B-cell count (Absolute Lymphocyte Subset: CD19+ Cells)
This test measures the number of B cells in your blood, specifically those marked by the CD19 protein, which is a key identifier for B lymphocytes—a type of white blood cell involved in immune response.
["Assessing your B-cell count helps evaluate immune function and detect abnormalities in immune system cells."]
Key facts at a glance
- LOINC
- 51336-6
- Short code
- CD19CD43BF
- Synonyms
- CD19+CD43+ Cells NFr Fld
- Category
- chemistry
- Sample
- serum
- Container
- Sterile body fluid collection container (e.g., sterile screw-cap polypropylene tube); anticoagulated with EDTA or heparin for flow cytometry analysis
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 and CD43 surface markers, followed by cell counting via fluorescence-activated cell sorting (FACS) analysis
- CPT
- 86356
- SNOMED
- 407677009
- Specimen volume
- 5-10 mL of body fluid; minimum 1-2 mL acceptable depending on fluid type and cellularity
- Stability
- Specimen should be processed within 4 hours of collection; refrigerate at 2-8°C if processing is delayed beyond 2 hours; do not freeze
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test to diagnose or monitor conditions affecting B cells, such as certain immune deficiencies, autoimmune diseases, or cancers like lymphoma. It may also be used to check immune function before or after treatments that affect white blood cells.
What to Expect Before the Test
No special preparation is needed. You’ll likely have a simple blood draw from a vein in your arm. If you’re on blood-thinning medication, inform your doctor beforehand.
What the Results Mean
Results are typically reported as a count of CD19+ cells per microliter of blood. Lower than expected counts may suggest immune disorders, while higher counts could indicate overactive immune responses or certain blood cancers.
Common Conditions Monitored
This test is often used to monitor conditions like chronic lymphocytic leukemia (CLL), where B cells proliferate abnormally, or to assess immune recovery after treatments like chemotherapy or radiation.
Reference range
CD19+CD43+ cells are normally rare in body fluids. Reference ranges vary by fluid type; typically reported as percentage of total lymphocytes or as absolute count per microliter. Consult laboratory-specific reference ranges for the specific body fluid analyzed.N/A
No special patient preparation required. Inform the ordering physician of any recent immunotherapy, chemotherapy, or immunosuppressive medications that may affect lymphocyte populations.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD19+ Cell Count
Frequently asked questions
What does a CD19+ cell count measure?
Does this test require fasting?
Can I take my usual medications before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy