What is being tested?

This test detects characteristic changes (rearrangements) in specific genes in B-cells. This information can be helpful in diagnosing a B-cell lymphoma. For an explanation of gene rearrangement please see Common Questions - How common are B-cell gene rearrangements?

B-cells are a type of lymphocyte, a type of white blood cell (WBC) that produces antibodies in response to infections (viruses, bacteria or parasites) as well as other "foreign invaders" that the immune system wants to destroy. Like almost all cells in the human body, white blood cells contain DNA. They start out as stem cells and as they develop into mature cells they develop rearrangements in certain parts of their DNA called immunoglobulin genes. B-cell immunoglobulin genes rearrange themselves during the development of each cell so that each one can produce a unique immunoglobulin or antibody molecule. These rearrangements are normal. The antibodies produced by the B-cells collectively protect against many different kinds of infections. The final order in which the genes are rearranged is called a gene rearrangement profile. Within any normal population of B-cells, the cells and their gene rearrangement profiles are very diverse.

In a lymphoma, the B-cells in affected tissue (such as blood, bone marrow or lymph node) are identical and their gene rearrangement profiles are likewise identical. Lymphomas arise when an abnormal B-cell begins to produce numerous identical copies of itself (clones). The cloned cells grow and divide uncontrollably, crowding out normal cells.

A B-cell immunoglobulin gene rearrangement test evaluates the B-cells in a person's sample to determine whether the majority of B-cell rearrangement profiles are diverse or identical. This information, along with clinical signs and symptoms and results of other laboratory tests, can help clarify a person's diagnosis, or evaluate the persistence or recurrence of lymphoma.

According to the Australian Institute of Health and Welfare, about 5,700 new cases of non-Hodgkin lymphoma are diagnosed in Australia each year. The majority of non-Hodgkin lymphomas are B-cell lymphomas.

For additional details about B-cells and this testing, read more.

How is it used?

B-cell immunoglobulin gene rearrangement tests are used to help diagnose non-Hodgkin B-cell lymphomas and check for residual or recurrent disease after treatment.

Lymphomas arise when an abnormal B-cell begins to produce numerous identical copies of itself (clones). The cloned cells grow and divide uncontrollably, crowding out normal cells. There are many different types of B-cell lymphoma and each has different characteristics, prognosis, and therapy. Several classification systems have been used to describe them. The most recent is from the World Health Organization (for more on this, see the Lymphoma article).

Testing for B-cell lymphomas involves several types of tests:

• Full Blood Count (FBC) and a WBC differential to evaluate the number, types and maturity of white blood cells present in the blood. Results may reveal an increased number of lymphocytes and/or the presence of abnormal lymphocytes.
• Pathology evaluation of blood film, bone marrow, lymph node and/or other tissue biopsy samples. These samples are examined under a microscope by a specialist pathologist or scientist.
• If indicated, immunophenotyping is performed on blood, bone marrow, or other tissue (e.g., enlarged lymph node, tumour) using a method such as flow cytometry or immunohistochemistry. This test detects the presence or absence of certain markers on the outer membrane of the cells or inside the cells. These commonly used markers are called clusters of differentiation (CD) and are listed numerically. Patterns of antigens (presence or absence) can provide information as to whether the B-cells are clones (monoclonal) and can further help classify a B-cell lymphoma.

A proliferation of B-cells can be benign or malignant. If, at this point, there is still no conclusion whether a person has a benign or malignant lymphocyte population, B-cell immunoglobulin gene rearrangement testing can be performed.

Testing may sometimes be performed to evaluate the effectiveness of lymphoma treatment, that is, to detect residual or recurrent disease, the continued presence of abnormal monoclonal B-cells.

When is it requested?

Testing is performed when a person has signs and symptoms that suggest a lymphoma, such as:

• One or more swollen but painless lymph nodes—depending on the site of the affected lymph node, symptoms may involve areas of the chest, armpit, neck, abdomen, or groin area, for example
• Fatigue
• Fever
• Night sweats
• Unexplained weight loss

Findings from a FBC and differential may be the first indication that a person might have a blood cell cancer as symptoms of early lymphoma may be absent, mild, or nonspecific.

Testing may be done when other laboratory tests indicate that a lymphoma may be present and/or when other tests are inconclusive. Some examples include:

• An increased number of lymphocytes, especially abnormal-looking lymphocytes, as determined with a FBC and a blood film examination
• Signs of lymphoma in a tissue biopsy, body fluid or bone marrow sample
• With immunophenotyping (e.g., flow cytometry, immunohistochemistry), antigen groupings that are inconclusive for a B-cell lymphoma, or when the doctor wants to confirm a diagnosis of lymphoma based on histopathology and immunophenotyping
• In the vast majority of cases, B cell lymphoma can be clearly diagnosed with immunophenotyping or special staining of biopsy specimens, so B cell gene rearrangement studies are only required in rare and difficult to diagnose cases.

Testing may also be ordered when a person has been treated for a lymphoma to evaluate the effectiveness of treatment, that is, to detect residual or recurrent disease.