HLA-B27 (Human Leukocyte Antigen B27)

This is a test to determine whether you have human leukocyte antigen B27 (HLA-B27) on the surface of your cells. This test is sometimes ordered to help assess the likelihood of having an autoimmune disorder. It is a test often done when you have symptoms of chronic inflammation, pain, and stiffness in certain areas of your body, such as your back, neck, and chest, especially if you are male and the symptoms began in your early 30s.

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 (a mixture of types A, B, C, and D) present on the surface of his white blood cells (leukocytes) and other nucleated cells. While not as unique as a fingerprint, the presence or absence of each antigen creates a one-of-a-kind HLA combination for each person. (This is important when someone needs a bone marrow or organ transplant, as the donor's HLA antigens must match up with the recipient's.)

Human leukocyte antigen B27 (HLA-B27) has been associated with several autoimmune disorders. The most common of these disorders is ankylosing spondylitis (AS). Approximately 90% of patients with AS carry HLA-B27. Other autoimmune disorders that have an association with the presence of B-27 are juvenile rheumatoid arthritis (80% of patients) and Reiter's syndrome (reactive arthritis; 50-80% of patients). HLA-B27 is also present in 50% of patients with inflammatory bowel disease with spondylitis and psoriasis vulgaris with spondylitis. While HLA-B27 has not been established as a cause of these conditions, there is a higher prevalence of this antigen in those affected.

PREPARATION FOR TEST

A blood sample is obtained by inserting a needle into a vein in the arm.

NORMAL FINDINGS

Negative

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.