Immunophenotyping
When a doctor thinks that you may have leukaemia or lymphoma; when you have been diagnosed with leukaemia or lymphoma, but the specific subtype is unknown; sometimes to evaluate the effectiveness of treatment or to evaluate for recurrent disease
A blood sample taken from a vein in your arm; sometimes a bone marrow, tissue, or fluid sample collected by your doctor
A bone marrow aspiration and/or biopsy procedure is performed by a doctor or other trained specialist. 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. Tissue is obtained using a biopsy procedure.
No test preparation is needed.
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How is it used?
Immunophenotyping is requested primarily to help diagnose and classify blood cell cancers (leukaemias and lymphomas). It may be requested as a follow-up test, when a FBC and differential show an increased number of lymphocytes and the presence of immature WBCs or when there is a significant increase or decrease in the number of platelets (thrombocytosis or thrombocytopenia). Testing is most often performed on blood and/or bone marrow samples, but may also be done on body fluids or other biopsy tissue samples.
With immunophenotyping, testing proceeds from the general to the specific. Samples are analysed for panels or groups of specific antigens, and then, based upon the initial findings, additional antigens are analysed as deemed necessary. The number of antigens in a panel will vary from laboratory to laboratory, and the specific panel requested will depend upon the person's clinical findings and the doctor's suspicions.
Testing may sometimes be performed to evaluate the effectiveness of leukaemia or lymphoma treatment and to detect residual or recurrent disease, the continued presence of abnormal cells.
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When is it requested?
Immunophenotyping is requested when a person has an increased number of lymphocytes (or sometimes an increase in another type of WBC), an increased or decreased platelet count, or has immature WBCs that are not normally seen in blood. These are usually findings from a FBC and differential, and they may be the first indication that a person might have a blood cell cancer - as symptoms of early leukaemia and lymphoma may be absent, mild, or nonspecific.
Testing may also be requested when a person has been treated for a leukaemia or lymphoma to evaluate the effectiveness of treatment and detect residual or recurrent disease.
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What does the test result mean?
The patterns of antigens that are produced through immunophenotyping require expertise to interpret. A pathologist often one specialising in the study of blood diseases and/or blood cell cancers (Haematologist), will consider the results from the FBC, differential, blood film, bone marrow findings, and 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 that are present on the cells as detected by immunophenotyping will help characterise the abnormal cells present (if any) as being, for example, B-lymphocytes or T-lymphocytes. This information is considered together with the affected person's clinical history, physical examination, signs and symptoms as well as all laboratory tests to help make a diagnosis.
It must be kept in mind that while findings represent comparisons to "normal" findings and to known associations with leukaemias and lymphomas, each person's condition will also be unique. A person may have (or lack) antigens that are typically seen and still be diagnosed with a specific type of leukaemia or lymphoma.
Abnormal immunophenotype profiles are usually present in: acute myelogenous leukaemia (or acute myeloid leukaemia), acute lymphoblastic leukaemia, B-cell and T-cell non-Hodgkin lymphomas and multiple myeloma.
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Is there anything else I should know?
T-lymphocyte subset analysis based on CD3, CD4 and CD8 expression is performed separately to monitor people with HIV/AIDS. For more on this, see the article on CD4 and CD8.
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Is there a reason to choose one type of sample over another for testing?
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Can immunophenotyping be done in my doctor's surgery?
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Can results of testing be used to determine the course of my cancer?
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Will my antigens change?
The antigens on specific monoclonal cancer cells will generally remain the same, but the overall population of WBCs is constantly being renewed and replaced. Because of this, immunophenotyping results will always be slightly different – they will reflect the current population of WBCs. The test however can confirm, if the disease relapses, if it is the same clone as before or a new clone. Monitoring progress with immunophenotyping may also pick up relapse earlier than other tests.