HLA-DQ8
HLA-DQ8 is a human leukocyte antigen (HLA) serotype within the HLA-DQ locus. HLA-DQ is part of the major histocompatibility complex (MHC) class II, which is crucial for the adaptive immune system. The MHC class II molecules present peptide fragments to T helper cells, initiating an immune response.
Specifically, HLA-DQ8 refers to a heterodimer formed by the DQ alpha 1 and DQ beta 1 chains. These chains are encoded by the HLA-DQA1 and HLA-DQB1 genes, respectively. The HLA-DQ8 serotype is typically associated with specific alleles of these genes, most commonly HLA-DQA1 03:01 and HLA-DQB1 03:02. However, other allele combinations can also lead to DQ8 serological reactivity.
Individuals inherit one HLA-DQA1 and one HLA-DQB1 allele from each parent, leading to a diverse range of possible HLA-DQ haplotypes. The specific HLA-DQ molecule an individual expresses influences their susceptibility or resistance to certain autoimmune diseases.
HLA-DQ8 is strongly associated with several autoimmune diseases, including:
- Type 1 Diabetes (T1D): HLA-DQ8 is considered a high-risk allele for T1D, particularly in certain populations.
- Celiac Disease: HLA-DQ8 is one of the two main HLA haplotypes associated with celiac disease, the other being HLA-DQ2.5.
- Dermatitis Herpetiformis: This skin manifestation of celiac disease is also associated with HLA-DQ8.
The association between HLA-DQ8 and these autoimmune diseases suggests that the HLA-DQ8 molecule is particularly efficient at presenting self-antigens to T cells, leading to an autoimmune response. The exact mechanisms by which HLA-DQ8 contributes to disease pathogenesis are still under investigation but involve peptide binding specificities and T cell activation.
Testing for HLA-DQ8 is often performed using serological methods or molecular techniques such as PCR-based HLA typing. Such testing is valuable in assessing an individual's risk for the associated autoimmune diseases, particularly in clinical settings where there is a strong suspicion of these conditions.