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CD38 Immunoglobulin G (IgG) on B Cells (Cell Count)

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

This test measures the number of B cells expressing CD38, a protein often associated with immunoglobulin production, specifically focusing on those producing IgG antibodies. It may be used to evaluate immune function or identify abnormalities in B cell populations.

Quick summary

["Assessing B cell health and antibody production in immune-related conditions."]

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

Key facts at a glance

LOINC
89341-2
Short code
CD38IgMCD19
Synonyms
CD38+IgM+ cells/Cells.CD19 NFr Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (purple-top) or ACD (yellow-top) anticoagulated blood collection tube; sodium heparin (green-top) may also be acceptable for flow cytometry applications
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
Flow cytometry using fluorescently-labeled monoclonal antibodies (anti-CD38, anti-IgM, anti-CD19) to enumerate and phenotype B-lymphocyte subpopulations in peripheral blood
CPT
86356 (if combined panel) or 88184/88185 (flow cytometry component); specific CPT code depends on panel composition and billing bundling
SNOMED
258566006 (or LOINC-mapped equivalent for B-lymphocyte subset analysis)
Specimen volume
3-5 mL of whole blood for adults; minimum 1 mL for pediatric patients
Stability
Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Do not refrigerate, as cold temperatures may cause loss of cell surface markers. If processing delay is anticipated, use a stabilizing transport medium per laboratory protocol.
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 recommend this test if you have symptoms or conditions linked to abnormal B cell activity, such as chronic infections, autoimmune diseases, or certain cancers like lymphoma. It could also be part of monitoring for immune disorders or evaluating responses to treatments.

What to Expect Before the Test

No special preparation is typically needed. Blood will be drawn from a vein in your arm, similar to other blood tests. You may feel slight discomfort, but it usually lasts only a few minutes. If you’re on blood thinners or have a history of bleeding issues, let your provider know.

What the Results Mean

Results compare the count of CD38+ IgG-producing B cells to a baseline or reference range for healthy individuals. Abnormal counts may suggest immune dysfunction, overactive or underactive immune responses, or conditions affecting B cell maturation.

Common Conditions Monitored

This test may help diagnose or track conditions like chronic lymphocytic leukemia (CLL), Waldenström macroglobulinemia, or other B cell-related disorders. It can also be used in research or specialized clinical settings to study immune cell behavior.

Reference range

Reference ranges vary by laboratory and age. Typically reported as percentage of CD19+ B cells or absolute count (cells/μL). Consult the performing laboratory's reference interval for specific values.N/A

Specimen: whole-blood

No special patient preparation required. Fasting is not necessary. Patient should be well-hydrated. Recent corticosteroid therapy, chemotherapy, immunosuppressive drugs, or rituximab (anti-CD20) therapy may significantly alter B-cell subset distributions and should be documented at time of collection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG CD38+ B Cell Count

Frequently asked questions

What does a CD38+ IgG B cell count measure?
It quantifies B cells expressing CD38, a marker often linked to immunoglobulin production, specifically IgG antibodies. This helps assess B cell health and function in immune-related conditions.
How is this test different from a general B cell count?
This test specifically targets B cells producing IgG and checks for CD38 expression, which is not measured in a standard B cell differential. It provides more targeted insight into a subset of B cells involved in antibody production.
Can this test be done at home?
No, this test requires a blood sample drawn in a clinical setting by a healthcare professional. Results are typically reported within a few days to a week, depending on lab processing times.
  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