B-cell CD19 Kappa Light Chain Ratio in Whole Blood (Flow Cytometry)
This test measures the proportion of B cells expressing kappa light chains in your blood, which can help assess immune cell health or detect abnormalities like monoclonal gammopathies.
["This test helps evaluate immune system function and potential blood disorders."]
Key facts at a glance
- LOINC
- 17122-3
- Short code
- CD19KAP
- Synonyms
- CD19+Kappa+ Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) vacutainer tube, sterile; sodium heparin (green-top) may also be acceptable for flow cytometry applications.
- Units
- N/A
- Ref low
- 60
- Ref high
- 80
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Flow cytometry using fluorescein isothiocyanate (FITC)-conjugated anti-kappa light chain antibody combined with phycoerythrin (PE)-conjugated anti-CD19 monoclonal antibody; whole blood is incubated with antibodies, red cells lysed, and CD19+/kappa+ B-lymphocytes enumerated on a flow cytometer with CD45/SSC gating to isolate the lymphocyte population.
- CPT
- 86355
- SNOMED
- 116646007
- Specimen volume
- 3–5 mL of whole blood (minimum 1 mL for pediatric samples); sufficient volume to accommodate antibody panels and viability testing.
- Stability
- Specimen should be processed within 24–48 hours of collection when stored at room temperature (20–25 °C); do not refrigerate as cold exposure may cause loss of surface immunoglobulin and CD marker expression. Specimens exceeding 48 hours post-collection should be rejected.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
What This Test Measures
The test identifies and quantifies B cells that have kappa light chains—a component of antibodies—using a specialized blood sample analysis. It compares the ratio of kappa to lambda light chains on CD19-positive cells, which are markers of B-cell maturity.
Why It’s Done
Your healthcare provider may order this test if you have symptoms of immune disorders, unexplained fatigue, or if tests suggest an abnormal immune response. It can also be part of diagnosing conditions like multiple myeloma or other monoclonal gammopathies.
Sample Collection
A small blood sample is drawn from a vein, typically in your arm. The blood is processed to isolate B cells and analyze their light chain composition.
Preparation and Testing
No special preparation is needed. The blood sample is sent to a lab where flow cytometry is used to detect and count CD19-positive cells with kappa light chains. The results are expressed as a ratio compared to a standard.
Reference range
CD19+ B cells expressing surface kappa light chains typically represent 60–80% of total circulating CD19+ B-lymphocytes in healthy adults (kappa:lambda ratio approximately 1.0–2.5:1). Absolute CD19+/kappa+ counts should be interpreted in conjunction with CD19+/lambda+ and total CD19+ cell counts to evaluate clonality.N/A
No fasting is required. Patients should be well-hydrated. Recent corticosteroid therapy, chemotherapy, immunotherapy (e.g., rituximab), or radiation therapy may transiently alter B-cell counts and should be documented at the time of collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal ratios may indicate clonal B-cell proliferation, which can be associated with conditions like multiple myeloma, chronic lymphocytic leukemia, or other hematologic malignancies. It’s not a standalone diagnostic test but can support broader evaluations.
Short name
CD19 Kappa Light Chain Ratio
Frequently asked questions
Why might I need this test?
What do the results mean?
How long does it take to get results?
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 16, 2026. · Read our editorial policy