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HLA-B27

Also known as: HLA-B27 Antigen; B27
Formal name: Human Leukocyte Antigen B27
Related tests: ESR; CRP; RF; HLA Testing

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 the interior portion of your eyes (uveitis), especially if you are male and the symptoms began in your early 30s

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

HLA-B27 refers to a specific antigen found in certain people and the gene that codes for the production of that antigen. It is one of many human leukocyte antigens (HLA). Human leukocyte antigens are a group of proteins that help the body's immune system identify its own cells and distinguish between "self" and "nonself." Everyone has an inherited combination of HLA genes that code for the antigens present on the surface of his or her white blood cells (leukocytes) 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 leukocyte antigen B27 (HLA-B27) on the surface of a person's white blood cells.

HLA-B27 is found in about 5-10% of the U.S. population. Its presence has been associated with several autoimmune disorders. The most common of these disorders is ankylosing spondylitis (AS). Approximately 90% 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 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 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.

The Test

How is it used?

The HLA-B27 test is primarily ordered to help strengthen or confirm a suspected diagnosis of ankylosing spondylitis (AS), reactive arthritis, juvenile rheumatoid arthritis (JRA), or sometimes anterior uveitis. The HLA-B27 test is not a definitive test that can be used to diagnose or rule out a disorder. It is used as one piece of evidence in a constellation of signs, symptoms, and lab tests to support or rule out the diagnosis of certain autoimmune disorders, such as AS and reactive arthritis.

AS and reactive arthritis are both chronic, progressive conditions that occur more frequently in men than women. The first symptoms typically occur when a person is in their early 30's. Often, the initial symptoms of these autoimmune disorders are subtle and may take several years before characteristic degenerative changes to bones and joints are visible on X-rays.

  • Ankylosing spondylitis is characterized by pain, inflammation, and a gradual stiffening of the spine, neck and chest.
  • Reactive arthritis is a group of symptoms that includes inflammation of the joints, urethra, eyes, and skin lesions.
  • Juvenile rheumatoid arthritis is a form of arthritis that occurs in children.
  • Anterior uveitis is associated with recurring inflammation of the structures of one or both eyes.

The HLA-B27 test may be ordered as part of a group of tests used to diagnose and evaluate conditions causing arthritis-like chronic joint pain, stiffness, and inflammation. This group of tests may include an RF (rheumatoid factor) with either an ESR (erythrocyte sedimentation rate) or a CRP (C-Reactive protein). HLA-B27 is sometimes ordered to help evaluate someone with recurrent uveitis that is not caused by a recognizable disease process.

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When is it ordered?

An HLA-B27 test may be ordered when a person has acute or chronic pain and inflammation in the spine, neck, chest, eyes, and/or joints, and the doctor suspects an autoimmune disorder that is associated with the presence of HLA-B27. Doctors frequently must rely on their clinical findings and the HLA-B27 test result when diagnosing ankylosing spondylitis, and other HLA-B27-related disorders, because the characteristic changes to the bones may not be detectable for several years. Under these circumstances, HLA-B27 is not diagnostic but adds additional information, increasing or decreasing the likelihood that the patient has ankylosing spondylitis. An HLA-B27 may also be ordered when someone has recurrent uveitis.

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What does the test result mean?

If a person is positive for HLA-B27 and has symptoms such as chronic pain, inflammation, and/ or degenerative changes to his bones (as seen on X-ray), then it supports a diagnosis of ankylosing spondylitis, reactive arthritis, or another autoimmune disorder that is associated with the presence of HLA-B27. This is especially true if the person is young, male, and if he experienced his first symptoms before the age of 40.

If HLA-B27 is negative, then the association is not there. This does not, however, mean that the person does not have the suspected condition, as a certain percentage of people with each disorder will be HLA-B27 negative.

  • Ankylosing spondylitis: about 90% are HLA-B27 positive
  • Juvenile rheumatoid arthritis (JRA): about 80% are HLA-B27 positive
  • Reactive arthritis: about 60-85% are HLA-B27 positive
  • Isolated acute anterior uveitis: about 40-70% are HLA-B27 positive

Whether or not HLA antigens will be present is genetically determined. Their production is controlled by genes that are passed from parents to children. If a person has a close family member with an HLA-B27 related disease that affects the joints of the spine (AS or other related condition) and is positive for the HLA-B27 antigen, then that person is at an increased risk of developing a similar disease.

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Is there anything else I should know?

Though the diseases associated with HLA-B27 occur more frequently in men, women can also be affected. However, the signs and symptoms related to the diseases can often be milder in women.

With new genetic testing methods, it is now possible to separate HLA-B27 into subtypes. So far, about fifteen different subtypes have been identified. The most common in the U.S. are HLA B27*05 and HLA B27*02. How the presence of these specific subtypes affects the likelihood of developing an autoimmune disease is not yet known.

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Common Questions

1.  What causes the autoimmune disorders associated with HLA-B27?

In most cases, the cause is not known. However, in some cases of reactive arthritis, there is an association between a previous infection by a microorganism, such as Chlamydia, Campylobacter, Salmonella, Ureaplasma, or Yersinia, and the onset of the disease. It is thought that similarities between the HLA-B27 antigen and the antigens found on the surface of the microorganisms trigger the immune system to fight both the microorganism and the person's own tissues, launching the autoimmune disorder after the resolution of the infection.

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2.  Can I be tested for HLA-B27 in my doctor's office?

HLA-B27 testing requires specialized equipment and expertise to perform. It is not typically performed in a doctor's office and is not offered by every laboratory. In most cases, your blood sample will be sent to a reference laboratory.

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3.  Should everyone have an HLA-B27 test done?

Routine testing of the general public is not recommended. Usually only those with symptoms will be tested. A positive HLA-B27 in a person who does not have symptoms or a family history of HLA-B27-associated disease is not clinically significant. It does not help predict the likelihood of developing an autoimmune disease. Occasionally a family member of a person who is positive for HLA-B27 and has an autoimmune disorder may be tested, but the test result cannot be used to predict whether the tested person will develop a related autoimmune disease.

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Article Sources

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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.

Sources Used in Current Review

Dugdale, D. (Updated 2009 May 21). HLA-B27 antigen. MedlinePlus Medical Encyclopedia [On-line information] Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003551.htm. Accessed October 2010.

Mayo Clinic Staff (2009 February 3). Ankylosing spondylitis. MayoClinic.com [On-line information] Available online at http://www.mayoclinic.com/print/ankylosing-spondylitis/DS00483/DSECTION=all&METHOD=print through http://www.mayoclinic.com. Accessed October 2010.

Brent, L. and Kalagate, R. (Updated 2010 May 6). Ankylosing Spondylitis and Undifferentiated Spondyloarthropathy. eMedicine On-line information] Available online at http://emedicine.medscape.com/article/332945-overview through http://emedicine.medscape.com. Accessed October 2010.

Altman, R. (Revised 2008 February). Seronegative Spondyloarthropathies (Seronegative Spondyloarthritides). Merck Manual for Healthcare Professionals [On-line information] Available online at http://www.merck.com/mmpe/sec04/ch034/ch034d.html?qt=HLA-B27&alt=sh through http://www.merck.com. Accessed October 2010.

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 544-545.

Waheed N. HLA-B27 associated uveitis. Ocular Immunology and Uveitis Foundations, ©2008. Available online at http://www.uveitis.org/medical/articles/case/hlab27.html through http://www.uveitis.org. Accessed Nov 2010.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL eds (2005). Harrison's Principles of Internal Medicine, 16th Edition, McGraw Hill, Pp 1936-1937, 1993-1997.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Ankylosing spondylitis. Hendrick Health System, AccessMed Online Health Information Library [On-line information]. Available online at http://www.ehendrick.org/healthy/ through http://www.ehendrick.org.

HLA-B27. ARUP's Guide to Clinical Laboratory Testing (CLT) [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a287.htm#1195370 through http://www.aruplab.com.

Diagnosis, Symptoms, and Treatment. Spondylitis Association of America [On-line information]. Available online at http://www.spondylitis.org/html/htmlpages.asp?load=diagnosis_what.htm through http://www.spondylitis.org.

Mayo Clinic Staff (2003 June 05). Ankylosing spondylitis. MayoClinic.com, Diseases and Conditions [On-line information. Available online at http://www.mayoclinic.com/invoke.cfm?id=DS00483 through http://www.mayoclinic.com.

Kovacs, B. (2001 November 29, Updated). Reiter's syndrome. MEDLINEplus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000440.htm.

Milone, M. (2001 November 19, Updated). Histocompatibility antigens. MEDLINEplus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003550.htm.

Milone, M. (2001 December 5, Updated). HLA-B27 antigen. MEDLINEplus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003551.htm.

(2003 May 21, Updated). Spondylitis: Frequently Asked Questions. Spondylitis Association of America [On-line information]. Available online at http://www.spondylitis.org/about/faq.aspx through http://www.spondylitis.org.

(2003 June 19, Updated). Reactive Arthritis/Reiter's Syndrome (ReA), Diagnosis. Spondylitis Association of America [On-line information]. Available online at http://www.spondylitis.org/about/reactive/diagnosis.aspx through http://www.spondylitis.org.

Agrawal, S. (2003 August 15). Immunophenotyping using flow cytometry. Express Healthcare Management [On-line Newspaper, India]. Available online at http://www.expresshealthcaremgmt.com/labwatch/lab6.shtml through http://www.expresshealthcaremgmt.com.

Waheed, N. (1998). HLA-B27 Associated Uveitis. Massachusetts Eye & Ear Infirmary, Ocular Immunology & Uveitis Service [On-line information]. Available online at http://www.uveitis.org/Enhanced/MD_info/md_hlab27.htm through http://www.uveitis.org.

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp. 544-545.

(© 2007). Ankylosing Spondylitis (AS) Diagnosis. Spondylitis Association of America [On-line information]. Available online at http://www.spondylitis.org/about/as_diag.aspx through http://www.spondylitis.org. Accessed on 9/09/07.

Alexander, D. (2007 May 29, Updated). HLA-B27 antigen. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003551.htm. Accessed on 9/09/07.

Thjodleifsson, B. et. al.(2007 July 30). Evidence of a Common Genetic Background for Ankylosing Spondylitis and Inflammatory Bowel Disease. American College of Rheumatology from Arthritis & Rheumatism 2007; (DOI:10.1002/art.22812) [On-line journal article]. Available online at http://www.rheumatology.org/press/2007/0730ankylosing.asp through http://www.rheumatology.org. Accessed on 9/09/07.

(© 2007). Ankylosing Spondylitis. American College of Rheumatology [On-line information]. Available online at http://www.rheumatology.org/public/factsheets/as.asp?aud=pat through http://www.rheumatology.org. Accessed on 9/9/07.

Waheed, N. (© 1996-2006). HLA-B27 Associated Uveitis. The Ocular Immunology and Uveitis Foundation [On-line information]. Available online at http://www.uveitis.org/medical/articles/case/hlab27.html through http://www.uveitis.org. Accessed on 9/09/07.