HLA B27 Test (Human Leucocyte Antigen B27) |#MTP|

Human leukocyte antigen HLA-B27 is a MHC (major histocompatibility complex) class I surface antigen encoded by the B locus on chromosome 6 and presents antigenic peptides (derived from self and non-self antigens) to T cells. HLA-B27 is strongly associated with ankylosing spondylitis and other associated inflammatory diseases, such as psoriatic arthritis, inflammatory bowel disease, and reactive arthritis. HLA B27 is considered to be an important criterion for the classification of axial spondyloarthropathies & helps in establishing early diagnosis of ankylosing spondyloarthropathies before the development of irreversible deformities. HLA-B27 is present in approximately 89% of patients with ankylosing spondylitis, 79% of patients with Reiter syndrome, and 42% of patients with juvenile rheumatoid arthritis. However, it is not diagnostic for these disorders. Approximately 8% of the normal population carries the HLA-B27 antigen.

The HLA B27 test is a blood test used to detect the presence of the HLA B27 gene, which is associated with autoimmune disorders such as ankylosing spondylitis, reactive arthritis, and others. The HLA B27 test helps in diagnosing these conditions, particularly in individuals showing symptoms like joint pain or stiffness. The HLA B27 blood test can aid in early detection. 

Reasons for Undergoing the HLA B27 Test 

The HLA B27 test is a critical diagnostic tool for identifying various autoimmune and inflammatory disorders. Here are the key reasons why a healthcare provider may recommend undergoing the HLA B27 blood test:

• Diagnosing Autoimmune Disorders: The HLA B27 test is primarily used to diagnose conditions in the spondyloarthritis group, including ankylosing spondylitis, reactive arthritis, psoriatic arthritis, and arthritis associated with Crohn’s disease or ulcerative colitis.  
• Investigating Joint Pain or Swelling: When patients present with unexplained joint pain, stiffness, or swelling, particularly in the spine, neck, or chest, the HLA B27 test is often performed to determine if an autoimmune condition may be the underlying cause. 
• Transplant Compatibility: The HLA B27 blood test is also used in organ and bone marrow transplant settings. It helps ensure compatibility between donors and recipients to minimize the risk of transplant rejection. 
• Monitoring Disease Progression: For patients diagnosed with autoimmune or immune-mediated disorders linked to the HLA B27 gene, this test can help monitor the disease’s progression and guide treatment decisions. It is also helpful for assessing the effectiveness of ongoing therapies and determining potential complications. 
• Family History of Autoimmune Diseases: If a patient has a family history of autoimmune or inflammatory disorders, especially those linked to HLA B27, the test may be recommended as a preventive measure or to identify early signs of disease. 

List of Parameters Considered During the HLA B27 Test 

The HLA B27 blood test focuses on measuring a specific parameter to provide valuable insights into a person's health. It primarily measures for the presence or absence of the human leukocyte antigen B27 (HLA-B27) protein on the surface of white blood cells, which indicates if an individual has a greater likelihood of developing or having certain autoimmune disorders, like ankylosing spondylitis and reactive arthritis.  

By determining if someone has this antigen, through the HLA B27 test, healthcare providers can understand their risk for certain conditions and guide them toward more tests or treatments. Ultimately, the HLA B27 test is vital for detecting and managing autoimmune disorders early.