At a Glance
Why Get Tested?
To determine whether you have human leukocyte antigen B27 (HLA-B27) on the surface of your cells; to help assess the likelihood that you have an autoimmune disorder associated with the presence of HLA-B27
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 eyes, especially if you are male and the symptoms began in your early 30s
A blood sample drawn from a vein in your arm
The Test Sample
What is being tested?
This test detects the presence or absence of human leukocyte antigen B27 (HLA-B27) on the surface of white blood cells in a blood sample. Human leukocyte antigens (HLA) are a group of proteins that help the body's immune system to identify its own cells and to distinguish between 'self' and 'nonself'. Everyone has an inherited combination of HLA antigens present on the surface of his or her white blood cells (leukocytes) and other nucleated (containing a nucleus) cells.
These HLA antigens are divided into types: Class I (A, B, C) and Class II (DR, DP, DQ). While not as unique as a fingerprint, the presence or absence of each antigen creates a distinctive HLA combination for each person.
HLA-B27 is found in about 5-10% of the Australian population. Its presence has been associated with several autoimmune disorders. The most common of these disorders is ankylosing spondylitis (AS). Approximately 90% of patients with AS are positive for HLA-B27. Other disorders that have an association with the presence of HLA-B27 include:
- Juvenile rheumatoid arthritis (JRA), in which the later onset variant is associated with HLA-B27.
- Reactive arthritis (also known as Reiter's syndrome): about 50-80% of patients are positive.
- Isolated acute anterior uveitis: about 40-70% of cases are positive.
HLA-B27 may also be present in patients with inflammatory bowel disease and with a range of other chronic conditions. While HLA-B27 has not been established as a cause of these disorders, there is a higher prevalence of this 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.
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.