CD8A and neoplasm: We also examined the expression of additional inhibitory receptors on tumor-infiltrating MAIT cells, and found that although the frequencies of CD39+ and TIGIT+ MAIT cells varied between individuals, they were generally higher in mucosal than in circulating MAIT cells, especially in the CD8+ MAIT cells (p < 0.05–0.01; Fig. 2a, b).