Furthermore, we found significant downregulation of most of HLA class II genes (HLA-DRB5, HLA-DQB1 and HLA-DQA2, etc.)in B cells from COVID-19 patients (Supplementary Fig. 7d), especially in the severe and acute necrotizing encephalopathy groups (Fig. 5i), indicating dysregulated crosstalk between adaptive immune cells. Here, HLA-DRB5 is linked to COVID-19.