Analysis of a publicly available single-cell RNA sequencing (scRNAseq) dataset on nasopharyngeal samples (32) allowed identification of MAIT cells in the upper respiratory tract of COVID-19 patients and healthy control subjects using a combination of MAIT cell–defining transcripts (KLRB1, SLC4A10, IL7R, and DPP4) (Fig. 1E). The gene discussed is DPP4; the disease is COVID-19.