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CD3+ T Cell Count (Absolute)

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

This test measures the number of CD3+ T cells in your blood, which are a key type of white blood cell involved in immune responses.

Quick summary

["CD3+ T cells help fight infections and regulate immune function."]

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

Key facts at a glance

LOINC
73903-7
Short code
CD3CD57
Synonyms
CD3-CD57+ Cells NFr Bld FC
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA) or sodium heparin (green-top) blood collection tube. Acid-citrate-dextrose (ACD) tubes are also acceptable for some flow cytometry assays.
Units
N/A
Ref low
2
Ref high
10
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
flow-cytometry
CPT
86359
SNOMED
399143005
Specimen volume
Minimum 2-3 mL of whole blood for adults; 1-2 mL for pediatric patients. Volume requirements may vary by laboratory protocol.
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 stability to 48-72 hours for some markers, but CD57 expression can be affected by prolonged storage. Best results are obtained when analysis is performed within 24 hours of collection.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

What Are CD3+ T Cells?

CD3+ T cells are a subset of white blood cells that play a central role in adaptive immunity. They recognize foreign antigens and trigger immune responses, including helping B cells produce antibodies and activating other immune cells like cytotoxic T cells. This test specifically counts these cells to assess overall immune health and detect abnormalities that may indicate immune disorders or deficiencies.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or signs of autoimmune conditions. It can also be used to monitor immune function in people undergoing treatments like chemotherapy or receiving immune-suppressing medications.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate the white blood cells, and the CD3+ T cells are counted using advanced laboratory techniques. This test is usually performed on whole blood.

What Does the Result Mean?

Results are reported as an absolute count of CD3+ T cells per microliter (cells/µL) of blood. While reference ranges can vary by lab, lower than expected counts may suggest immune deficiency, while higher counts could indicate overactive immune responses or certain conditions like chronic infections.

Reference range

Reference ranges are laboratory-specific and vary based on instrument platform, antibody clones, and gating strategies. Typical adult reference ranges for CD3-CD57+ cells as a percentage of leukocytes are approximately 2-10% (absolute count varies with total leukocyte count). Consult the performing laboratory's reference interval for specific values.N/A

Specimen: whole-blood

No special patient preparation is required. Fasting is not necessary. Patients should follow normal daily routines prior to specimen collection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CD3 Cells

Frequently asked questions

Could low CD3+ T cell counts affect my health?
Yes, low CD3+ T cell counts can weaken your immune system, making you more susceptible to infections. This may require further evaluation to determine the underlying cause, such as an autoimmune disorder, genetic condition, or side effects of certain medications.
What if my CD3+ T cell count is higher than normal?
Higher-than-normal CD3+ T cell counts may suggest an overactive immune response, chronic inflammation, or conditions like certain leukemias or lymphomas. Your doctor will discuss these findings with you and may recommend additional testing to explore possible causes.
How often should I get this test?
The frequency depends on your medical condition and treatment plan. If you have an ongoing health issue, your doctor may order this test periodically to monitor your immune status. Follow-up recommendations will be tailored to your specific needs.
  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