Expression of PD-1 by T Cells in Malignant Glioma Patients Reflects Exhaustion and Activation

Abstract

Purpose: Glioblastoma (GBM) is the most common primary malignant tumor in the central nervous system. Our recent preclinical work has suggested that PD-1/PD-L1 plays an important immunoregulatory role to limit effective antitumor T-cell responses induced by active immunotherapy. However, little is known about the functional role that PD-1 plays on human T lymphocytes in patients with malignant glioma. Experimental Design: In this study, we examined the immune landscape and function of PD-1 expression by T cells from tumor and peripheral blood in patients with malignant glioma. Results: We found several differences between PD-1 þ tumor-infiltrating lymphocytes (TIL) and patient-matched PD-1 þ peripheral blood T lymphocytes. Phenotypically, PD-1 þ TILs exhibited higher expression of markers of activation and exhaustion than peripheral blood PD-1 þ T cells, which instead had increased markers of memory. A comparison of the T-cell receptor variable chain populations revealed decreased diversity in T cells that expressed PD-1, regardless of the location obtained. Functionally, peripheral blood PD-1 þ T cells had a significantly increased proliferative capacity upon activation compared with PD-1 À T cells. Conclusions: Our evidence suggests that PD-1 expression in patients with glioma reflects chronically activated effector T cells that display hallmarks of memory and exhaustion depending on its anatomic location. The decreased diversity in PD-1 þ T cells suggests that the PD-1-expressing population has a narrower range of cognate antigen targets compared with the PD-1 nonexpression population. This information can be used to inform how we interpret immune responses to PD-1-blocking therapies or other immunotherapies.

Immunohistochemical Characterization of Immune Infiltrate in Tumor Microenvironment of Glioblastoma

“…Several recent reports characterize the severe exhaustion signature of T-cells in glioblastoma [ 48 ] and functional hyporesponsiveness [ 49 ]. It has been proposed that distinct co-inhibitory mechanisms are involved; besides the PD-L1/PD-1 axis, LAG3 and, more recently, TIGIT have been detected in glioblastoma T-cells [ 50 , 51 ].…”

Progress and applications of mass cytometry in sketching immune landscapes

“…With relative high cellular throughput and high dimensions, CyTOF is an ideal and potent technique that reveals intratumor heterogeneity in a variety of tumors, including breast, [70][71][72][73] lung, [74][75][76][77] oropharyngeal, 78 brain, [79][80][81][82][83] colon, 7,11,84,85 ovarian, 86,87 kidney, 88,89 gastric cancer, 90,91 leukemia and lymphoma, 19,[92][93][94][95] and melanoma. 96,97 A summary of single-cell CyTOF studies on primary tumors of various human cancers is presented in Table 3.…”

Neural Stem Cells Secreting Bispecific T Cell Engager to Induce Selective Anti-Glioma Activity

“…The half-maximal effective/binding concentration (EC50) of the tested BiTEs in the binding or killing assays was determined by fitting data into the nonlinear regression using CD25, in cells isolated from PB and TILs as evaluated by flow cytometry (n≥7). GBM12 51 Cr killing assay determined the reengagement of PB and TILs from GBM E) patient1 and F) patient2 into glioma killing in the presence of BiTE LLON and CD2CD3CD28 beads (Stim. ), but not BiTE LLOFF or not stimulation (No stim.)…”

“…In experiments with BiTEs dose-response concentrations of the recombinant protein were as specified. In experiments with fixed BiTE concentrations, 5μg/mL of BiTE protein was used, and in fixed T: E ratios, the 1:20 was used.The cytotoxic activity of T cells against glioma cells in the presence of the BiTE proteins or NSCs secreting BiTE proteins was determined using standard51 Cr release assay. Depending on the assay, increasing T:E cell ratios or BiTE concentration were used as specified in the result section.…”