TOX1 defines the function of CD8+ T lymphocytes in regulating exhaustion-associated markers 9031

Abstract Description Thymocyte selection-associated high mobility group box (TOX) transcription factors are highly expressed in the thymus. In humans, TOX1 expression is induced by intense or chronic exposure of the T cell receptor (TCR) to antigen. Recent studies have linked TOX1 expression to the exhausted phenotype of CD8+ T cells observed during chronic infection and tumor development. TOX1 has also been identified as a regulator for the survival of exhausted CD8+ T cells. In this study, we introduce a novel monoclonal antibody that detects mouse and human TOX1 by intracellular flowcytometry, Western blot and immunocytochemistry. The specificity of the TOX1 antibody was confirmed using a TOX subfamily (TOX1-4) loss of function model. TOX1 was detected by intracellular flow cytometric analysis of a T lymphoblast cell line and human CD8+ naïve and memory T cells. We found increased expression of TOX1 along with increased expression of several inhibitory receptors (including PD1, LAG3 & CD39), cytolytic proteins (including granzyme B and perforin), transcription factors Eomes and T-bet and the chemokine receptor CX3CR1. We also observed that in vitro exhaustion of CD8+ T lymphocytes promote cell death in memory T cells in contrast to naive T cells. In summary, our study demonstrates the specificity of our TOX1 antibody in multiple applications and establishes TOX1 as a potential regulator and phenotypic marker for exhausted cells that promote cell death after chronic TCR stimulation. Funding Sources N/A Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)