Because FAS expression is increased on MAIT cells in SLE (median MFI for HCs 756 AU [IQR 647–1474] vs median MFI for SLE 1879 AU [1786–4855]) (Fig. 2a), we speculate that apoptosis occurs in MAIT cells through activation-induced cell death. This evidence concerns the gene FAS and systemic lupus erythematosus.