April 3, 2023

CD19 is a protein primarily expressed on the surface of B cells, a type of white blood cell that plays a key role in the immune system’s defense against infections. This protein is expressed throughout the entire B cell development process, from pre-B cells to mature B cells where it is involved in the regulation of B cell activation, differentiation, and proliferation. This protein is also expressed by some plasma cells, which are B cells that produce antibodies. Other B cell markers include CD20, CD79, and PAX-5.

Two common tests used to look for CD19 in a tissue sample are immunohistochemistry and flow cytometry. Immunohistochemistry is performed on a tissue sample attached to a glass slide. The slide is then examined under the microscope. Flow cytometry uses a special machine to count and analyze the number of cells in a tissue sample that are making this protein.

Can normal cells be positive for CD19?

Yes. Normal, healthy B cells are positive for CD19. These cells are found throughout the body.

CD19 positive cancers

Most lymphomas that start from B cells will be positive for CD19.

CD19-positive lymphomas include:

About this article

Doctors wrote this article to assist you in reading and comprehending your pathology report. Feel free to reach out to us with any questions about this article or your pathology report. To get a comprehensive introduction to your pathology report, read this article.

Other helpful resources

Atlas of pathology
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