Human leukocyte antigen B27 is a marker antibody for rheumatoid arthritis with high specificity. It has diagnostic significance for early rheumatoid arthritis or rheumatoid arthritis with atypical clinical symptoms. Therefore, human white blood antigen B27 is generally used in clinical practice as an important test for the diagnosis of rheumatoid arthritis. There is also a close correlation between human leukocyte antigen B27 and ankylosing spondylitis. 90% of ankylosing spondylitis is positive for human leukocyte antigen B27, compared to 4%-7% of normal individuals, so it can also be an important test for the diagnosis of ankylosing spondylitis.