HLA-DRB5 and influenza: Comparing transcriptomes between severe and moderate influenza illness, we observed that the most down-regulated transcripts were from genes coding for Major histocompatibility complex (MHC) class II (HLA-DRB5, HLA-DRA1, MHC class II alfa and beta chain, HLA-DRB1, HLA-DRB4, HLA-DRB3, HLA-DRB) (p <  0.0001).