Phenotypic and functional characterization of CD39+CD4+ conventional T lymphocytes from B16F10-OVA tumor-bearing mice

MONTES, CAROLINA L.; RODRÍGUEZ, EVA V. ACOSTA; GRUPPI, ADRIANA; RODRIGEZ, CONSTANZA; ABRATE, CAROLINA; CANALE, FERNANDO P.; BOSSIO, SABRINA N.

Congreso; Reunión Conjunta de las Sociedades de Biociencias. LXV Reunión Anual de la SAI 2017; 2017

The enzymatic activities of CD39 and CD73 play key roles in the modulation of signals delivered in the tumor microenvironment (TME) through the conversion of ADP/ATP to adenosine. We aimed to study the expression of CD39 on conventional Foxp3- CD4+ T cells (Tconv) from tumor-bearing mice by flow cytometry. C57BL/6 mice were injected with B16F10-OVA cancer cells. Tumors, spleens and draining lymph nodes (dLN) were extracted on day 17. We observed increased frequency of CD39CD73-expressing Tconv in tumor respect to spleen (p≤0.001) and dLN (p≤0.001). This population, together with CD39-CD73+ Tconv showed higher expression of CD26 compared to CD73- Tconv. In tumors, we detected that 18,5±2,6% of CD39+ Tconv co-express PD-1 and LAG-3, and 15,8±6,6% express TIGIT. In addition, PD-L1 expression was increased on this population compared to CD39- Tconv (p≤0.01). We observed that 89,4±2,7% of tumor-infiltrating CD39+ Tconv exhibited effector memory phenotype. Around 50% of this cells were CD49d+ CD11a+, a phenotype associated with antigenic stimulation. The effector function of these cells was assessed analyzing their ability to produce cytokines upon activation. Within CD39+ Tconv we detected decreased frequency of TNF-producing cells, but higher frequency of IFNγ-producing cells compared to CD39- Tconv (p≤0.01 for all). In concordance, CD39+ Tconv showed high expression of T-bet. Also, CD39+ Tconv exhibited higher frequency of CD107a+ and Granzyme B+ cells than their CD39- counterparts. CD39+Tconv did not produce IL-2. Using Hypoxyprobe-1 reagent, we found a higher frequency of hypoxic cells within the subset CD39+ Tconv compared to CD39- Tconv (p≤0.01). Together these results suggest that TME drives the acquisition of immunoregulatory molecules on Tconv and postulate CD39 as a relevant target to be deeply studied in order to understand how this molecule expressed on Tconv may influence the anti-tumor immune response.