CD8 T-Cell Count (Peripheral Blood)
This test measures the number of CD8+ T cells, a type of immune cell that helps fight infections and cancer by targeting virus-infected cells and tumor cells.
["CD8+ T cells play a key role in your immune response—understanding their levels can help identify immune function or potential health concerns."]
Key facts at a glance
- LOINC
- 47019-5
- Short code
- CD8IHC
- Synonyms
- CD8 Ag Tiss Ql ImStn
- Category
- chemistry
- Sample
- serum
- Container
- 10% neutral buffered formalin container for tissue fixation
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- immune-stain
- CPT
- 88342
- SNOMED
- 399375002
- Specimen volume
- Tissue biopsy or surgical specimen of adequate size (minimum 3-5 mm) placed in formalin
- Stability
- Tissue in 10% neutral buffered formalin: stable at room temperature (15-25°C) indefinitely; paraffin-embedded blocks stable at room temperature for years; cut sections on slides stable for 1-2 years at room temperature
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order this test to evaluate your immune system, monitor conditions like HIV, check for immune deficiencies, or assess responses to treatments such as cancer therapies (e.g., immunotherapy). It can also help diagnose or track diseases like autoimmune disorders or infections.
How the Test Works
A small blood sample is taken, typically from your arm. The sample is analyzed using a technique called flow cytometry, which identifies and counts specific immune cells based on their unique surface markers, including CD8.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to avoid certain medications (like steroids) that could affect immune cell counts. If you’re on blood-thinning medication, let your provider know before the test.
What to Expect During the Test
The test involves a quick, painless blood draw. You may feel a slight pinch, but it’s over quickly. The blood is then sent to a lab for analysis, and results are typically available within a few days.
Reference range
Reported as Positive or Negative for CD8 antigen expression in tissue; semi-quantitative scoring may include percentage of positive cells and staining intensity (weak, moderate, strong)N/A
No special patient preparation required for the tissue specimen; surgical or biopsy tissue is obtained by the performing physician
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CD8+ T-Cell Count
Frequently asked questions
What Does a Low or High CD8+ T-Cell Count Mean?
How Might My Results Affect My Treatment?
Can I Get My CD8+ T-Cell Count at Home?
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