HLA-DQB1 antibodies target a specific component of the human leukocyte antigen (HLA) class II system, encoded by the HLA-DQB1 gene. HLA class II molecules, including HLA-DQ (composed of DQA and DQB chains), are expressed primarily on antigen-presenting cells and play a critical role in adaptive immunity by presenting exogenous antigens to CD4+ T cells. HLA-DQB1 exhibits high polymorphism, with numerous allelic variants linked to autoimmune diseases, transplant rejection, and infection susceptibility. Antibodies against HLA-DQB1 often arise from alloimmunization, such as through pregnancy, blood transfusions, or organ transplantation, but may also develop in autoimmune contexts. These antibodies can trigger immune-mediated damage, particularly in solid organ transplantation, where they are associated with antibody-mediated rejection (AMR) and graft failure. Clinically, HLA-DQB1 antibodies are screened pre-transplant to assess donor-recipient compatibility. Specific HLA-DQB1 alleles (e.g., *02. *03:02. *05:01) are strongly correlated with autoimmune conditions like type 1 diabetes, celiac disease, and multiple sclerosis, though their pathogenic mechanisms in autoimmunity remain under investigation. Detection methods include solid-phase assays (e.g., Luminex), which identify antibody specificity and strength. Research continues to explore their role in disease progression and tolerance induction strategies.