What is the HLA-B27 test?
The human leukocyte antigen B27 blood test is also known as the HLA-B27 test.
The HLA-B27 test is used to identify a specific protein in white blood cells that can be a sign of autoimmune disease.
This test is one step in the process of diagnosing a possible autoimmune disorder.
Human leukocyte antigen B27 (HLA-B27) is a protein located on the surface of white blood cells. An HLA-B27 test is a blood test that identifies HLA-B27 proteins.
Human leukocyte antigens (HLA) are proteins commonly found on white blood cells. These antigens help your immune system identify the differences between healthy body tissue and foreign substances that can cause infection.
Although most HLAs protect your body from damage, HLA-B27 is a specific type of protein that contributes to immune system dysfunction. The presence of HLA-B27 in your white blood cells can cause your immune system to attack cells that would otherwise be healthy. When this occurs, it can result in an autoimmune disease or an immune-mediated disease, such as juvenile rheumatoid arthritis or ankylosing spondylitis.
How is the HLA-B27 test used?
Using the HLA-B27 test result for disease monitoring:
The presence of HLA-B27 is associated with certain autoimmune and immune-mediated diseases, including:
ankylosing spondylitis, which causes inflammation of the bones of the spine
reactive arthritis, which causes inflammation of the joints, urethra, and eyes, and sometimes skin lesions
Juvenile rheumatoid arthritis
anterior uveitis, which causes swelling and irritation in the middle layer of the eye
A doctor may order the HLA-B27 test to monitor the progression of these and other autoimmune diseases.
Diagnostic uses of the HLA-B27 test:
For people with specific symptoms, the HLA-B27 test can be used in conjunction with other blood, urine, or imaging tests to confirm the diagnosis of an autoimmune disease. Symptoms that may prompt a doctor to order the test include:
bread set
stiffness or swelling of the spine, neck, or chest
inflammation of the joints or urethra accompanied by skin lesions
recurrent inflammation in the eye
Your doctor may order HLA antigen tests, including tests for HLA-B27, when you have a kidney or bone marrow transplant. These tests can be used to ensure a proper match between you and a donor.
How is the HLA-B27 test result interpreted?
A negative test indicates the absence of HLA-B27 in your blood.
However, if the test is negative, it does not mean that you do not have an autoimmune disorder. In making a final diagnosis, your doctor will consider all the test results along with your symptoms. Sometimes people with autoimmune disorders do not have HLA-B27 in their white blood cells.
If the test is positive, this means that HLA-B27 is present in your blood. Although a positive result can be cause for concern, the presence of the antigen does not always mean that an autoimmune disorder will develop. The diagnosis of an autoimmune disorder should be based on your symptoms and the results of all blood tests and diagnostic tests.
By Dr. Mehul Dave