Tumor-infiltrating CD39+ CD4+ Foxp3neg cells: an unknown population with features of exhaustion

RODRIGUEZ C; ACOSTA RODRIGUEZ EV; BOSSIO SN; PIAGGIO E; MONTES CL; ABRATE C; GRUPPI A

Congreso; LXVII Reunión Anual de la SAI.; 2019

The role of the CD4+T cells in the immune response against cancer is poorlyunderstood. Previously we demonstrated that tumors from tumor bearing-mice showedan important infiltrate of FOXP3neg CD4+ cells (Tconv) expressing CD39. CD39 is anecto-enzyme capable to hydrolyze extracellular ATP within the tumormicroenvironment. We aim to determine if this CD39+Tconv population exhibit aphenotype associated to exhaustion. C57BL/6 mice were injected with B16F10-OVAcancer cells and tumors were extracted on day 17. We detected that CD39+Tconvexhibit an increased expression of PD-1, Lag-3, TIGIT and CTLA-4 compared to theexpression on CD39-Tconv cells (p≤0.05 for all). Within CD39+Tconv cells, 78%expressed inhibitory Receptors (iRs). Around 30% of this population expressed one,34% co-expressed 2 while 14% co-expressed 3 iRs. Despite of 30% of CD39-Tconvexpressed iRs, most of them expressed only one. The analysis of transcription factorsshowed an increased expression of T-bet, Eomes, Helios, c-Maf and Blimp-1 inCD39+Tconv compared to CD39-Tconv (p≤0.05 for all). CD39+Tconv depicted ahigher frequency of Ki67+ cells than their counterpart (p≤0.01). Adoptive transfer ofOTII CD39-cells to B16-OVA injected WT mice demonstrated that 98,08±1,73% of OTIIcells in lymph nodes expressed CD39, indicating that tumor antigen specific T cellsacquired the ecto-enzyme expression. The study of breast cancer patients unveiled anexpansion of CD39+Tconv in tumors that was more evident comparing to juxtatumor(p≤0.01). Altogether these results indicate that CD39+Tconv cells represent anheterogeneous population within tumor microenvironment with features of exhaustion.Further studies will confirm the hypothesis.