Inhibitory Receptor Expression Depends More Dominantly on Differentiation and Activation than “Exhaustion” of Human CD8 T Cells

Abstract

Under conditions of chronic antigen stimulation, such as persistent viral infection and cancer, CD8 T cells may diminish effector function, which has been termed “exhaustion.” Expression of inhibitory Receptors (iRs) is often regarded as a hallmark of “exhaustion.” Here we studied the expression of eight different iRs by CD8 T cells of healthy humans, including CTLA-4, PD1, TIM3, LAG3, 2B4, BTLA, CD160, and KLRG1. We show that many iRs are expressed upon activation, and with progressive differentiation to effector cells, even in absence of long-term (“chronic”) antigenic stimulation. In particular, we evaluated the direct relationship between iR expression and functionality in CD8 T cells by using anti-CD3 and anti-CD28 stimulation to stimulate all cells and differentiation subsets. We observed a striking up-regulation of certain iRs following the cytokine production wave, in agreement with the notion that iRs function as a negative feedback mechanism. Intriguingly, we found no major impairment of cytokine production in cells positive for a broad array of iRs, as previously shown for PD1 in healthy donors. Rather, the expression of the various iRs strongly correlated with T cell differentiation or activation states, or both. Furthermore, we analyzed CD8 T cells from lymph nodes (LNs) of melanoma patients. Interestingly, we found altered iR expression and lower cytokine production by T cells from metastatic LNs, but also from non-metastatic LNs, likely due to mechanisms which are not related to exhaustion. Together, our data shows that expression of iRs per se does not mark dysfunctional cells, but is rather tightly linked to activation and differentiation. This study highlights the importance of considering the status of activation and differentiation for the study and the clinical monitoring of CD8 T cells.

Blockade of LAG3 enhances responses of tumor-infiltrating T cells in mismatch repair-proficient liver metastases of colorectal cancer

“…4C). LAG3 expression is upregulated on T cells after activation and differentiation, 54 , 55 and intra-tumoral T cells that recognize tumor antigens are characterized by expression of LAG3 and other inhibitory receptors. 56 Although chronic tumor antigen stimulation in the tumor microenvironment can induce T cell exhaustion with simultaneous induction of high expression of multiple inhibitory receptors, this does not mean that all CD8 + TIL which express one or more inhibitory receptors at any level are functionally exhausted.…”

Tissue-resident memory T cells are epigenetically cytotoxic with signs of exhaustion in human urinary bladder cancer

“…S3). It is important to note that in this context PD‐1 acts as an indicator of T cell activation instead of exhaustion [41]. Therefore, T RM cells from the circulation may have a promising feature of activation following TCR engagement and possibly CD103/E‐cadherin ligation once they lodge in the tumour tissue [6, 42, 43].…”

Immunological markers and clinical outcome of advanced melanoma patients receiving ipilimumab plus fotemustine in the NIBIT-M1 study

“…It has been previously shown that the expression of inhibitory receptors, such as PD-1 and BTLA, on human CD8 C T cells correlated with the differentiation status and was not associated with their 'exhaustion' . 37 Furthermore, T cells isolated from tumor lesions expressing either PD-1 or BTLA identified clonally expanded tumor reactive T lymphocytes that, following T cell adoptive administrations into MM patients, mediated tumor regression. 38,39 Albeit future studies need to be performed to characterize ex vivo the functional role of the T cell subsets we have found to be associated with the clinical outcome of MM patients, they could represent candidate predictive or early on treatment biomarkers for IPI plus FTM treatment.…”