CD66 antigen (Leukocyte common antigen) by flow cytometry in peripheral blood cells
This test measures the presence of CD66 antigen, a protein found on the surface of certain white blood cells, using a blood sample. It helps identify and characterize immune cells.
["CD66a testing may assist in diagnosing or monitoring blood disorders or immune system conditions."]
Key facts at a glance
- LOINC
- 17184-3
- Short code
- CD66a
- Synonyms
- CD66a Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA) or ACD-A anticoagulated blood collection tube for flow cytometry
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Flow cytometry immunophenotyping using fluorescently labeled monoclonal antibodies against CD66a (BGP, CEACAM1)
- CPT
- 88184
- SNOMED
- 399143001
- Specimen volume
- 3-5 mL of whole blood; minimum 1 mL for pediatric or limited samples
- Stability
- Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). Refrigeration may affect cell viability for immunophenotyping.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
What Is CD66a Used For?
CD66 antigen (CD66a) is primarily used to identify and count certain white blood cells, including neutrophils, which are a type of immune cell. This can be helpful in diagnosing conditions like infections, inflammatory diseases, or blood disorders that affect white blood cell counts or function.
How Is the Sample Collected?
A small amount of blood is drawn from a vein, usually in your arm, using a needle. The blood sample is then processed in the lab to analyze the CD66 antigen on your white blood cells.
What Does a CD66a Test Tell You?
The test helps determine the proportion of CD66-positive cells in your blood. Elevated levels may indicate an infection, inflammation, or certain types of leukemia or lymphoma. Lower levels might suggest immune system suppression or other blood-related conditions.
When Might You Need This Test?
Your healthcare provider may recommend this test if you have symptoms like frequent infections, unexplained fevers, swollen lymph nodes, or if you are diagnosed with a suspected blood disorder. It can also be part of routine monitoring for patients with known immune or blood-related conditions.
Reference range
Reference ranges for CD66a-expressing cells are laboratory-specific and should be interpreted in clinical context. Results are typically reported as percentage of positive cells or absolute count per microliter.N/A
No special patient preparation required. Specimen should be collected prior to chemotherapy or other immunosuppressive therapy when possible for baseline assessment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD66a (Leukocyte common antigen) flow cytometry
Frequently asked questions
Why was I ordered a CD66a test?
What does a high or low CD66a level mean?
Do I need to prepare for this test?
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