HLA-DQ4

DQ_Illustration.PNG

HLA-DQ4 is a human leukocyte antigen (HLA) serotype within the HLA-DQ (DQ) class II antigen family. The serotype is determined by the recognition of the β^4 chain of the DQ molecule. HLA-DQ4 is encoded by the HLA-DQB1*04 allele group and is associated with the DQA1*03 and DQA1*04 alleles.

Structure

HLA-DQ4 is a heterodimer composed of an α (alpha) chain and a β (beta) chain. The α chain is encoded by the HLA-DQA1 gene, and the β chain is encoded by the HLA-DQB1 gene. The specific combination of these chains forms the DQ4 molecule, which is expressed on the surface of antigen-presenting cells.

Function

The primary function of HLA-DQ4, like other HLA class II molecules, is to present peptide antigens to CD4+ T cells. This interaction is crucial for the activation of the adaptive immune response, enabling the body to recognize and respond to pathogens.

Serology

HLA-DQ4 serotyping is used to identify the presence of the DQ4 molecule on the surface of cells. This is important in the context of organ transplantation, autoimmune diseases, and disease association studies. The serotype is identified using specific antibodies that recognize the β^4 chain.

Disease Associations

HLA-DQ4 has been studied for its association with various diseases. Some of these associations include:

• Type 1 diabetes
• Celiac disease
• Rheumatoid arthritis

The presence of HLA-DQ4 can influence the susceptibility to these diseases, although the exact mechanisms are still under investigation.

Genetic Diversity

The HLA-DQB1*04 allele group exhibits genetic diversity, with several known subtypes. These subtypes can vary in their peptide-binding properties and their association with different diseases.

Clinical Relevance

Understanding the distribution and function of HLA-DQ4 is important in clinical settings, particularly in transplantation and autoimmune disease management. HLA typing, including DQ4 serotyping, is a critical component of histocompatibility testing.

See Also

• HLA-DQ
• HLA-DQ2
• HLA-DQ8
• HLA-DQA1
• HLA-DQB1
• Major histocompatibility complex