Human Leukocyte Antigen B27
What is HLA-B27?
HLA B-27, also called Human leukocyte antigen B-27, is a blood test indicated to look for a protein (HLA B-27), present on the surface of white blood cells. Presence of HLA B-27 may indicate a possibility of autoimmune disease, where the guarding cells (WBC) attacks own cells.
This test is done if one experiences symptoms of arthritis such as chronic joint pain, stiffness, and inflammation in the lower back. It may also be advised in case of inflammation of the eyes, especially in males.
People with HLA B-27 have increased chances of developing autoimmune diseases like rheumatoid arthritis and reactive arthritis. B-27 is also said to be linked with inflammatory bowel disease and other chronic conditions.
Why is HLA-B27 done?
The HLA B-27, PCR test is done:
In case of symptoms of arthritis such as chronic joint pain, stiffness, and inflammation in the lower back, hips, neck, and chest
In case of Uveitis (painful inflammation of eyes) especially in males where the symptoms started at the age of early 30s.
What does HLA-B27 Measure?
HLA B-27 test determines the presence or absence of human leukocyte antigen which is present on the surface of white blood cells. The HLA B-27 also refers to the gene which codes for the HLA B-27 protein.
HLA B-27 are proteins that help the immune system to differentiate the body’s own cells from other foreign cells. Every person has an inherited combination of HLA genes which codes for many antigens that are present on the surfaces of their cells. This HLA combination is distinctive for each person and is based on the presence or absence of each antigen.
People with HLA B-27 have increased chances of developing autoimmune diseases like ankylosing spondylitis, rheumatoid arthritis, reactive arthritis, and isolated acute anterior uveitis. HLA B-27 is also said to be linked with inflammatory bowel disease and other chronic conditions.
Interpreting HLA-B27 results
No expression of HLA B-27
Grey zone (within 10 channels of cutoff)
Expression of HLA B-27 detected
Anti-HLA-B27 antibody cross-reacts with several other antigens of HLA-B group specially HLA-B7 leading to false-positive results*