Human leukocyte antigen

Human leukocyte antigen (HLA) is a group of proteins that are found on the surface of white blood cells. These proteins play a crucial role in the immune system's ability to distinguish between self cells and non-self cells. The HLA system is the human version of the major histocompatibility complex (MHC), which is found in all vertebrates.

Function

HLA proteins are responsible for presenting antigens to the immune system. When a foreign substance enters the body, these proteins bind to fragments of the substance and present them on the surface of the cell. This allows the immune system to recognize the substance as foreign and mount an immune response.

Types

There are three classes of HLA proteins: HLA class I, HLA class II, and HLA class III. HLA class I proteins are found on all nucleated cells and are involved in the presentation of endogenous antigens. HLA class II proteins are found on antigen-presenting cells and are involved in the presentation of exogenous antigens. HLA class III proteins are involved in the inflammatory response.

Role in disease

Certain HLA types are associated with an increased risk of developing specific diseases. For example, HLA-B27 is associated with an increased risk of developing ankylosing spondylitis, and HLA-DQ2 and HLA-DQ8 are associated with an increased risk of developing celiac disease.

Transplantation

HLA matching is a crucial part of organ and bone marrow transplantation. The closer the HLA match between the donor and the recipient, the lower the risk of graft-versus-host disease and organ rejection.

See also

• Antigen presentation
• Major histocompatibility complex
• Ankylosing spondylitis
• Celiac disease
• Graft-versus-host disease

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  Top-down view of DR beta 1
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  Illustration of DQ molecule
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  Expression of MHC molecules