CD8+ T-Cell Count (Peripheral Blood)
This test measures the number of CD8+ T-cells, a type of white blood cell important for fighting viruses and cancer. CD8+ T-cells help regulate immune responses by targeting infected or abnormal cells.
["CD8+ T-cells help protect your body from infections and cancer; low levels may signal immune dysfunction."]
Key facts at a glance
- LOINC
- 73898-9
- Short code
- CD8CD57
- Synonyms
- CD8-CD57+ Cells/lymph NFr Bld FC
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA) tube or specialized flow cytometry tube (sodium heparin acceptable)
- Units
- N/A
- Ref low
- 2
- Ref high
- 15
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- flow-cytometry
- CPT
- 86356
- SNOMED
- 269809004
- Specimen volume
- 3-5 mL whole blood; minimum 1 mL for pediatric samples
- Stability
- Stable for 24-48 hours at room temperature (18-25°C); process within 24 hours for optimal viability; do not refrigerate
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test to evaluate immune function, diagnose conditions like HIV/AIDS, monitor immune suppression (e.g., after organ transplant), or assess immune-related diseases such as certain cancers or autoimmune disorders.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. The process usually takes a few minutes, and you may feel a brief pinch or discomfort.
How the Test Works
Blood is collected and analyzed to count CD8+ T-cells using flow cytometry, a precise method that identifies and measures specific immune cell types.
What the Results Mean
Results are expressed as a count of CD8+ T-cells per microliter of blood. Lower than expected levels may indicate immune suppression, while higher levels could be associated with certain immune conditions or infections.
Reference range
Typically 2-15% of total lymphocytes or 50-400 cells/μL; reference ranges vary by laboratory and populationN/A
No special preparation required. Avoid exercise prior to collection as it may transiently alter lymphocyte subset distribution.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD8 Lymphocyte Count
Frequently asked questions
What does a low CD8+ T-cell count mean?
How often should I get this test?
Can diet or lifestyle affect CD8+ T-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