Flow Cytometry vs PARR

Flow cytometry and PARR are newer diagnostics used in cases of lymphoma and leukemia. We use these tests more so in dogs, as they are not as reliable in cats.

Flow cytometry is a type of immunophenotyping that detects the expression of cell surface and intracellular antigens, along with their level of expression. Cells are exposed to antibodies against different proteins. These antibodies are bound to a different set of fluorescent antibodies. Once bound, these latter antibodies emit a degree of light that is proportional to the amount of antibody bound. This diagnostic cannot be performed on serum or slides. The sample has to be fresh and ideally taken within 48 hours of testing. This test can be done on blood, cavity effusions, and lymph node tissue.

PARR stands for PCR for Antigen Receptor Rearrangement and is a clonality assay. Every naive B and T cell has its own unique receptor. PARR can detect a monoclonal expansion of neoplastic lymphocytes. This distinguishes it from an inflammatory population which is polyclonal. This test can be performed on blood, bone marrow, lymph node tissue, and cavity effusions. It differs from flow cytometry in that it can be performed on cytology slides.

Which test you submit depends on clinical signs and what specific diagnostic information you are seeking. If you need to confirm neoplasia, then PARR is preferred because it can not only determine if a neoplastic population is present but also provide phenotype. The other instance PARR is preferred is when you have dead tissue (ie. lymph node cytology slides). Flow cytometry is especially helpful in distinguishing among the various types of leukemia in patients with a lymphocytosis.

These two diagnostics have allowed us to learn more details about lymphoma and leukemia cases. This data can guide our treatment recommendations and provide prognostic information.

Learn more about the Oncology service at NorthStar VETS

Dorothy Jackson, DVM, DACVIM (Oncology)Dorothy Jackson, DVM, DACVIM (Oncology)
Originally from the South, Dr. Jackson attended Mississippi State University for her undergraduate studies and veterinary school. Following veterinary school in 2009, she completed a rotating internship at the University of Missouri followed by a specialty internship at Georgia Veterinary Specialists in Atlanta. Dr. Jackson was lucky enough to obtain both academic and private practice experience during her residency, training at the University of Pennsylvania and Veterinary Cancer Center in Connecticut. Following her residency, Dr. Jackson obtained board certification in Oncology and worked at Red Bank Veterinary Hospital for 2.5 years before joining the Northstar VETS team.

Being an Italian from the South, Dr. Jackson loves food. She loves cooking new recipes and trying new restaurants with her girlfriend…another Italian. When not traveling to new places, they enjoy their time at home with their 3 cats who keep them quite entertained.

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