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Original citation: J Clin Invest. 2015;125(11):4053-4062. https://doi.org/10.1172/JCI81187. Citation for this retraction: J Clin Invest. 2024;134(13):e183278. https://doi.org/10.1172/JCI183278. QIMR Berghofer Medical Research Institute recently notified the JCI of concerns regarding Figure 4B [...]

Coinhibitory receptors are critical for the maintenance of immune homeostasis. Upregulation of these receptors on effector T cells terminates T cell responses, while their expression on Tregs promotes their suppressor function. Understanding the function of coinhibitory receptors in effector T cells and Tregs is crucial, as therapies that target coinhibitory receptors are currently at the forefront of treatment strategies for cancer and other chronic diseases. T cell Ig and ITIM domain (TIGIT) is a recently identified coinhibitory receptor that is found on the surface of a variety of lymphoid cells, and its role in immune regulation is just beginning to be elucidated. We examined TIGIT-mediated immune regulation in different murine cancer models and determined that TIGIT marks the most dysfunctional subset of [CD8.sup.+] T cells in tumor tissue as well as tumortissue Tregs with a highly active and suppressive phenotype. We demonstrated that TIGIT signaling in Tregs directs their phenotype and that TIGIT primarily suppresses antitumor immunity via Tregs and not [CD8.sup.+] T cells. Moreover, [TIGIT.sup.+] Tregs upregulated expression of the coinhibitory receptor TIM-3 in tumor tissue, and TIM-3 and TIGIT synergized to suppress antitumor immune responses. Our findings provide mechanistic insight into how TIGIT regulates immune responses in chronic disease settings., Introduction T cell responses are controlled by multiple receptors: while costimulatory receptors ensure optimal T cell activation and proliferation to generate a protective immune response, coinhibitory or checkpoint receptors dampen [...]