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B-cell Lymphocyte Count (Absolute Count) from Whole 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.

Quick summary

["B cells help your immune system defend against pathogens like bacteria and viruses."]

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

Key facts at a glance

LOINC
38511-2
Short code
CD19CD33
Synonyms
CD19+CD33+ Cells NFr Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA) or ACD-A anticoagulant tube for flow cytometry; sodium heparin tube may be acceptable per laboratory protocol
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry using fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugated antibodies targeting CD19 (B-lymphocyte marker) and CD33 (myeloid lineage marker) surface antigens. Specimen analysis performed on whole blood with erythrocyte lysis followed by multi-color flow cytometric enumeration of dual-positive cell populations.
CPT
86355
SNOMED
270981003
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric samples
Stability
Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C); do not refrigerate as this may affect cell viability and marker expression
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order this test to evaluate your immune system, check for infections, monitor conditions like lupus, rheumatoid arthritis, or chronic infections, or assess responses to treatments for blood disorders or autoimmune diseases.

What to Expect Before the Test

No special preparation is typically needed. You may be asked to fast for 8–12 hours before the test if blood is drawn from a vein, but if drawn from a fingerstick, fasting is usually not required.

How the Test Is Performed

A healthcare professional will insert a needle into a vein in your arm or hand to draw a small amount of blood. The blood sample is then analyzed to count the absolute number of B cells.

What the Results Mean

Results are reported as the absolute count of B cells per microliter (µL) of blood. Lower than expected counts may suggest immune deficiencies or certain cancers, while higher counts could indicate overactive immune responses or other conditions.

Reference range

Reference values for dual CD19+CD33+ positive cells in peripheral blood are generally very low or undetectable in healthy individuals. Co-expression of CD19 (pan-B cell) and CD33 (myeloid) is considered aberrant in normal hematopoiesis. Reported as percentage of total nucleated cells or absolute count; reference values must be established by individual performing laboratory.N/A

Specimen: whole-blood

No special patient preparation required. Specimen should be collected prior to chemotherapy, immunosuppressive therapy, or blood transfusion when possible, as these treatments may affect lymphocyte subset enumeration.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal B-cell counts can indicate underlying health issues, such as immune system disorders (e.g., hypogammaglobulinemia), infections, or malignancies like lymphoma or leukemia. Monitoring these cells helps guide treatment decisions for chronic conditions or immune-related diseases.

Short name

B-cell count

Frequently asked questions

What causes B-cell counts to be low?
Low B-cell counts can result from immune system disorders, certain medications, chronic infections, or genetic conditions. It may also be seen in people with autoimmune diseases or those undergoing chemotherapy.
What causes B-cell counts to be high?
High B-cell counts may occur in chronic infections, certain autoimmune diseases, or reactive conditions. In some cases, it could be part of a blood disorder like monoclonal gammopathy or lymphoma.
How often should this test be repeated?
Frequency depends on your medical condition and treatment plan. Your healthcare provider will determine how often to repeat this test based on your individual needs and symptoms.
  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