We have previously shown that DNA methylation may mediate genetic risk of HLA-DRB1*15:01 variant in MS through changes in HLA-DRB1 gene expression.13 In addition, we have previously found that cigarette smoking not only alters blood DNA methylation in MS patients but also interacts with the disease in a smoking load-dependent manner.14 However, so far, little is known about the smoking-associated changes locally, in the primary exposed lung tissue of MS patients. This evidence concerns the gene HLA-DRB1 and myeloid sarcoma.