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CD8+ T Cell Count (Peripheral Blood)

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

This test measures the number of CD8+ T cells, a type of white blood cell important for fighting infections and cancer.

Quick summary

["CD8+ T cells help your immune system target and destroy harmful cells."]

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

Key facts at a glance

LOINC
38242-4
Short code
CD8CD95
Synonyms
CD8+CD95+ Cells NFr Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) or ACD (yellow-top) anticoagulated blood collection tube. Heparinized tubes (green-top) may be acceptable for some flow cytometry protocols
Units
N/A
Ref low
5
Ref high
20
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD8 and CD95 surface markers, with enumeration by multiparameter analysis
CPT
86359 (T cells, total count); additional 86361 or 86360 may apply depending on panel composition
SNOMED
269829007 | 44241006
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric patients
Stability
Process within 24-48 hours of collection when stored at room temperature (18-25°C). Do not refrigerate. Viability of lymphocytes decreases significantly after 48 hours, leading to inaccurate CD95 expression assessment
Hemolysis max
100
Lipemia max
300
Icterus max
50
TAT
4–48 hours
Order
routine

What Is CD8+ T Cell Count Used For?

Doctors may order this test to evaluate immune function, monitor immune-related conditions (such as HIV or certain cancers), or assess responses to treatments like chemotherapy or immunotherapy. It can also help diagnose or monitor autoimmune diseases or infections.

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The sample is sent to a lab for analysis.

What Does a Low or High Count Mean?

A low CD8+ T cell count may indicate weakened immune function, which can happen with certain infections, immune disorders, or treatments like chemotherapy. A high count could suggest an overactive immune response or certain immune-related conditions.

How Long Does It Take to Get Results?

Results are typically available within 1–3 business days, depending on lab processing times. Your healthcare provider will discuss the results with you.

Reference range

Reference values vary by laboratory and population; CD8+CD95+ cells are typically reported as a percentage of total lymphocytes or as absolute count (cells/μL). Typical adult range: 5-20% of CD8+ T cells; absolute count approximately 100-400 cells/μLN/A

Specimen: whole-blood

No fasting required. Avoid strenuous exercise prior to collection. Specimen should be collected before administration of immunosuppressive therapy when possible. Inform laboratory of recent vaccinations, infections, or immunomodulatory medications

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: CD8+ T cells play a critical role in immune surveillance, particularly against viruses and tumors. Abnormal counts can signal immune dysfunction, chronic illness, or treatment effects, guiding further medical evaluation.

Short name

CD8+ T Cell Count

Frequently asked questions

Why might my doctor order this test?
Your doctor may recommend this test if you have symptoms of immune issues, are undergoing cancer treatment, have an infection, or if monitoring an existing condition like HIV or an autoimmune disease.
What should I do if my CD8+ T cell count is abnormal?
Follow your doctor’s instructions for next steps. They may recommend additional tests, adjustments to treatment, or lifestyle changes to support your immune health.
Does diet or supplements affect CD8+ T cell counts?
While diet and supplements can influence overall immune function, they do not directly alter CD8+ T cell counts. Focus on a balanced diet and avoid excessive stress or smoking, which may impact immune health.
  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