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CD19 Immunoglobulin G (IgG) Detection in Peripheral Blood Cells (Flow Cytometry)

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

This test measures the presence of CD19 immunoglobulin G (IgG) on B cells in your blood, which helps assess immune cell function and identify conditions affecting B-cell development or function.

Quick summary

["This test helps diagnose or monitor immune-related conditions by evaluating B-cell maturity and antibody production."]

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

Key facts at a glance

LOINC
49835-2
Short code
CD19IGD
Synonyms
CD19+IgD+ cells NFr Spec
Category
chemistry
Sample
serum
Container
Heparinized (sodium heparin or lithium heparin) or EDTA anticoagulated whole blood tube; sodium heparin preferred for optimal lymphocyte viability and surface marker preservation
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 and surface immunoglobulin D (IgD) markers, typically with CD45 gating and side scatter analysis
CPT
86356
SNOMED
395124008
Specimen volume
Minimum 3-5 mL whole blood for adults; pediatric microtainer collection of 1-2 mL acceptable for infants and young children
Stability
Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). Optimal results obtained when analyzed within 8 hours of collection. Refrigeration (2-8°C) may be used for delayed processing up to 24 hours but may affect some surface markers.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

CD19 is a protein found on the surface of B cells, a type of white blood cell involved in producing antibodies. This test detects IgG bound to CD19 to evaluate B-cell activity and health. It’s often used alongside other tests to diagnose conditions like chronic lymphocytic leukemia (CLL), autoimmune diseases, or immune deficiencies.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms of an immune disorder, such as frequent infections, unexplained fatigue, or swollen lymph nodes. It may also be used to monitor treatment responses in conditions affecting B cells.

Sample Collection and Preparation

A small blood sample is drawn from a vein in your arm. The blood is processed to isolate B cells, and the test measures IgG bound to CD19 using flow cytometry, a technique that analyzes cell properties under high speed.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications or conditions that might affect blood cells. Avoid strenuous activity the day before if you’re prone to bruising.

Reference range

Reference ranges are laboratory-specific and should be established by each institution. Typical reported values for CD19+IgD+ B lymphocytes as a percentage of total lymphocytes or CD19+ B cells vary by age and clinical context. Pediatric values differ significantly from adult values, with higher proportions of naive (IgD+) B cells in young children that decline with age.N/A

Specimen: serum

No special patient preparation is required. Patients should follow standard phlebotomy guidelines. Recent immunizations, immunosuppressive therapy, or active infection may affect results and should be documented.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CD19 IgG Cells

Frequently asked questions

What does a positive or abnormal result mean?
A positive or abnormal result may signal an immune-related condition, such as an overactive B-cell population (e.g., leukemia) or an immune deficiency. Your provider will interpret results in the context of your symptoms and other tests.
How often will I need this test?
Frequency depends on your diagnosis and treatment plan. Some patients need this test periodically to monitor disease progression or response to therapy, while others may only need it once for diagnosis.
Can I prepare for this test differently if I’m pregnant or have certain conditions?
If you’re pregnant or have conditions like bleeding disorders, discuss any special preparations with your provider before the test. Avoid blood-thinning medications or supplements that may affect blood clotting unless approved.
  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