Detection and functional evaluation of arginase-1 isolated from human PMNs and murine MDSC

Immunotherapy has emerged as a potent alternative for cancer treatment, unfortunately, the clinical benefit remains limited to few patients and immunotherapy resistance due to immunosuppressive tumor microenvironment represents the major reason of such a failure. Arginase-1 is one of the enzymes contributing to the establishment of such immunosuppression. Among the human immune cells, polymorphonuclear cells (PMNs) represent the major source of arginase-1, while myeloid-derived suppressor cells (MDSCs) are the main arginase-1 producing cells in mice. Due to arginase-1 potential impact in dampening the immune response, there is a growing interest in assaying arginase-1 levels and functions. Thus, in this chapter we propose how to evaluate the expression and activity of arginase in human peripheral blood-derived PMNs and in MDSCs isolated from tumor-bearing mice.