HLA-A3

HLA-A3 is a human leukocyte antigen serotype within HLA-A serotype group. The serotype is determined by the antibody recognition of α3 domain. HLA-A3 is a cell surface protein that plays a crucial role in the regulation of the immune system in humans. It 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).

Structure and Function

HLA-A3 is a cell surface receptor that presents peptides derived from the endoplasmic reticulum lumen. The peptides transported via the transporter associated with antigen processing (TAP) are loaded onto HLA-A3. The loaded HLA-A3 is then transported to the cell surface by exocytosis.

The HLA-A3 molecule is a heavy chain that is anchored in the membrane. It is associated with beta-2 microglobulin, which is not anchored. The heavy chain is approximately 45 kDa and its gene contains 8 exons. The alpha-1 and alpha-2 domains are responsible for peptide binding, while the alpha-3 domain interacts with the T-cell receptor.

Clinical Significance

HLA-A3 has been associated with a variety of diseases. It is linked to increased susceptibility to hepatitis C infection and progression to chronic hepatitis. It is also associated with a higher risk of developing autoimmune diseases such as rheumatoid arthritis and multiple sclerosis.

In organ transplantation, HLA-A3 mismatch is associated with a higher risk of graft rejection. Therefore, HLA-A3 matching is an important factor in organ transplantation.

See Also

• Human leukocyte antigen
• HLA-A
• Autoimmune diseases
• Organ transplantation

References

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