TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor (3 (TGF-(3) directly acts on naive, effector, and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-(3 signaling. TGF-(3 availability is altered by infections and cancer; however, the dose- dependent effects of TGF-(3 on memory CD8 T cell (T-mem) reactivation are still poorly defined. We examined how activation and TGF-(3 signals interact to shape the functional outcome of T-mem reactivation. We found that TGF-(3 could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or proinflammatory signals. In contrast, even high doses of TGF-(3 had a comparatively modest effect on IFN-gamma expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-(3 signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-(3 signals is of importance. We found that exposure to TGF-(3 before or after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-(3 altered similar to 10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-(3-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-(3 is not simply suppressing CD8 T-mem but modifies functional and chemotactic properties in context of their reactivation signals and in a dose- dependent manner.