For example, the hprt4-18 peptide from the human gut commensal Parabacteroides distasonis not only shares >50% homology with the insulin B-chain 9-23 sequence (insB:9-23), but also activates HLA-DQ8 CD4+ T cells from T1D patients in vitro [131]. This evidence concerns the gene CD4 and type 1 diabetes mellitus.