Role of genetic variations on MHC class I antigen-processing genes in human cancer and viral-mediated diseases.

Cytotoxic T lymphocytes constantly monitor peptide-MHC class I complexes on the cell surface to eliminate transformed and virally infected cells expressing peptides derived from abnormal proteins. The generation of antigenic peptides and their loading on MHC class I molecules is a multistep process involving different molecules that constitute the so-called antigen processing and presentation machinery (APM). To avoid immune-mediated elimination, human tumors and pathogens have adopted different strategies including loss of MHC class I expression and dysregulation of APM genes and proteins. Here, we summarize recent knowledge on genetic variations in APM genes and their association with cancer development and viral-mediated diseases.