Immunophenotyping helps doctors diagnose and classify specific blood cell cancers, like leukemia and lymphoma, as well as other diseases.
Immunophenotyping is a lab test doctors use to identify and classify specific cells.
It involves treating a sample of your blood cells with antibodies. Antibodies are proteins that attach to specific types of antigens, or markers, on the surface of white blood cells. Doctors can classify the cells based on these markers.
A doctor may order an immunophenotyping test if they suspect you may have leukemia or lymphoma, or if you have received a diagnosis of one of these cancers.
What is the purpose of immunophenotyping?
Immunophenotyping provides information that helps doctors determine the specific type of cancer and the best treatment for that subtype.
For example, it can distinguish between the types of white blood cells called lymphocytes that your bone marrow creates. Lymphocytes include B cells that remain in your bone marrow and T cells that travel to your thymus , a lymphoid gland in front of your heart.
This information is important for diagnosing cancers such as:
Doctors also use immunophenotyping to determine whether cancer treatment is working and to find other abnormal cells that may indicate disease.
What are the types of immunophenotyping tests?
The primary types of immunophenotyping tests doctors use are:
- flow cytometry
- immunohistochemistry
- immunocytochemistry
Flow cytometry
Flow cytometry is the most common type of immunophenotyping. It identifies certain molecules, called cluster of differentiation (CD) antigens or markers, on the surfaces of your white blood cells by detecting whether specific antibodies adhere to them.
Lab technicians place your blood or bone marrow sample in fluid and treat it with fluorescent antibodies that stain your blood cells.
They then inject the sample into a flow cytometer, a machine that can analyze about 10,000 cells per minute.
The flow cytometer aligns cells from your sample into a single-file line. Each cell then passes through a laser beam that causes the fluorescent dyes to emit light at specific wavelengths.
The amount of light emitted provides information about the cell, such as its size and specific markers. This information is converted to data that a computer can analyze.
The organization Human Cell Differentiation Molecules (HCDM) updates and maintains a list of known CD markers . Some of these markers include:
- T cell markers: CD2, CD4, and CD7
- B cell markers: CD19, CD20, and CD38
- Myeloid cell markers: CD11b, CD15, and CD33
Immunohistochemistry
Immunohistochemistry (IHC) is similar to flow cytometry in that both tests use a sample of blood cells stained with fluorescent antibodies.
However, IHC doesn’t suspend the cell sample in fluid. It analyzes the cells using cell smears or tissue sections embedded in paraffin, a waxy substance.
Instead of a flow cytometer, IHC uses a fluorescent or light microscope to examine the cells for specific antigens.
Immunocytochemistry
Some people use the terms “immunohistochemistry (IHC)” and “immunocytochemistry (ICC)” interchangeably, but they’re not exactly the same.
Both IHC and ICC use a fluorescent microscope to help identify cells, but ICC analyzes antigens in individual cells rather than the entire tissue sample.
While IHC requires a biopsy, doctors can often obtain a sample for ICC using a less invasive method, like a smear or swab.
What is the procedure for immunophenotyping?
To perform immunophenotyping, a healthcare professional first draws blood from a vein in your arm, or a doctor may perform a bone marrow biopsy or aspiration to collect a tissue sample.
If previous tests, such as a complete blood count (CBC) , show abnormal cells in your blood, doctors can perform flow cytometry using a blood sample. It’s less invasive than a biopsy or aspiration.
A tissue sample is necessary for an immunohistochemistry test.
The blood or tissue sample is then sent to a lab for immunophenotyping.
What does an irregular immunophenotype result mean?
An irregular result from immunophenotyping means the CD markers on the surfaces of white blood cells don’t match the usual patterns, indicating the presence of abnormal blood cells.
The result may vary depending on your age. B cell and T cell counts tend to be lower for younger people up to 18 years old. The breakdown of subsets of these cells also changes with age.
If your immunophenotyping result is irregular, a doctor may order further diagnostic tests to determine the reason.
Frequently asked questions
Are flow cytometry and immunophenotyping the same thing?
Flow cytometry is a technique that doctors can use to perform immunophenotyping. Immunophenotyping is a process that helps doctors identify cell types based on specific markers on the cell surface.
What’s the difference between immunophenotyping and immunohistochemistry?
Immunophenotyping is a general term for analyzing and classifying blood cells using antibodies and a fluorescent dye. Immunohistochemistry is a type of immunophenotyping.
What’s the difference between immunohistochemistry and immunocytochemistry?
Immunohistochemistry (IHC) and immunocytochemistry (ICC) both test for specific markers on cells. However, IHC analyzes tissue samples, while ICC analyzes cultured cell samples.
Takeaway
Immunophenotyping helps doctors diagnose and classify some cancers. This lab test uses fluorescent-stained blood or tissue samples to determine whether specific antigens indicating disease are present.
Flow cytometry, an immunophenotyping process, analyzes these samples using a laser beam, while immunohistochemistry uses a fluorescent microscope.
The results of immunophenotyping help a doctor develop an effective treatment plan and outlook for that specific disease.
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