Dysfunctional or exhausted T cells arise in chronic diseases including chronic viral infections and cancer, and express high levels of co-inhibitory receptors. Therapeutic blockade of these receptors has clinical efficacy in the treatment of cancer. While co-inhibitory receptors are co-expressed, the triggers that induce them and the transcriptional regulators that drive their co-expression have not been identified. The immunoregulatory cytokine IL-27 induces a gene module in T cells that includes several known co-inhibitory receptors (Tim-3, Lag-3, and TIGIT). The present invention provides a novel immunoregulatory network as well as novel cell surface molecules that have an inhibitory function in the tumor microenvironment. The present invention further provides the novel discovery that the transcription factors Prdm1 and c-Maf cooperatively regulate the expression of the co-inhibitory receptor module. This critical molecular circuit underlies the co-expression of co-inhibitory receptors in dysfunctional T cells and identifies novel regulators of T cell dysfunction.

Described herein are novel compositions comprising IL-27 or NFIL-3 modulators (i e , inhibitors or activators), and methods using these agents for targeting cells, such as functionally exhausted or unresponsive immune cells, and modulating TIM-3 activity or expression. These compositions, methods, and uses are useful for the treatment of chronic immune conditions, such as persistent infections, cancer, and autoimmune diseases.