory T cells dominate immunosurveillance and orchestrate local recall responses
This study examines the extent to which memory CD4+ T cells share immunosurveillance strategies with CD8+ resident memory T cells (TRM). After acute viral infection, memory CD4+ T cells predominantly utilized residence to survey nonlymphoid tissues, albeit not as stringently as observed for CD8+ T cells. In contrast, memory CD4+ T cells were more likely to be resident within lymphoid organs than CD8+ T cells. Migration properties of memory-phenotype CD4+ T cells in non-SPF parabionts were similar, generalizing these results to diverse infections and conditions. CD4+ and CD8+ TRM shared overlapping transcriptional signatures and location-specific features, such as granzyme B expression in the small intestine, revealing tissue-specific and migration property-specific, in addition to lineage-specific, differentiation programs. Functionally, mucosal CD4+ TRM reactivation locally triggered both chemokine expression and broad immune cell activation. Thus, residence provides a dominant mechanism for regionalizing CD4+ T cell immunity, and location enforces shared transcriptional, phenotypic, and functional properties with CD8+ T cells. Overall design: 17 samples were analyzed by RNA-Sequencing: 3 replicates of resident memory SMARTA CD4 cells (CD62L- CD69+)  from the female reproductive tract (FRT) , 2 replicates of resident memory SMARTA CD4 cells (CD62L- CD69+)  from the small intestine epithelium (IEL), 3 replicates of resident memory SMARTA CD4 cells (CD62L- CD69+) small intestine lamina propria (LP), 3 replicates of resident memory SMARTA CD4 cells (CD62L- CD69+) from the spleen (SLO), 3 replicates of SMARTA CD4 cells (CD62L+ CD69- or TCM) from the spleen of mice, and 3 replicates of SMARTA CD4 cells (CD62L- CD69- or TEM)  from the spleen of mice infected with LCMV-Armstrong 54 days prior.