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To help diagnose and classify a leukemia or lymphoma; to help guide treatment; to aid in determining prognosis; to detect and evaluate leukemia or lymphoma cells that remain after treatment or at disease relapse
When you have signs and symptoms that a healthcare practitioner thinks may be due to leukemia or lymphoma; to help classify the type of leukemia or lymphoma, identify treatment options, and predict the likely course of the disease; to evaluate whether treatment has been effective or detect disease that remains or comes back after treatment (relapse or recurrence)
A blood sample is obtained by inserting a needle into a vein. A bone marrow sample may be collected from the hip bone by a trained healthcare practitioner. (For more details, read the article on Bone Marrow Aspiration and Biopsy.) Sometimes, a tissue sample, such as from a lymph node, is obtained using a biopsy or fine needle aspiration (FNA) procedure. Body fluid samples are obtained through collection of the fluid in a container or by inserting a needle into the body cavity and aspirating a portion of the fluid with a syringe.
Immunophenotyping by flow cytometry is a laboratory method that detects the presence or absence of white blood cell (WBC) markers called antigens. These antigens are protein structures found on or within WBCs. Specific groupings of these antigens are normally present on or within WBCs and are unique to specific cell types and stages of cell maturation. Additionally, specific patterns of antigens are present on abnormal cells seen in leukemias and lymphomas. Flow cytometry immunophenotyping may be useful in helping to diagnose, classify, treat and determine prognosis of these blood cell cancers.
Leukemias and lymphomas are caused by an abnormal white blood cell that begins to divide uncontrollably, making numerous copies of itself (clones). The abnormal cells grow, but they do not fight infections or perform other functions like normal WBCs. They do not die at a normal rate, so they accumulate in the bone marrow, lymph nodes, or other tissues. As the number of abnormal cells increases in the bone marrow, they may crowd out and inhibit the production of normal white blood cells, red blood cells, and platelets, and eventually abnormal cells may also be released into the blood. As the number of abnormal cells increase in a lymph node, the size of the lymph node increases. Sometimes lymphomas also involve the blood and/or bone marrow.
If you have a leukemia or lymphoma, routine tests such as a complete blood count (CBC) and a WBC differential may show an increased number of white blood cells with a predominance of one type. These tests may suggest lymphoma or leukemia, but more information is generally needed to confirm a diagnosis and to identify a specific type of leukemia or lymphoma.
Flow cytometry immunophenotyping may be performed on blood, bone marrow, or other samples to provide this additional information. It can detect normal cells as well as abnormal cells whose pattern of markers are typically seen with specific types of leukemia and lymphoma. The results may also be used to predict how aggressive the cancer will be and/or whether it will respond to certain treatment. (For details on this laboratory method, read the article on Flow Cytometry.)
Most of the antigens that flow cytometry immunophenotyping detects are identified by a CD (clusters of differentiation or cluster designation) number (see the table in the "What does the test result mean?" section under Common Questions). CD numbers represent a naming convention that is based on international consensus. While hundreds of antigens have been identified and have a unique CD number, only a small number of these are routinely used.
Flow cytometry immunophenotyping is used primarily to help diagnose and classify blood cell cancers (leukemias and lymphomas) and to help guide their treatment. It may be used in follow up to a complete blood count (CBC) and WBC differential that show an increased number of lymphocytes or the presence of immature blood cells or other abnormal cell counts.
Flow cytometry immunophenotyping may also be used:
There are some other uses of this testing that are less common, but they are not addressed in this article.
Flow cytometry immunophenotyping may be ordered when you have an increased number of lymphocytes (or sometimes an increase in another type of white blood cell, WBC), anemia, a decreased platelet count, or immature WBCs that are not normally seen in the blood. These may be the first indication of a possible blood cell cancer.
Testing may be done when you have signs and symptoms of leukemia and lymphoma, though they may be unremarkable, mild, or nonspecific early in the disease.
Examples of signs and symptoms of a blood cell cancer include:
Testing may also be ordered after you have been treated for leukemia or lymphoma.
A pathologist, often one specializing in the study of blood diseases and/or blood cell cancers (a hematopathologist), will consider the results from the complete blood count (CBC), differential, blood smear, bone marrow findings, and flow cytometry immunophenotyping as well as other tests in order to provide a diagnostic interpretation. A laboratory report will typically include specific results from the tests as well as an analysis of what those results mean.
The markers (antigens) that are present on the cells as detected by flow cytometry immunophenotyping will help characterize the cells present. A normal cell will display a pattern of antigens that correlates with the type and maturity of the cell. (Blood cells normally mature in the bone marrow and are released into circulation when they are mature or nearly mature.) The results from your immunophenotyping are compared to the pattern of antigens for “normal” cells as well as to patterns that are associated with abnormal cells (e.g., cells present with leukemias and lymphomas).
Your healthcare practitioner will consider the flow cytometry immunophenotyping results together with your clinical history, physical examination, signs and symptoms, as well as all laboratory tests to help make a diagnosis.
Each person's condition will be unique. You may have (or lack) certain antigens that are typically seen, yet you may still be diagnosed with a specific type of leukemia or lymphoma.
Here is one example:
Abnormal immunophenotype profiles are usually present in:
The following summarizes markers that are often expressed in certain types of cells:
|Immature precursor cells||CD34, CD117, TdT|
|B-lymphocytes||CD19, CD20, CD22, CD79a, immunoglobulin light chains (kappa or lambda)|
|T-lymphocytes||CD2, CD3, CD5, CD7, and either CD4 or CD8|
|Myeloid cells (granulocytes)||MPO (myeloperoxidase), CD13, CD33|
|Natural killer (NK) cells||CD16, CD56|
The following summarizes markers that suggest certain types of cell differentiation:
|Megakaryocytic differentiation; Platelets||CD41, CD42b, CD61|
|Red blood cell (erythroid) differentiation||CD235a|
|Monocytic differentiation||CD11b, CD14, CD33, HLA-DR|
|Hairy cell leukemia||CD11c, CD25, CD103|
T-lymphocyte subset analysis based on CD3, CD4 and CD8 expression is performed separately to monitor people with HIV/AIDS, for example. For more on this, see the article on CD4 Count.
The type of sample to be tested is up to your healthcare practitioner and must be representative of your cancer. If abnormal cells are present in the bloodstream, a blood sample is often used for flow cytometry immunophenotyping as it is easy to obtain and less invasive than other collection methods. However, lymphoma cells may or may not find their way to the bloodstream and might require other collection techniques.
It depends. It is not offered in every laboratory, but many larger hospitals and academic medical centers perform the testing or your sample may be sent to a reference laboratory.
Diagnosis of leukemia or lymphoma is based on the visual examination of a blood smear and/or bone marrow biopsy and aspiration for the presence of certain cell types. Depending upon flow cytometry immunophenotyping results, a healthcare practitioner may determine how likely your cancer will respond to treatment and how aggressive the treatment might be. The course of treatment for your cancer will be determined by your healthcare practitioner and their team based on flow cytometry immunophenotyping and other tests that might be performed.
It depends. The antigens on specific leukemia or lymphoma cells may remain the same over time. However, treatment with chemotherapy may eliminate the abnormal cells, and if treatment is successful, normal white blood cells (WBCs) will replace abnormal cells. Because of this, immunophenotyping results will be different by reflecting the current population of WBCs that would be present in an individual in remission. Sometimes, however, the cancer cells adapt to evade the therapy by not expressing anymore an antigen that they expressed earlier, which might have been targeted by a monoclonal antibody or other therapy, like CAR T-cells.
Originally, glass slides with fixed tissue sections were treated with an antibody that was specific for a type of antigen typically found on certain abnormal cells associated with a particular leukemia or lymphoma. These antibodies were often linked with a fluorescent or a chemical indicator that would make these abnormal cells visible when observed under a microscope. This approach, called immunohistochemistry, is used every day for some leukemia and lymphoma markers and other types of cancer. It may be because the markers of interest are not available for flow cytometry or because fresh cells or tissue are not available (a requirement for flow cytometry immunophenotyping).
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