At a Glance
Why Get Tested?
When to Get Tested?
When you have symptoms of chronic inflammation, pain, and stiffness in certain areas of your body, such as your back, neck, and chest, or the interior portion of your eyes uveitis, especially if you are male and the symptoms began between late teens and your early 30s
A blood sample taken from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
HLA-B27 is a particular antigen found in certain people and the gene that codes for its production. It is one of many human leucocyte antigens (HLA). Human leucocyte antigens are a group of proteins that help the body's immune system identify its own cells and distinguish between "self" and "non-self." Everyone has an inherited combination of HLA genes that code for the antigens present on the surface of white blood cells (leucocytes) and other cells that contain a nucleus. While not as unique as a fingerprint, the presence or absence of each antigen creates a distinctive HLA combination for each person. This test determines the presence or absence of human leucocyte antigen B27 (HLA-B27) on the surface of a person's white blood cells.
HLA-B27 is found in about 8% of the UK population. Its presence has been associated with several autoimmune disorders. The most common of these disorders is ankylosing spondylitis (AS). In the UK approximately 95% of those with AS are positive for HLA-B27. Other disorders that have an association with the presence of HLA-B27 include juvenile rheumatoid arthritis (JRA), reactive arthritis (of which one subset is Reiter syndrome), and isolated acute anterior uveitis. Though the presence of HLA-B27 supports the diagnosis of these conditions, the relationship between HLA-B27 and the mechanism by which the diseases occur remains to be determined.
HLA-B27 may also be present in people with spondylitis associated with inflammatory bowel disease and psoriatic arthritis. While HLA-B27 has not been established as a cause of these disorders, there is a higher prevalence of the antigen in those affected.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.