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B-cell CD19 Immunoglobulin G (IgG) Quantification in Peripheral Blood Cells

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody produced by B-cells (a type of white blood cell), in your blood. It helps assess immune function and identify conditions affecting B-cell activity.

Quick summary

["This test helps evaluate your immune system’s ability to produce antibodies and diagnose or monitor certain immune disorders."]

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

Key facts at a glance

LOINC
49840-2
Short code
CD19IGG
Synonyms
CD19+IgG+ cells NFr Spec
Category
chemistry
Sample
serum
Container
Heparinized (sodium heparin or lithium heparin) tube preferred; EDTA tube acceptable; ACD tube acceptable for immunophenotyping. Sterile collection required.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Flow cytometry using fluorescently labeled antibodies against CD19 and surface immunoglobulin G (IgG). Cells are analyzed on a flow cytometer with appropriate gating strategies to identify CD19+ B lymphocytes expressing surface IgG.
CPT
86356 (for flow cytometry, cell surface, total lymphocyte count); may also include 88184/88185 (flow cytometry interpretation)
SNOMED
39754003 | 14990007
Specimen volume
2–5 mL of peripheral blood; minimum 1 mL for pediatric samples
Stability
Specimen should be processed within 24 hours of collection when stored at room temperature (18–25°C). May be stored up to 48 hours at 4°C if processing is delayed, but viability may decrease. Do not freeze whole blood.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms like frequent infections, low antibody levels, or if you’re being evaluated for conditions such as immunodeficiency, chronic lymphocytic leukemia, or autoimmune diseases. It may also be used to monitor treatment responses in patients with B-cell-related disorders.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm or vein to draw a blood sample. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

Results are compared to general reference ranges for healthy adults, but individual results can vary based on age, health status, and other factors. Abnormal levels may indicate immune system issues or other underlying health concerns.

Common Conditions Affecting Results

Low IgG levels may suggest primary immunodeficiency, chronic infections, or malabsorption issues. High levels could be seen in certain autoimmune diseases or overactive immune responses, though this is less common for IgG alone.

Reference range

Reference values vary by laboratory; typically expressed as percentage of CD19+ B cells or absolute count (cells/µL). Adult reference range approximately 0.5–2.5% of total lymphocytes or 1–5 cells/µL for CD19+IgG+ B cells. Pediatric values differ.N/A

Specimen: serum

No special preparation required. Patients on immunosuppressive therapy (e.g., rituximab, corticosteroids) may have altered results and should be reported to the laboratory. Recent vaccinations may transiently affect B-cell subsets.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CD19+ B-Cell IgG Level

Frequently asked questions

What does a low IgG level in B-cells mean?
A low IgG level in B-cells may indicate an impaired immune response, potentially due to primary immunodeficiency, chronic infections, or conditions affecting antibody production. Your provider will discuss further testing or treatment options based on your overall health and symptoms.
Can diet affect this test result?
Dietary factors may indirectly influence immune function, but they typically do not directly affect IgG levels in B-cells. Avoiding extreme dietary changes before testing is recommended to reduce variability in results.
Is this test painful?
The blood draw itself is usually mild discomfort for a few seconds. Most people feel minimal pain or only a slight pinch. If you’re anxious, let your provider know to discuss options like numbing cream or alternative testing methods.
  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