B-cell Lymphocyte Count (Peripheral Blood)
This test measures the number of B-cells, a type of white blood cell important for making antibodies that help fight infections.
["B-cells help your immune system defend against bacteria and viruses."]
Key facts at a glance
- LOINC
- 57396-4
- Short code
- CD19CD56BF
- Synonyms
- CD19+CD56+ Cells NFr Fld
- Category
- chemistry
- Sample
- serum
- Container
- Sterile collection container (e.g., sterile tube or vacutainer) appropriate for the body fluid type; lavender-top (EDTA) tube commonly used for flow cytometry to prevent clotting and preserve cell viability
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry (immunophenotyping) using fluorescently-labeled monoclonal antibodies against CD19 and CD56 surface markers, typically performed on a body fluid specimen
- CPT
- 88184 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only; first marker) + 88185 (each additional marker) + 88187-88189 (interpretation)
- SNOMED
- 407000003 | Flow cytometry (procedure)
- Specimen volume
- Minimum 3-5 mL of body fluid; larger volumes (up to 10-20 mL) preferred for cell concentration, especially for CSF and other low-cellularity fluids
- Stability
- Specimen should be delivered to the laboratory within 1-2 hours of collection. If immediate processing is not possible, refrigerate at 2-8°C and process within 24 hours. Cell viability decreases significantly after 24 hours.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–48 hours
- Order
- routine
What Are B-Cells?
B-cells are a subset of white blood cells that play a key role in your immune response. They produce antibodies, which are proteins that help identify and neutralize harmful substances like bacteria and viruses. This test helps doctors understand how your immune system is functioning, especially in conditions involving chronic infections, autoimmune diseases, or cancer.
Why Might You Need This Test?
Your doctor may order a B-cell count if you have symptoms like frequent infections, unexplained fatigue, or if you’re being treated for conditions like lymphoma, leukemia, or autoimmune disorders. It can also be part of monitoring for certain immune-related treatments.
What to Expect Before the Test
No special preparation is usually needed. You’ll have a small needle inserted into a vein (often in your arm), and blood will be drawn. This is quick and typically done in a doctor’s office or lab. If you’re nervous, let your healthcare provider know—they can offer comfort measures.
What the Results Mean
Results show the number of B-cells in your blood sample. Lower than expected counts may suggest immune deficiencies or certain cancers, while higher counts could indicate overactive immune responses or other conditions. Your doctor will interpret results in the context of your overall health and symptoms.
Reference range
Reference ranges for CD19+CD56+ cells in body fluid are not well-established and interpretation depends on the specific body fluid type (e.g., cerebrospinal fluid, pleural fluid, peritoneal fluid, synovial fluid). Results should be interpreted in clinical context by a qualified physician. Generally, these cells are rare or absent in most normal body fluids.N/A
No special patient preparation required. However, specimen collection is invasive and must be performed by a qualified healthcare provider using aseptic technique appropriate for the specific body fluid being sampled.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
B-cell count
Frequently asked questions
How is this test different from a general white blood cell count?
Can I eat or drink before this test?
What if my B-cell count is low?
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