HLA-DO

HLA-DO is a protein that in humans is encoded by the HLA-DOA and HLA-DOB genes. HLA-DO is an intracellular heterodimer that plays a critical role in the presentation of antigens to the immune system. It is part of the Major Histocompatibility Complex (MHC) class II molecules, which are expressed in antigen-presenting cells (APCs).

Structure

HLA-DO is composed of two non-covalently associated subunits, alpha (DOA) and beta (DOB). The alpha chain is encoded by the HLA-DOA gene, while the beta chain is encoded by the HLA-DOB gene. Both genes are located within the MHC class II region on chromosome 6.

Function

HLA-DO functions as a negative regulator of the immune response. It inhibits the peptide loading of MHC class II molecules by blocking the binding of the invariant chain (Ii) and the HLA-DM molecule. This results in a reduced ability of the immune system to respond to foreign antigens.

Clinical significance

Alterations in the expression of HLA-DO have been associated with various autoimmune diseases, including rheumatoid arthritis and multiple sclerosis. Further research is needed to fully understand the role of HLA-DO in these conditions.

See also

• Major Histocompatibility Complex
• MHC class II
• Antigen-presenting cell
• Autoimmune disease