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CD3+ T Cell Count (Peripheral Blood)

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

This test measures the number of CD3+ T cells in your blood, which are a type of white blood cell involved in immune responses. CD3+ T cells help your body fight infections and regulate immune reactions.

Quick summary

["CD3+ T cells are key players in your immune system—helping defend against pathogens and maintain balance."]

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

Key facts at a glance

LOINC
73902-9
Short code
CD3CD57
Synonyms
CD3-CD57+ Cells # Bld FC
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) blood collection tube; ACD (yellow-top) tube is also acceptable for flow cytometry analysis
Units
N/A
Ref low
60
Ref high
360
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
86359
SNOMED
399096003
Specimen volume
3-5 mL of whole blood (minimum 1 mL for pediatric samples)
Stability
Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). If processing is delayed beyond 24 hours, store at 2-8°C and process within 48 hours. Do not freeze.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why This Test Is Done

Doctors may order a CD3+ T cell count to evaluate immune function, diagnose or monitor conditions like immune deficiencies, autoimmune diseases, or certain cancers (e.g., lymphoma, leukemia). It can also help assess responses to treatments that affect the immune system.

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) to draw a blood sample. The process is quick and typically painless. If you’re nervous, let your healthcare provider know—they can offer comfort measures.

What the Results Mean

Results show the count of CD3+ T cells per microliter of blood. Low counts may indicate immune suppression, while very high counts could signal overactive immune responses or certain disorders. Your doctor will interpret results in the context of your overall health and medical history.

Common Conditions Affecting Results

Changes in CD3+ T cell counts can occur with conditions like HIV/AIDS (where immune cells decline), certain cancers (e.g., T-cell lymphomas), or treatments like chemotherapy or radiation that suppress the immune system. Autoimmune diseases (e.g., lupus) may also influence these levels.

Reference range

60-360 cells/μL (varies by laboratory; reference range should be established by each laboratory based on its own population and methodology)N/A

Specimen: whole-blood

No special preparation required. Patient should be well-hydrated. Inform the laboratory of any recent blood transfusions, immunosuppressive therapy, or immunotherapy, as these may affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal CD3+ T cell counts can signal underlying immune dysfunction, guide treatment decisions for immune-related disorders, or help monitor the effectiveness of therapies targeting the immune system. For example, low counts may prompt evaluation for infections or immune deficiencies, while elevated counts could warrant further investigation into overactive immune responses.

Short name

CD3+ T Cells

Frequently asked questions

What does a low CD3+ T cell count mean?
A low count may suggest weakened immune function, potentially due to infections (like HIV), certain cancers, or treatments that suppress immune cells. Your doctor will review your symptoms and other test results to determine the cause and next steps.
Can diet or lifestyle affect CD3+ T cell counts?
While diet and lifestyle can influence overall immune health, they rarely directly affect CD3+ T cell counts. Focus on a balanced diet, hydration, and avoiding smoking or excessive alcohol to support immune function, but this test measures specific immune cells rather than general health trends.
How often will I need this test?
Frequency depends on your medical condition and treatment plan. Some patients may need this test monthly, quarterly, or annually, while others may only need it once or twice a year. Your doctor will outline the schedule based on 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