CD3+ T Cell Count (Absolute)
This test measures the number of CD3-positive cells in your blood, which are a key type of white blood cell involved in immune function.
["CD3 cells help your immune system fight infections and recognize foreign substances."]
Key facts at a glance
- LOINC
- 106963-2
- Short code
- CD3CD5
- Synonyms
- CD3+CD5+ cells NFr Spec FC
- Category
- chemistry
- Sample
- serum
- Container
- Heparinized (sodium heparin or lithium heparin) green-top tube or ACD (acid citrate dextrose) tube for flow cytometry. EDTA tubes may be acceptable but heparin is preferred for optimal cell viability and antigen preservation.
- Units
- N/A
- Ref low
- 58
- Ref high
- 84
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- flow-cytometry
- CPT
- 86355
- SNOMED
- 396891006
- Specimen volume
- 3-5 mL of whole blood for adults; minimum 1-2 mL for pediatric patients. Bone marrow or tissue specimens may also be acceptable depending on clinical indication.
- 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 may affect certain surface markers. Do not freeze. Ship at room temperature if referring to an outside laboratory.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What Are CD3 Cells?
CD3 cells are a marker found on the surface of T lymphocytes (a type of white blood cell). They play a critical role in activating T cells to respond to infections, cancer, and other immune challenges. This test helps assess your immune system’s ability to recognize and attack harmful invaders.
Why Might You Need This Test?
Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or if you’re undergoing treatment that could affect your immune response (e.g., chemotherapy, certain medications). It may also be used to monitor immune function in conditions like HIV/AIDS or autoimmune diseases.
How Is the Test Performed?
A small sample of blood is drawn from a vein, usually in your arm. The blood is then analyzed in a lab to count the number of CD3+ cells present. This is typically done using flow cytometry, a precise method that identifies and measures different types of immune cells.
What Do the Results Mean?
Results are usually reported as a count of CD3+ cells per microliter (µL) of blood. While specific reference ranges can vary by lab, lower than expected counts may suggest immune suppression, while higher counts might indicate overactive immune responses or other conditions.
Reference range
CD3+CD5+ cells typically represent 58-84% of total lymphocytes in healthy adults. Absolute counts generally range from 850-2,400 cells/µL. Reference ranges vary by age, with higher values in pediatric populations and a gradual decline with advancing age. Each laboratory should establish its own reference intervals based on instrument, reagents, and local population.N/A
No special patient preparation required. Fasting is not necessary. Patients should be well-hydrated. Recent blood transfusions, immunosuppressive therapy, chemotherapy, radiation, corticosteroid use, or hematopoietic stem cell transplantation may significantly affect results and should be documented.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CD3 Cells
Frequently asked questions
How Does This Test Help My Doctor?
How Often Should I Get This Test?
What Are Common Causes of Low CD3 Cell Counts?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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