B-cell Lymphocyte Count (Absolute)
This test measures the number of B cells, a type of white blood cell involved in producing antibodies to fight infections and help the immune system recognize and remember foreign substances like bacteria and viruses.
["B cells help protect you from infections by identifying and targeting harmful invaders."]
Key facts at a glance
- LOINC
- 107048-1
- Short code
- CD19LAMBM
- Synonyms
- CD19+Lambda+ Cells NFr Mar FC
- Category
- chemistry
- Sample
- serum
- Container
- Sterile heparinized tube (sodium heparin or lithium heparin) for bone marrow aspirate; EDTA tube may be acceptable for some protocols
- Units
- N/A
- Ref low
- 0.4
- Ref high
- 1.5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- flow-cytometry
- CPT
- 86355
- SNOMED
- 39513008
- Specimen volume
- 1-3 mL of bone marrow aspirate in anticoagulant; minimum 0.5 mL for pediatric samples
- Stability
- Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). If delayed, refrigerate at 2-8°C and process within 48 hours. Viability decreases significantly after 48 hours.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Are B Cells?
B cells are a subset of white blood cells that play a critical role in your immune response. They produce antibodies, which are proteins that help your body recognize and neutralize bacteria, viruses, and other foreign substances. This test specifically counts the absolute number of B cells in your bloodstream, which can help doctors assess your immune function or diagnose conditions related to low or high B cell levels.
Why Might You Need This Test?
Your doctor may order a B-cell count test if you have symptoms of an immune disorder, such as frequent infections, unexplained fatigue, or autoimmune conditions. It may also be used to monitor treatment effectiveness in conditions like chronic lymphocytic leukemia (CLL) or other lymphoproliferative disorders.
What to Expect Before the Test
This test typically involves drawing blood from a vein in your arm. You may feel a slight pinch when the needle is inserted, but the procedure usually takes less than five minutes. No special preparation is usually needed, but always follow your doctor’s instructions.
What Happens During the Test?
The blood sample is sent to a lab where it is analyzed to count the number of B cells. The results are usually available within a few days, depending on lab processing times.
Reference range
Reported as percentage of total nucleated cells and absolute count. Normal CD19+ B-cells: 2-22% of lymphocytes; Lambda+ B-cells typically represent approximately 40% of kappa+lambda B-cells (kappa:lambda ratio normally 1.1-2.1). Bone marrow reference values may vary by laboratory.N/A
No special patient preparation required. Patients should be well-hydrated. Recent blood transfusions, immunosuppressive therapy, or chemotherapy may affect results and should be disclosed to the laboratory.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
B-cell counts can help diagnose or monitor conditions such as immune deficiencies, certain cancers (like lymphoma), or autoimmune diseases. Low B-cell counts may indicate immune suppression, while elevated counts could suggest conditions like chronic infections, certain cancers, or immune system overactivity. Always discuss your results with your healthcare provider for personalized interpretation.
Short name
B-Cell Count
Frequently asked questions
What does a low B-cell count mean?
How often should I get this test?
Can lifestyle changes affect B-cell counts?
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