Skip to content

Comprehensive B-cell Subtype Analysis (CD21 and CD19 Flow Cytometry)

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

This test measures specific markers (CD21 and CD19) on B-cells in your blood to help identify and characterize different types of B-cells, often used in diagnosing and monitoring conditions like lymphoma or immune disorders.

Quick summary

["This test helps doctors understand your immune system’s B-cell activity and potential abnormalities."]

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

Key facts at a glance

LOINC
94754-9
Short code
CD21L38N
Synonyms
CD21low38- Cells/Cells.CD19 NFr Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA) or sodium heparin tube; ACD tube also acceptable for flow cytometry
Units
N/A
Ref low
2
Ref high
10
Fasting
false
Population
adult
Sex
all
Age range
0–99 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies (CD19, CD21, CD38) with multiparameter immunophenotyping
CPT
88184
SNOMED
395145001
Specimen volume
3-5 mL whole blood (minimum 1 mL for pediatric samples)
Stability
Specimen should be processed within 24-48 hours of collection at room temperature (18-25°C). Do not refrigerate if processing will be delayed more than 24 hours; keep at room temperature
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–48 hours
Order
routine

Why This Test Is Done

Doctors may order this test if you have symptoms like persistent fatigue, unexplained weight loss, swollen lymph nodes, or if they suspect conditions like chronic lymphocytic leukemia (CLL), non-Hodgkin lymphoma, or other immune-related diseases. It can also be part of monitoring treatment progress.

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), and a small amount of blood will be drawn. The process takes about 5 minutes, and you may feel a brief pinch. The blood sample is then analyzed in a lab to detect specific cell markers.

What the Results Mean

The test identifies the presence and proportion of B-cells expressing CD21 and CD19 markers. Abnormal levels or patterns may indicate conditions affecting B-cell function or proliferation, such as certain cancers or immune deficiencies. Your doctor will interpret the results in the context of your symptoms and medical history.

Common Conditions This Test Helps Diagnose

This test is often used to diagnose or monitor conditions like chronic lymphocytic leukemia (CLL), non-Hodgkin lymphoma, Waldenström macroglobulinemia, and other B-cell-related disorders. It may also help assess immune system health in patients with autoimmune diseases or after stem cell transplants.

Reference range

CD21lowCD38- B cells as a percentage of total CD19+ B cells in peripheral blood; reference values vary by laboratory. Typical adult reference range: 2-10% of CD19+ B cellsN/A

Specimen: whole-blood

No special preparation required. Avoid recent immunosuppressant therapy if clinically feasible, as it may affect lymphocyte subset distribution

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: How Results Impact Treatment

Short name

B-cell Immunophenotyping

Frequently asked questions

What does a low count of CD21+ B-cells mean?
A low count of CD21+ B-cells may suggest an immune deficiency or certain types of B-cell malignancies. Your doctor will discuss this with you in detail, considering other test results and your overall health. Conditions like CLL or autoimmune disorders may also be explored.
Can this test detect early signs of lymphoma?
Yes, this test can help detect early signs of lymphoma by identifying abnormal B-cell populations. While it’s not the only test used, it provides critical information about B-cell health that guides further evaluation and treatment planning.
How often should I get this test if I have a known condition?
Your doctor will determine how often you need this test based on your specific condition, treatment plan, and response to therapy. Regular monitoring may be scheduled to track changes in your B-cell counts and overall health.
  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