PD-1+Tim-3+ T cells from 4TL tumor-bearing mice display features of exhaustion and increased expression of immunomodulatory molecules

CANALE F; RAMELLO MC; GOROSITO SERRÁN M; ARAUJO FURLÁN CL; TOSELLO BOARI J; ACOSTA RODRIGUEZ EV; GRUPPI A; MONTES CL

Congreso; LVII Reunión Anual de la Sociedad Argentina de Inmunología; 2014

T cell exhaustion is a T cell dysfunction state that arises during chronic infections and cancer. It is characterized by poor effector functions and sustained expression of inhibitory receptors (iRs) like PD-1 and TIM-3. Based on our previous findings, we hypothesize that these apparently dysfunctional T cells may have modulatory functions. In this work we studied phenotype and functional characteristics of tumor-infiltrating lymphocytes (TILs) and T cells from tumor-draining lymph nodes (dLN) of 4T1 mammary carcinoma bearing mice; comparing PD-1+TIM-3+ double positive (DP) cells with PD-1-TIM-3- double negative (DN) cells. Within DP TILs population we found higher % of cells expressing iRs like 2B4, LAG-3 and KLRG-1 compared to DN T cells, being 2B4 and LAG-3 more frequent in CD8+ DP T cells (p<0.001 for both) and KLRG-1 in CD4+ DP T cells (p<0.01). DP T cells from dLN exhibited the same pattern of iRs expression. Studying functional features, we observed that, after PMA/Ionomycin stimulation, CD8+ DP T cells from tumor and dLNs showed similar % of CD107a+ cells than control CD8+ T cells indicating that CD8+ DP T cells maintain their capacity to degranulate. As previously observed in TILs, CD4+ DP T cells from dLNs showed reduced % of TNF+ and IL2+ cells but higher % of IL-10+ cells than CD4+ DN T cells (p<0.01 for all cases). However, in dLNs we observed higher % of IFNγ+ and TGFβ+ CD4+ DP cells. CD4+ DP T cells from tumor showed higher expression of the transcription factor Blimp-1, which has been related with exhaustion (p<0.001) while CD4+ DP T cells from tumor and dLN revealed expression of Foxp3 and Helios, which points them as a possible subset of regulatory T cells. Analysis of immunomodulatory molecules showed that DP TILs exhibited higher expression of FasL than DN T cells (p<0.01) while DP T cells from dLNs expressed more PD-L1 (p<0.001). These findings suggest that ?exhausted? T cells could have a modulatory role, which may impact on tumor progression.