CD8+HLA-DR+ Tregs from human peripheral blood represent a differentiated but not exhausted Treg subset, acting through CTLA-4 and PD-1 molecules

P. BAZ; L. A. BILLORDO; MACHICOTE, ANDRÉS; L. FAINBOIM; S. BELEN

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAA,SAB,SAIC;SAIB;SAI;SAFE;SAH;SAP;SAFIS.

Introduction. We have previously shown that CD8+ T cells from both cord blood (CB) and adult peripheral blood (PB) constitutively expressingHLA-DR represent a human CD8+ regulatory T cell subset (CD8+DR+ Tregs), showing a strong suppressor capacity mediated by CTLA-4.Aims. To better characterize human PB CD8+DR+ Tregs, regarding their differentiation status and phenotype, including those molecules thatidentify exhausted cells, and to study the role of PD-1 in the suppression mechanism.Conclusions1. Cord blood CD8 cells expressing HLA-DR havea naïve phenotype, suggesting that its expressionis constitutive and may represent a distinctivelineage of CD8 cells.2. According to the lack of TIM-3 expression, thehigh levels of IFNg production, their ability todegranulate (high CD107a) and the highproliferative capacity, we conclude that CD8+HLADR+Tregs do not represent exhausted cells.3. PD-1 is revealed as a mediator of thesuppressor mechanism of CD8+HLA-DR+ Tregcells, which can be added to the previouslyreported suppressor effect induced by CTLA-4.