CD29 Enriches for Cytotoxic Human CD4+ T Cells

CD4 + T cells are key contributors in the induction of adaptive immune responses against pathogens. Even though CD4 + T cells are primarily classified as noncytotoxic helper T cells, it has become appreciated that a subset of CD4 + T cells is cytotoxic. However, tools to identify these cytotoxic CD4 + T cells are lacking. We recently showed that CD29 (integrin β1, ITGB1) expression on human CD8 + T cells enriches for the most potent cytotoxic T cells. In this study, we questioned whether CD29 expression also associates with cytotoxic CD4 + T cells. We show that human peripheral blood-derived CD29 hi CD4 + T cells display a cytotoxic gene expression profile, which closely resembles that of CD29 hi cytotoxic CD8 + T cells. This CD29 hi cytotoxic phenotype was observed ex vivo and was maintained in in vitro cultures. CD29 expression enriched for CD4 + T cells, which effectively produced the proinflammatory cytokines IFN-γ, IL-2, and TNF-α, and cytotoxic molecules. Lastly, CD29-expressing CD4 + T cells transduced with a MART1-specific TCR showed target cell killing in vitro. In conclusion, we demonstrate in this study that CD29 can be employed to enrich for cytotoxic human CD4 + T cells.