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Absolute Count of CD19+ B Cells in Peripheral Blood

Published: August 9, 2026Updated: August 15, 2026

This test measures the number of a specific type of white blood cell (B cells) that play a key role in the immune system. It helps assess immune function, especially in conditions affecting B cells.

Quick summary

["This test helps evaluate immune health and diagnose or monitor certain blood disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
40885-6
Short code
CD19CD103
Synonyms
CD19+CD103+ Cells NFr Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) tube, ACD (yellow-top) tube, or sodium heparin (green-top) tube validated for flow cytometry
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 and CD103 surface markers, with subsequent cell population gating and enumeration
CPT
86356
SNOMED
11944002
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric samples
Stability
Process within 24-48 hours of collection when stored at room temperature (20-25°C). Do not refrigerate or freeze whole blood samples as this may affect cell viability and marker expression.
Hemolysis max
50
Lipemia max
100
Icterus max
20
TAT
4–48 hours
Order
routine

Why This Test Is Done

Doctors may order this test if you have symptoms or conditions that suggest an immune system issue, such as frequent infections, autoimmune diseases, or certain cancers (e.g., lymphoma). It may also be used before or after treatments like chemotherapy or immunotherapy that affect B cells.

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 small amount of blood. The process takes a few minutes and is generally comfortable.

How the Test Results Are Used

Results help determine if your immune system has enough healthy B cells to function properly. Abnormal counts may indicate conditions like immune deficiencies, infections, or certain cancers.

Common Conditions Monitored

This test is often used to monitor B cell-related disorders, including chronic infections, autoimmune diseases (like lupus or rheumatoid arthritis), or before/after treatments for blood cancers or immune disorders.

Reference range

Reference ranges vary by laboratory; typically expressed as percentage of total lymphocytes or absolute count (cells/μL). CD19+CD103+ cells are normally present at very low frequencies in peripheral blood of healthy individuals.N/A

Specimen: whole-blood

No special preparation required. Patient should be well-hydrated. Recent blood transfusions, immunosuppressive therapy, or chemotherapy may affect results and should be documented.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Abnormally low or high CD19+ B cell counts can signal underlying immune dysfunction, infection, or malignancy. Doctors will interpret results in the context of your symptoms, medical history, and other tests.

Short name

CD19+ B Cell Count

Frequently asked questions

What does a low CD19+ B cell count mean?
A low count may indicate an immune deficiency, chronic infection, or treatments that suppress B cell production. Your doctor will discuss this with you based on your overall health and test results.
What does a high CD19+ B cell count mean?
A high count could suggest an overactive immune response (e.g., autoimmune disease), a reactive condition, or sometimes a pre-cancerous state. Further evaluation may be needed to understand the cause.
How often should I get this test?
Frequency depends on your medical condition and treatment plan. Your doctor will determine how often this test is needed based on your specific situation.
  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 15, 2026. · Read our editorial policy