B-cell Lymphocyte Count (CD19+ Cells)
This test measures the number of B-cells, a type of white blood cell important for immune function, specifically focusing on those marked by the CD19 protein.
["This test helps assess your immune system’s B-cell activity."]
Key facts at a glance
- LOINC
- 59139-6
- Short code
- CD19CD34BM
- Synonyms
- CD19+CD34+ Cells NFr Mar
- Category
- chemistry
- Sample
- serum
- Container
- Heparinized bone marrow aspirate collected in sterile sodium heparin (green-top) tube or EDTA tube (purple-top) for flow cytometry; sterile collection syringe for aspiration
- Units
- N/A
- Ref low
- 2
- Ref high
- 10
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Flow cytometry (immunophenotyping) using CD19 and CD34 fluorescent-labeled monoclonal antibodies with multiparametric analysis
- CPT
- 88184
- SNOMED
- 44385007
- Specimen volume
- 1-3 mL of bone marrow aspirate (first pull preferred to avoid peripheral blood dilution)
- Stability
- Specimen should be processed within 24 hours of collection when kept at room temperature (20-25°C). Refrigerated storage (2-8°C) may extend stability to 48 hours. Viability decreases significantly beyond these timeframes; delay may compromise CD34+ viability assessment.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Matters
B-cells are crucial for producing antibodies that help fight infections and diseases like cancer. Measuring CD19+ cells helps doctors evaluate immune health, especially in conditions involving abnormal immune responses or cancers that originate from B-cells, such as lymphoma.
How the Test Works
A small sample of your blood is taken and analyzed using flow cytometry, a technique that detects specific cell markers (like CD19) to count the B-cells accurately.
When You Might Need This Test
Your doctor may order this test if you have symptoms of immune disorders, such as frequent infections, unexplained fatigue, or if you’re undergoing treatment for conditions like leukemia, lymphoma, or autoimmune diseases.
Preparation for the Test
No special preparation is needed. You can eat, drink, or take medications as usual on the day of the test. Avoid heavy exercise or stress before the blood draw.
Reference range
Reference ranges vary by laboratory; CD19+ B-lymphocytes and CD34+ hematopoietic progenitor cells in bone marrow are reported as percentage of total nucleated cells or absolute count. CD19+ cells typically 2-10% of marrow nucleated cells; CD34+ cells typically 0.5-2% of marrow nucleated cells. Age-adjusted pediatric and adult reference values differ. Consult laboratory-specific reference intervals for clinical interpretation.N/A
No fasting required. Patient should be informed that bone marrow aspiration involves insertion of a needle into the posterior iliac crest (or sternum in some cases) under local anesthesia. Light sedation may be offered. Patients on anticoagulants should inform the physician; recent chemotherapy, G-CSF administration, or immunotherapy may affect results and should be documented.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low CD19+ cell counts may indicate immune deficiencies, certain cancers (e.g., B-cell lymphoma), or treatments that suppress the immune system. High counts could suggest overactive immune responses or certain infections. This test is often used alongside other blood tests to guide treatment decisions.
Short name
CD19+ Cell Count
Frequently asked questions
What does a low CD19+ cell count mean?
Can lifestyle changes affect CD19+ cell counts?
How often will I need this 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.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy