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.
Drawn from a vein
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
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
C-reactive protein
C-reactive protein (CRP) is produced by the liver. The level of CRP rises when there is inflammation in the body. It is one of a group of proteins,...
ImageRead Article Now Book Mark Article - Erythrocyte sedimentation rate (ESR)
ESR
ESR stands for erythrocyte sedimentation rate. It is commonly called a "sed rate. "It is a test that indirectly measures the level of certain protei...
ImageRead Article Now Book Mark Article - Rheumatoid factor
Rheumatoid factor
Rheumatoid factor (RF) is a blood test that measures the amount of the RF antibody in the blood.
ImageRead Article Now Book Mark Article - X-rays
X-rays
X-rays are a type of electromagnetic radiation, just like visible light. An x-ray machine sends individual x-ray waves through the body. The images...
ImageRead Article Now Book Mark Article
HLA testing is also used to match donated tissue with a person's tissue who is getting an organ transplant. For example, it may be done when a person needs a kidney transplant or bone marrow transplant.
HLA testing
A histocompatibility antigen blood test looks at proteins called human leukocyte antigens (HLAs). These are found on the surface of almost all cells...
Kidney transplant
A kidney transplant is surgery to place a healthy kidney into a person with kidney failure.
Bone marrow transplant
A bone marrow transplant is a procedure to replace damaged or diseased bone marrow with healthy bone marrow stem cells. Bone marrow is the soft, fatt...
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.
Autoimmune disorders
An autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 autoimmune d...
A positive result can help your provider make a diagnosis of a form of arthritis called spondyloarthritis. This kind of arthritis includes the following disorders:
- Ankylosing spondylitis
Ankylosing spondylitis
Ankylosing spondylitis (AS) is a chronic form of arthritis. It mostly affects the bones and joints at the base of the spine where it connects with t...
ImageRead Article Now Book Mark Article - Arthritis related to Crohn disease or ulcerative colitis
Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
ImageRead Article Now Book Mark ArticleUlcerative colitis
Ulcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...
ImageRead Article Now Book Mark Article - Psoriatic arthritis (arthritis associated with psoriasis)
Psoriatic arthritis
Psoriatic arthritis is a joint problem (arthritis) that often occurs with a skin condition called psoriasis.
ImageRead Article Now Book Mark Article - Reactive arthritis
Reactive arthritis
Reactive arthritis is a type of arthritis that follows an infection. It may also cause inflammation of the eyes, skin and urinary and genital system...
ImageRead Article Now Book Mark Article - Sacroiliitis (inflammation of the sacroiliac joint)
- Uveitis
Uveitis
Uveitis is swelling and inflammation of the uvea. The uvea is the middle layer of the wall of the eye. The uvea supplies blood for the iris at the ...
ImageRead Article Now Book Mark Article
If you have symptoms or signs of spondyloarthritis, a positive HLA-B27 test may help confirm the diagnosis. However, HLA-B27 is found in some healthy people and does not always mean you have a disease.
Risks
Risks from having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
Lightheaded
Dizziness is a term that is often used to describe 2 different symptoms: lightheadedness and vertigo. Lightheadedness is a feeling that you might fai...
ImageRead Article Now Book Mark Article - Hematoma (blood accumulating under the skin)
Hematoma
A bruise is an area of skin discoloration. A bruise occurs when small blood vessels break and leak their contents into the soft tissue beneath the s...
ImageRead Article Now Book Mark Article - Infection (a slight risk any time the skin is broken)
Reviewed By
Diane M. Horowitz, MD, Rheumatology and Internal Medicine, Northwell Health, Great Neck, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Kumanovics A, Lazar-Molnar E, Delgado JC. The major histocompatibility complex and disease. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 51.
Inman RD, Rahman P. Spondyloarthritis. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 244.
Inman RD, Fitzgerald G. Classification and epidemiology of spondyloarthritis. In: Firestein GS, McInnes IB, Koretzky GA, Mikuls TR, Neogi T, O'Dell JR, eds. Firestein & Kelley's Textbook of Rheumatology. 12th ed. Philadelphia, PA: Elsevier; 2025:chap 75.