CD226 and neoplasm: Cluster 3 was characterized by a decrease of the following subsets: the T8 and T15 populations, with a central memory (CCR7/CD127+) phenotype; the CCR5+ T9 effector memory population, a subset necessary for maximal T-cell-mediated antitumor responses28; the CD103+ T13 population, thought to consist of tumor-reactive, tissue-resident memory T cells29,30; and the TCRgd-1 subset expressing markers of early differentiation (CD27, CD28), tissue homing (CCR5), and tumor cytotoxicity (CD226)31.