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B-cell CD19 and CD38 Immunophenotyping (Flow Cytometry) – Peripheral Blood

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

This test measures the presence and proportion of B-cells expressing CD19 and CD38 markers in your blood, often used to assess immune cell populations or evaluate conditions affecting B-cells.

Quick summary

["This test helps doctors understand how your immune system’s B-cells are functioning, which can guide treatment for blood disorders or immune-related conditions."]

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

Key facts at a glance

LOINC
59147-9
Short code
CD19CD38
Synonyms
CD19+CD38+ Cells # Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) vacutainer tube; alternatively, sodium heparin (green-top) tube is acceptable for flow cytometry applications. ACD (yellow-top) tubes may also be used. Tubes must be filled to stated volume to maintain proper anticoagulant ratio.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 and CD38 surface markers, typically performed on whole blood with erythrocyte lysis prior to acquisition on a clinical flow cytometer. CD19 identifies pan-B lymphocytes; CD38 expression characterizes activated B cells, plasmablasts, and plasma cell precursors.
CPT
86356 (Mononuclear cell antigen, quantitative, not otherwise specified); additional 86359 (T cells, total count) and 86360 (T cells, absolute CD4 and CD8 count) may apply depending on full panel ordered
SNOMED
399009007 (B lymphocyte count); 40640006 (CD19 antigen); 119376003 (CD38 antigen)
Specimen volume
3-5 mL of whole blood in EDTA; minimum 1 mL for pediatric or limited samples. Peripheral blood draw via standard venipuncture.
Stability
Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Refrigeration (2-8°C) may extend viability up to 72 hours, but prolonged storage may alter surface marker expression and cell viability. Do not freeze whole blood specimens.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–72 hours
Order
routine

Why This Test Is Done

Doctors may order this test to diagnose or monitor conditions such as leukemia, lymphoma, or other blood disorders. It can also help track immune responses during treatments like chemotherapy or immunotherapy. Sometimes, it’s used to check for abnormal B-cell activity in people with autoimmune diseases or infections.

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 about 5 minutes, and you may feel a brief pinch. If you’re nervous, let your doctor or nurse know.

What Happens During the Test

The blood sample is analyzed using flow cytometry, a technique that separates and identifies different cell types based on their surface markers, including CD19 and CD38. This helps determine the number and proportion of B-cells in your blood.

What the Results Mean

Results show the percentage of B-cells expressing these markers. Abnormal levels may indicate conditions like B-cell leukemia, lymphoma, or other immune system issues. Your doctor will interpret the results in the context of your medical history and symptoms.

Reference range

Reference ranges are laboratory-specific and vary by age and clinical context. In healthy adults, CD19+CD38+ B cells typically represent a subset of total CD19+ B lymphocytes. Absolute counts vary by instrumentation and antibody clones used; consult your laboratory's reference interval.N/A

Specimen: whole-blood

No fasting required. Patients should be adequately hydrated. Avoid recent live vaccinations or immunosuppressive therapy prior to draw when clinically feasible, as these may transiently alter lymphocyte subset populations. Inform the laboratory of any current immunosuppressive or immunomodulatory medications (e.g., rituximab, corticosteroids).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

B-cell marker analysis

Frequently asked questions

What does a high or low level of CD19/CD38+ B-cells mean?
High levels of CD19+ and CD38+ B-cells may suggest conditions like chronic lymphocytic leukemia (CLL), non-Hodgkin lymphoma, or other B-cell malignancies. Low or absent levels could indicate immune deficiencies or treatments that suppress B-cell activity.
How often will I need this test?
Your doctor will determine how often you need this test based on your diagnosis, treatment plan, and symptoms. Some patients need it monthly, while others may only need it once or twice a year.
Can I eat or drink before this test?
You can eat and drink normally before the test, as no fasting is required. However, inform your doctor if you’re taking any medications, as they may affect blood results.
  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