Anti-CTLA-4 treatment promote the expansion of CD39+ conventional CD4+ T cells.

BOSSIO, SABRINA N.; ABRATE, CAROLINA; CONSTANZA RODRIGUEZ; ADRIANA GRUPPI; ACOSTA RODRÍGUEZ, E.V.; CAROLINA LUCÍA MONTES

Congreso; Congreso Anual de la Sociedad Argentina de Inmunología 2021.; 2021

Previously we demonstrated that tumors from different experimental mice models are infiltrated with FOXP3- CD4+ cells (Tconv) expressing CD39. CD39 is an unequivocal marker CD8+ of exhaustion. Tumor infiltrating (TI) CD39+Tconv cells represent an heterogeneous population with features of exhaustion. Transcriptional profiling of TI-CD39+Tconv cells showed that they exhibit a transcriptional signature associated with cytotoxic CD4+ T cells. We aim to evaluate the impact of Anti-CTLA-4 treatment on TI-CD39+Tconv cells. C57BL7/6 mice were injected 0.5x106 MC38 tumor cells. On days, 4, 7 and 10 mice were treated with anti-CTLA-4 (100ug/mice) or IgG (Control). On day 17 we evaluated by flow cytometry the phenotype of the of TI-CD39+Tconv cells. As expected, anti?CTLA-4 treated mice exhibited reduced tumor volume and frequency of TI-Tregs respect to controls (p<0.001), however they showed higher frequency TI-CD39+Tconv cells (p<0.01). UMAP visualization analysis based on the expression levels of 8 Molecules on TI-Tconv cells from treated and control mice shown 10 different clusters. After treatment, clusters corresponding to FOXP3+ (Tregs) cells are almost absent; however, 2 clusters corresponding to CD39+ and inhibitor receptors (PD-1, 2B4, TIGIT, LAG-3) expressing cells are enriched. Interestingly one cluster of these enriched clusters, exhibit higher expression of CD39 and PD-1. The evaluation of transcription factors related to exhaustion (TOX, Eomes, Helios) or pre-exhaustion (TCF-1) as well as CD107a (a marker of cytolytic capability) revealed no differences in the expression of all these markers on TI-CD39+Tconv cells from treated or control mice. All together, we conclude that the anti-CTLA-4 treatment expand the TI-CD39+Tconv cells, and has no significant impact in the phenotype or function of this population, that due to the cytotoxic potential may contribute to the immune response against tumors.