Last but not least, HLA-DRB1 alleles could play a role in determining immunogenicity to infliximab in IBD, especially with the presence of arginine at position 74, as well as the absence of glutamate at position 71, in the peptide-ligating site of the HLA-DRB1 [15]. This evidence concerns the gene HLA-DRB1 and inflammatory bowel disease.