Liu Y, Zhu P, Wang W, et al. - Researchers investigated the antiviral potential of mucosal‐associated invariant T (MAIT) cells as well as assessed their dynamic alterations and regulating factors during chronic HBV infection. This study involved blood samples from 257 chronic HBV‐infected patients as well as non‐tumor liver specimens from 58 HBV‐infected hepatocellular carcinoma patients. Integrating cell culture experiments and human data, a strong cytotoxicity of MAIT cells against HBV‐transfected hepatocytes was evident in a MR1 (MHC class I‐related protein 1)‐dependent way. In this study, not only MR1‐dependent anti‐HBV potential of MAIT cells was shown but also conjugated bilirubin was exposed as a major factor dysregulating its frequency as well as function in chronic HBV‐infected patients, indicating a new treatment target for MAIT cell‐based immunity against chronic HBV infection.