HLA-B27


HLA-B27

An antigen or protein marker on cells that may indicate ankylosing spondylitis.Mentioned in: Ankylosing Spondylitis

Human Leukocyte Antigen B27

Synonym/acronym: HLA-B27.

Common use

To assist in diagnosing juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and Reiter’s syndrome.

Specimen

Whole blood (5 mL) collected in a green-top (heparin) or a yellow-top (acid-citrate-dextrose [ACD]) tube.

Normal findings

(Method: Flow cytometry) Negative (indicating absence of the antigen).

Description

The human leukocyte antigens (HLAs) are gene products of the major histocompatibility complex, derived from their respective loci on the short arm of chromosome 6. There are three general groups, HLA-A, HLA-B, and HLA-DR. Each group contains many different proteins. HLA-B27 is an allele (one of two or more genes for an inheritable trait that occupy the same location on each chromosome, paternal and maternal) of the HLA-B locus. There are a number of HLA-B27 subtypes, not all of which are associated with disease. The antigens are present on the surface of nucleated tissue cells as well as on white blood cells. HLA testing is used in determining histocompatibility for organ and tissue transplantation. Another application for HLA testing is in paternity investigations. The presence of HLA-B27 is associated with several specific autoimmune conditions including ankylosing spondylitis, rheumatoid arthritis, psoriatic arthritis, undifferentiated oligoarthritis, uveitis, and inflammatory bowel disease. Although less than 10% of the population are carriers of HLA B-27, 20% of carriers will develop an autoimmune condition.

This procedure is contraindicated for

    N/A

Indications

  • Assist in diagnosing ankylosing spondylitis and Reiter’s syndrome (reactive arthritis)
  • Determine compatibility for organ and tissue transplantation

Potential diagnosis

Positive findings in:

  • Ankylosing spondylitis
  • Inflammatory bowel disease
  • Juvenile rheumatoid arthritis
  • Psoriatic arthritis
  • Reiter’s syndrome
  • Sacroiliitis
  • Uveitis

Critical findings

    N/A

Interfering factors

  • The specimen should be stored at room temperature and should be received by the laboratory performing the assay within 24 hr of collection. It is highly recommended that the laboratory be contacted before specimen collection to avoid specimen rejection.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist with investigation of specific leukocyte disorders and determine compatibility for organ and tissue transplantation.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s immune system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Recognize anxiety related to test results, and be supportive of perceived loss of independence and fear of shortened life expectancy. These diseases can be moderately to severely debilitating, resulting in significant lifestyle changes. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Inform the patient that false-positive test results occur and that retesting may be required. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include ANA, CBC, CT spine, ESR, MRI musculoskeletal, radiography bone, and RF.
  • Refer to the Immune System table at the end of the book for related tests by body system.