Granzyme-Producing CD4 T Cells in Cancer and Autoimmune Disease

CD4 T cells play important roles in promoting protective immunity and autoimmune disease. A great deal of attention has been given to the differentiation and function of subsets of cytokine-producing CD4 T cells (i.e., Th1, Th2, and Th17 cells) in these settings. However, others have also observed the accumulation of granzyme-producing CD4 T cells in tumors and in autoimmune patients that are distinct from their cytokine-producing counterparts. Despite the relatively large numbers of granzyme-producing cells in diseased tissues, their roles in driving disease have remained enigmatic. This review will focus on the phenotype(s) and roles of granzyme-producing CD4 T cells in cancer and autoimmunity. We will also examine how granzyme-producing cells interact with current therapeutics and speculate how they may be targeted during disease.