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B-cell Lymphocyte Count (Peripheral Blood)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of B-cells, a type of white blood cell important for producing antibodies that help fight infections and diseases like cancer.

Quick summary

["Understanding your B-cell count can help assess immune function and certain blood disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
40883-1
Short code
CD19CD103BM
Synonyms
CD19+CD103+ Cells NFr Mar
Category
chemistry
Sample
serum
Container
Heparinized bone marrow aspirate in sterile tube (sodium heparin or lithium heparin); EDTA may be acceptable for immunophenotyping panels
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry immunophenotyping
CPT
88184
SNOMED
40910005
Specimen volume
1-3 mL of bone marrow aspirate; minimum 0.5 mL acceptable for pediatric samples
Stability
Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). Do not refrigerate. Viability of cells decreases significantly after 48 hours.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why This Test Is Done

Doctors may order a B-cell count to evaluate immune system health, diagnose conditions like chronic lymphocytic leukemia (CLL), or monitor treatment responses in cancers or autoimmune diseases. It can also help check for infections or other blood disorders.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into a vein, usually in your arm, to draw a blood sample. The process is quick and typically painless.

What the Results Mean

Results show the number of B-cells in your blood. Lower than expected counts may indicate immune deficiencies or certain cancers, while higher counts could suggest overactive immune responses or other conditions. Your doctor will interpret these results in the context of your overall health.

Common Conditions Monitored

This test is often used to monitor conditions like chronic lymphocytic leukemia, autoimmune diseases (e.g., rheumatoid arthritis), or to check immune function before or after treatments like chemotherapy.

Reference range

Reference ranges are laboratory-specific and depend on the percentage of total lymphocytes or bone marrow mononuclear cells analyzed. CD19+CD103+ cells are typically rare in normal bone marrow. Results are interpreted in conjunction with clinical findings and other immunophenotypic markers.N/A

Specimen: serum

No special patient preparation is required. Patient should follow standard pre-procedural instructions for bone marrow aspiration, including informed consent. Recent chemotherapy, immunotherapy, or immunosuppressive therapy may affect results and should be documented.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Abnormal B-cell counts can signal underlying health issues, such as immune system disorders, infections, or cancers. High or low counts may require further testing or adjustments to treatment plans.

Short name

B-Cell Count

Frequently asked questions

What does a low B-cell count mean?
A low B-cell count may suggest an immune deficiency, chronic infections, or certain cancers like chronic lymphocytic leukemia. Your doctor will discuss next steps based on your symptoms and test results.
How often should I get this test?
Frequency depends on your health condition. If you have a chronic illness or are undergoing treatment, your doctor may recommend regular monitoring. Otherwise, it’s usually only done when needed for diagnosis or management.
Can diet or supplements affect B-cell counts?
Dietary changes alone rarely affect B-cell counts, but certain medications (e.g., chemotherapy) or chronic illnesses may influence results. Always follow your doctor’s advice regarding supplements or treatments.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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