The cause of type 1 diabetes remains unknown. Several studies using immunohistochemistry (IHC) have independently reported hyperexpression of human leukocyte antigen (HLA) class I on pancreatic islet cells in young patients with recent-onset type 1 diabetes. Investigators have therefore suggested that HLA hyperexpression may be an important first step in the development of type 1 diabetes. However, a new study challenges these findings .