HLA-B21

HLA-B21 is a human leukocyte antigen serotype within HLA-B serotype group. The serotype is determined by the antibody recognition of antigen B21. This broad antigen group is a part of the HLA-B locus group which is a part of the larger Major Histocompatibility Complex (MHC) group. HLA-B21 is associated with certain diseases, including ankylosing spondylitis and Behcet's disease.

Structure and Function

HLA-B21 is a cell surface protein that plays a crucial role in the regulation of the immune system in humans. It is involved in the presentation of foreign peptides to the immune system. This antigen presentation is a key step in the immune response, leading to the activation of T cells, which then coordinate the body's immune response.

Disease Associations

HLA-B21 has been associated with several diseases. For example, it has been linked to an increased risk of ankylosing spondylitis, a type of arthritis that affects the spine. Additionally, it has been associated with Behcet's disease, a rare disorder that causes blood vessel inflammation throughout the body.

Genetic Diversity

HLA-B21 is highly polymorphic, which means it has many different forms. This high level of diversity is thought to be an evolutionary adaptation that allows the immune system to respond to a wide range of pathogens.

See Also

• HLA-B
• Major Histocompatibility Complex
• Ankylosing spondylitis
• Behcet's disease