LAB TEST
HLA-B27 antigen
HLA-B27 is a blood test to look for a protein that is found on the surface of white blood cells. The protein is called human leukocyte antigen B27 (HLA-B27). Human leukocyte antigens (HLAs) are proteins that help the body's immune system tell the difference between its own cells and foreign, harmful substances. They are made from instructions by inherited genes.
How the Test is Performed
A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.
How to Prepare for the Test
No special steps are needed to prepare for the test.
How the Test will Feel
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the Test is Performed
Your health care provider may order this test to help determine the cause of joint pain, stiffness, or swelling. The test may be done along with other tests, including: Anti-cyclic citrullinated peptide (CCP) antibody C-reactive protein Erythrocyte sedimentation rate ( ESR ) Rheumatoid factor X-rays HLA testing is…
Normal Results
A normal (negative) result means HLA-B27 is absent.
What Abnormal Results Mean
A positive test means HLA-B27 is present. It suggests a greater-than-average risk for developing or having certain autoimmune disorders. An autoimmune disorder is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. A positive result can help your provider make a…
Risks
Risks from having blood drawn are slight, but may include: Excessive bleeding Fainting or feeling lightheaded Hematoma (blood accumulating under the skin) Infection (a slight risk any time the skin is broken)
References
Bray R, Sullivan HC, Krummey S, Gebel HM. Human leukocyte antigen: the major histocompatibility complex of humans. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods . 24th ed. Philadelphia, PA: Elsevier; 2022:chap 50. Lienesch DW. Spondyloarthritis. In: Wing EJ,…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 30/04/2023).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.