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Absolute Count of CD3+ and CD19+ Lymphocytes (Whole Blood)

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

This test measures the total number of two key types of white blood cells—CD3+ T cells and CD19+ B cells—in your blood. These cells play vital roles in your immune system.

Quick summary

["Understanding your immune cell counts can help identify immune system health or disorders."]

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

Key facts at a glance

LOINC
106950-9
Short code
T Lymphocytes.CD3+CD19- NFr Bld FC
Synonyms
T Lymphocytes.CD3+CD19- NFr Bld FC
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

Measuring CD3+ and CD19+ lymphocytes helps doctors assess immune function, especially in conditions like immunodeficiency, infections, or autoimmune diseases. These cells are critical for recognizing and fighting pathogens and coordinating immune responses.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, similar to other routine blood tests. The process usually takes a few minutes.

What the Results Mean

Results show the absolute counts of CD3+ T cells and CD19+ B cells. While specific reference ranges vary by lab, lower-than-expected counts may suggest immune deficiencies, while higher counts could indicate conditions like chronic infections or certain cancers.

Common Conditions This Test Helps Diagnose

This test is often used to diagnose or monitor conditions such as HIV/AIDS, certain leukemias, autoimmune diseases (e.g., lupus), or congenital immune disorders. It can also help evaluate immune responses to treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal lymphocyte counts can signal immune system imbalances, infections, or diseases affecting lymphocyte production or function. For example, low CD3+ or CD19+ counts may indicate weakened immune defense, while elevated counts could suggest overactive immune responses or chronic inflammation.

Short name

Lymphocyte Subset Count

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your medical history, symptoms, and treatment plan. It may be part of routine monitoring for chronic conditions or triggered by specific symptoms like frequent infections.
What does it feel like to have blood drawn?
Most people describe the blood draw as a brief, mild discomfort similar to a pinprick. Afterward, you may feel a slight pinch or bruising at the site, but this usually goes away quickly. Some people report a small bandage or pressure bandage is applied to help with comfort.
Can I eat or drink before this test?
You can eat and drink normally before this test unless your doctor advises otherwise. No special fasting is required.
  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