HLA-B27, or Human Leukocyte Antigen B27, is a class I surface antigen that is associated with certain inflammatory diseases, including ankylosing spondylitis. This disease is also referred to as Bekhterev's disease or Marie-Strumpell disease.
A simple blood test is performed to check for HLA-B27. Doctors typically test for this antigen when a patient is having joint pain issues or when matching kidneys or bone marrow. A positive test for HLA-B27 also suggests a higher risk for developing psoriatic arthritis, Reiter's syndrome, sacroiliitis, uveitis or arthritis related to Crohn's disease. Doctors and researchers stress that HLA-B27 in the blood does not necessarily mean that a disease is present, only that there is a higher risk of certain diseases.