PD-L1 Immunohistochemical Detection in Tumor Cells and Tumor Microenvironment: Main Considerations on the Use of Tissue Micro Arrays.

Gerardo Botti,Monica Cantile,Giosuè Scognamiglio

doi:10.3390/ijms17071046

Abstract

PD-1/PD-L1 (programmed death 1/programmed death ligand 1) pathway plays a critical role in immune escape of tumor cells. Recent studies have described that PD-L1 is heterogeneously expressed in various types of cancer, although its prognostic/predictive value is still uncertain. These problems are partly due to a not well defined operating protocol for its detection by immunohistochemistry, but also because most of the studies conducted on large case series were made by Tissue Micro Array (TMA). We are going to discuss this latter point, to highlight that TMA must be set up in an appropriate manner, especially for some markers, such as PD-L1, which, besides being poorly expressed in tumor cells, can be expressed by cells of the tumor microenvironment.

Highlights

PD-1/PD-L1 pathway plays a critical role in immune escape of tumor cells
Several studies have recently shown that the PD-1/PD-L1 pathway may have a key role in the interaction of tumor cells with host immune response, and PD-L1 expression in tumor cells may function as a mechanism of adaptive immune resistance
Despite the importance of PD1/PD-L1 interaction in tumor elusion, the exact mechanism of how PD1/PD-L1 interaction affects tumor microenvironments to promote the escape of tumor cells from anti-tumor immuno-surveillance is not clear

Summary

Introduction

PD-1/PD-L1 (programmed death 1/programmed death ligand 1) pathway plays a critical role in immune escape of tumor cells. PD-L1 is a checkpoint receptor that plays an immune-regulatory role in T-cell activation, tolerance and immune-mediated tissue damage [1]. Several studies have recently shown that the PD-1/PD-L1 pathway may have a key role in the interaction of tumor cells with host immune response, and PD-L1 expression in tumor cells may function as a mechanism of adaptive immune resistance.

Results

Conclusion