CD8+ T CELLS UP-REGULATE CD39 EXPRESSION AND INHIBITORY RECEPTORS UPON IN VITRO TCR AND CYTOKINES STIMULATION.

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

Mar del Plata

Congreso; Reunión Conjunta SAIC SAI SAFIS 2018; 2018

Previously we have shown that the frequency of exhausted CD39highCD8+ T cells increased with tumor growth but was absent in lymphoid organs. We aimed to evaluate signals that may influence CD39 and inhibitory receptors (IRc) upregulation on CD8+T cells. Purified CD8+ T cells from draining lymph node of B16F10-OVA tumor bearing mice were stimulated during 48hs with αCD3/αCD28 in presence or absence of IL-6 or conditioned medium (CM) obtained by culturing tumors from B16F10-OVA bearing mice. Then cells were resting in IL-2 (96hs) and re-stimulated with αCD3/αCD28 (24hs). We observed that after TCR stimulation, the frequency of CD39+ and PD-1+TIM-3+ CD8+T cells were (27.3%±8.1% and 50.57%±0.46% respectively), however the frequency of both populations was not increase by neither MC nor IL-6. Next we stimulated the CD8+ T cells reducing the resting with IL-2 (24hs) in presence or absence of IL-6, IL-27 or CM. We found that TCR stimulation increased significantly the % of CD39+CD8+ T cells (p≤0.05) respect to non-stimulated cells, and the frequency of the CD39+ expressing cells decreased in absence of IL-2 (p≤0.05). The stimulation with cytokines associated with exhaustion such as IL-27 or a combination of IL-6/IL-27 increased the frequency of CD39+ cells (p<0.01 for both), while this frequency was not modified in presence of IL-6 or CM respect to TCR-stimulated control cells. Upon TCR stimulation the % of both PD-1+ and TIM-3+ cells increased significantly respect to non-stimulated cells (p≤0.0001 and p≤0.01 respectively), however only IL-6 plus TCR stimulation triggered an increment of PD-1+ T cells frequency (p≤0.05). We showed that TCR stimulation induce CD39 on murine CD8+ T cells which is more evident when combining IL-6 and IL-27, indicating that CD39 expression may result as a consequence of the integration of different signals.