**Background of HLA-DQA2 Antibodies**
HLA-DQA2. a gene within the human leukocyte antigen (HLA) complex on chromosome 6p21.3. encodes the α-chain of the HLA-DQ heterodimer, a key component of MHC class II molecules. These molecules present exogenous antigens to CD4+ T-cells, critical for adaptive immune responses. Unlike HLA-DQA1. which pairs with HLA-DQB1 to form the canonical HLA-DQ molecule, HLA-DQA2 exhibits limited polymorphism and lower expression. However, HLA-DQA2 can form non-canonical DQ heterodimers (e.g., with DQB2), though their functional roles remain less understood.
Antibodies targeting HLA-DQA2 are primarily studied in autoimmune diseases and transplantation. In autoimmune contexts, such as celiac disease or rheumatoid arthritis, anti-HLA-DQA2 antibodies may arise due to molecular mimicry or epitope spreading, contributing to tissue damage. In transplantation, preformed or de novo HLA-DQA2 antibodies are associated with graft rejection, as they may recognize donor-specific HLA antigens, triggering immune-mediated injury.
Detection methods include solid-phase assays (e.g., Luminex-based single-antigen beads) and cell-based crossmatches. While HLA-DQA2 antibodies are less frequently characterized than those against HLA-DQ/DR/DP, emerging evidence highlights their clinical relevance, particularly in sensitized patients or rare HLA haplotypes. Research continues to clarify their pathogenicity and diagnostic utility in precision medicine.