CD39 delineates cell exhaustion in mouse and human tumor-associated CD8+ T cells: a possible immunomodulatory role of a ?dysfunctional cell subset?

CANALE, FERNANDO P.; RAMELLO, MARÍA C.; NÚÑEZ, NICOLÁS; FURLAN, CINTIA L. ARAUJO; SERRÁN, MELISA GOROSITO; BOARI, JIMENA TOSELLO; BOSSIO, SABRINA N.; DEL CASTILLO, ANDRÉS; LEDESMA, MARTA; SEDLIK, CHRISTINE; PIAGGIO, ELIANE; GRUPPI, ADRIANA; RODRÍGUEZ, EVA V. ACOSTA; MONTES, CAROLINA L.

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2016

Tumor-infltrating CD8+ T lymphocytes (CD8+ TILs) are crucialto eliminate tumors through cytotoxicity and cytokine production.Cancer cells blunt this process developing a microenvironment thatinduces dysfunctional and regulatory T cells. Here, we aimed tostudy by flow cytometry the expression of the immunomodulatoryecto-enzyme CD39 on CD8+ T cells in the context of anti-tumorresponse. Studying B16F10-OVA and other mouse cancer models,we defned three subsets: CD39-, CD39int and CD39high CD8+ Tcells, being the latter predominant in tumors but absent in lymphoidorgans (p≤0.0001). Of note, the frequency of CD39high CD8+TILs increased with tumor growth (p≤0.0001). CD39high CD8+TILs exhibited an exhausted phenotype with lower production ofTNF (p≤0.001) and IL-2 (p≤0.01) than CD39-/CD39int CD8+TILs, and higher expression of inhibitory receptors (PD-1, Tim-3,LAG-3, TIGIT and 2B4) (p≤0.0001 for all). Murine exhaustedCD8+ T cells displayed high ability to hydrolyze extracellular ATPin vitro, indicating that CD39 is enzymatically active on thesecells. Moreover, co-culture experiments showed that exhaustedCD8+ TILs are able to reduce IFNã production by conventionalCD8+ T cells (p≤0.05). Interestingly, in samples from 29 breastcancer and 4 melanoma patients we observed that CD39+ CD8+T cells were present in tumors and increased in invaded/metastaticlymph nodes compared to non-invaded lymph nodes (p≤0.001),while absent in peripheral blood. These cells exhibited impairedproduction of IFNã (p≤0.001), TNF (p≤0.01) and IL-2 (p≤0.05in lymph nodes) when compared to CD39- CD8+ T cells, andhigher expression of PD-1 (p≤0.01), TIGIT (p≤0.01) and BTLA(p≤0.05). These fndings suggest that beside the loss of effectorfunctions, the tumor environment also drives the acquisition ofregulatory molecules on CD8+ T cells. CD39 may emerge notonly as a marker of CD8+ T cell dysfunction but also as a possible target for treatments aimed to restore anti-tumor immunity