HLA-B27

HLA-B27 is a specific allele of the HLA-B gene. HLA-B is part of the HLA class I heavy chain paralogues. This class I molecule is a heterodimer consisting of a heavy chain and a light chain (beta-2 microglobulin). The heavy chain is anchored in the membrane. Class I molecules play a central role in the immune system by presenting peptides derived from the endoplasmic reticulum lumen. They are expressed in nearly all cells.

Function

The primary function of HLA-B27 is to bind peptides derived from intracellular proteins and present them to CD8+ T cells, a type of white blood cell that plays a key role in the body's immune response. This process is crucial for the immune system's ability to recognize and destroy cells that are infected with viruses or other pathogens.

Association with disease

HLA-B27 is strongly associated with ankylosing spondylitis, a chronic inflammatory disease that primarily affects the spine and sacroiliac joints. Other diseases associated with this allele include reactive arthritis, psoriatic arthritis, and inflammatory bowel disease.

Testing

Testing for the presence of HLA-B27 is often performed in individuals with symptoms suggestive of an autoimmune disease, particularly those affecting the joints or spine. The test is typically performed using a blood sample.

See also

• Human leukocyte antigen
• Major histocompatibility complex
• Autoimmune disease