HLA class II histocompatibility antigen, DQ beta 1 chain (HLA-DQB1*05:02) (HLA-DQB1*05:02)

HLA-DQB1*05:02 is a specific allele of the Human Leukocyte Antigen (HLA) class II beta chain, which forms a heterodimer with an alpha chain to create the HLA-DQ protein complex (UniProt: P01920). This complex is expressed on the surface of professional antigen-presenting cells, where its primary biological function is to bind exogenous peptides within its peptide-binding groove and present them to CD4+ T-helper cells (IMGT/HLA Database). This interaction is a critical step in the initiation of the adaptive immune response. HLA-DQB1*05:02 is highly significant in clinical medicine due to its strong genetic association with Muscle-Specific Kinase (MuSK) antibody-positive Myasthenia Gravis, an autoimmune neuromuscular disorder (Niks et al., 2007, PMID: 17606768). In these patients, the HLA-DQB1*05:02 molecule is thought to preferentially present MuSK-derived peptides, leading to the loss of self-tolerance and the production of pathogenic IgG4 autoantibodies (Stathopoulos et al., 2017, PMID: 28100595). While not a traditional target for small molecule inhibitors, the peptide-binding groove of this specific HLA allele represents a focal point for developing selective immunotherapies, such as peptide-based decoys or TCR-like antibodies, aimed at blocking the presentation of autoantigens without causing broad immunosuppression (Zisimopoulou et al., 2017). Additionally, this allele has been linked to other autoimmune conditions, such as bullous pemphigoid, highlighting its role in aberrant immune recognition (Fang et al., 2018). Therapeutic challenges include the high polymorphism of HLA genes and the need for extreme specificity to avoid off-target immune suppression.

Other names

MHC class II antigen DQB1*05:02HLA-DQ5.2HLA-DQB1*0502Major histocompatibility complex, class II, DQ beta 1

Presentation of autoantigenic peptides to CD4+ T cells; potential target for competitive peptide inhibition