Dear sir/madam , Being HLA B27 positive does not mean that you have a disease. Yes being HLA B27 positive means that you a little more prone to certain diseases like Ankylosing spondylitis
..etc. There is nothing you can do to prevent such diseases. There is no scientific reference that you will get any of these diseases for sure since you are HLA B27 positive.So there is no need to panic.
Kindly find out why this test was done for you from the treating doctor. If you are having symptoms of joint pains
,skin lesions then you should get it worked up properly from a rheumatologist
Hope you find my answer useful . Take care.