The mRNA expression of genes affiliated with Type I diabetes, such as major histocompatibility complex class I and II, CD80 and CD28 molecules, interferon gamma (IFNγ), interleukin 1 (IL-1), and tumor necrosis factor alpha/beta (TNF), were all down-regulated in opioid-exposed ccRCC tumors compared to non-exposed ccRCC specimens. This evidence concerns the gene CD80 and type 1 diabetes mellitus.