In this regard, the recent identification of gut microbiome differences between DRB1*0402 (RA-resistant) and DRB1*0402 (RA-susceptible) HLA-transgenic mice [45] raises questions as to the microbiome of the transplanted lung, and whether the DR15+ lung might contain microbiota that promote a Th17 response to the immunogenic HLA-DR15-binding α1(V) peptides. Here, HLA-DRB1 is linked to rheumatoid arthritis.