Tumor-Infiltrating Lymphocyte Count (TIL)
This test measures the number of immune cells (lymphocytes) found inside cancer cells in a tissue sample. It helps doctors assess how the tumor’s immune response might affect treatment and prognosis.
["TIL counts can guide personalized cancer care and inform decisions about immunotherapy."]
Key facts at a glance
- LOINC
- 44693-0
- Short code
- Tumor infiltrating lymph
- Synonyms
- Tumor infiltrating lymph
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 7.35
- Ref high
- 7.45
- Critical range
- 7.2 N/A – 7.6 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Doctors may order a TIL test if you have certain types of cancer, such as melanoma or some lung cancers, where immune cells inside the tumor are studied to understand how your body’s immune system interacts with the cancer. It’s often used alongside other tests to help plan treatment, including immunotherapy.
How Is the Sample Collected?
A small sample of your tumor tissue is taken during surgery or a biopsy. The lab processes this tissue to count the immune cells (lymphocytes) inside the cancer cells. This is not done on blood or other body fluids but specifically on the tumor tissue itself.
What Does a TIL Test Tell You?
Higher TIL counts may suggest a stronger immune response against the cancer, which could mean better outcomes with certain treatments like immunotherapy. Lower counts might indicate a weaker immune reaction, which could influence treatment choices.
What Are Possible Results?
Results are typically reported as a count of lymphocytes per high-power field (HPF) or as a percentage of tumor cells. There are no standard reference ranges because this test is highly specific to the tumor type and individual patient needs.
Reference range
NCBI: pH 7.35-7.45N/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
TIL Count
Frequently asked questions
What does a TIL test measure?
How is the TIL test different from a blood test?
Can a TIL test replace other cancer tests?
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.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy