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B-cell Immunophenotyping by Flow Cytometry (CD19+ CD27+ Cells in Whole Blood)

Published: August 9, 2026Updated: August 15, 2026

This test measures the presence of specific immune cells (B-cells) in your blood using a technique called flow cytometry. It helps assess certain immune conditions, including chronic lymphocytic leukemia (CLL) or other B-cell disorders.

Quick summary

["This test helps doctors track immune cell activity and diagnose or monitor certain blood-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
89353-7
Short code
CD19CD27
Synonyms
CD19+CD27+ cells # Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender-top) or heparin (green-top) anticoagulated blood collection tube; ACD-A also acceptable
Units
N/A
Ref low
20
Ref high
120
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Flow cytometry (fluorescence-activated cell sorting, FACS) using monoclonal antibodies against CD19 and CD27 surface markers; reported as absolute count per microliter of blood
CPT
86355
SNOMED
259300009
Specimen volume
1–3 mL of whole blood; minimum 0.5 mL for pediatric or low-volume samples
Stability
Specimen should be processed within 24–48 hours of collection when stored at room temperature (18–25°C); do not refrigerate or freeze as this may affect cell viability and marker expression
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
4–48 hours
Order
routine

What This Test Measures

Flow cytometry analyzes blood samples by detecting markers (CD19 and CD27) on the surface of immune cells. CD19 is a protein found on most B-cells, while CD27 is a marker that can help distinguish between different types of mature B-cells. The test counts and identifies cells expressing these markers to provide a profile of your B-cell population.

Why It’s Done

Doctors may order this test if you have symptoms of an immune disorder, such as frequent infections, unexplained fatigue, or swollen lymph nodes. It’s also used in the diagnosis, monitoring, or evaluation of conditions like chronic lymphocytic leukemia (CLL), autoimmune diseases, or immune deficiencies.

Sample Collection and Preparation

A small amount of blood is drawn from a vein, typically in your arm. The blood sample is then processed in the lab to separate and analyze the immune cells using flow cytometry, which detects the CD19 and CD27 markers on the cell surface.

Test Results Interpretation

Results are expressed as a percentage or count of CD19+ CD27+ cells in your blood sample. While specific reference ranges aren’t provided here, doctors compare your results to what’s typical for healthy individuals or to your baseline levels over time to determine if further action is needed.

Reference range

Reference ranges vary by laboratory and instrumentation; typical adult values for CD19+CD27+ B cells range from 20–120 cells/μL (approximately 1–7% of total lymphocytes); consult laboratory-specific reference intervalN/A

Specimen: whole-blood

No fasting required; recent vaccination, immunosuppressive therapy, or B-cell depleting treatments (e.g., rituximab) may affect results and should be noted

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal levels of CD19+ CD27+ B-cells can indicate conditions such as CLL, where B-cells proliferate uncontrollably. They may also be relevant in monitoring immune responses in autoimmune diseases or infections. Doctors use these results to guide treatment decisions, such as starting medication or adjusting therapy based on your immune cell profile.

Short name

B-cell marker profile

Frequently asked questions

What does a CD19+ CD27+ B-cell count mean?
A CD19+ CD27+ B-cell count alone isn’t a standalone diagnosis. Your doctor will consider your symptoms, medical history, and other test results to interpret the meaning of these findings. For example, elevated counts might suggest a B-cell disorder, while normal levels may not rule out other conditions.
How often will I need this test?
The frequency of this test depends on your medical condition and treatment plan. If you’re being monitored for a chronic condition like CLL, your doctor may order follow-up tests at regular intervals (e.g., every few months). Always follow your healthcare provider’s instructions.
Can I prepare for this test?
No special preparation is needed for this blood test. However, avoid taking certain medications (like blood thinners) without consulting your doctor, as they may affect blood analysis. If you have questions about your medications, ask your healthcare provider before the test.
  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 15, 2026. · Read our editorial policy