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B-cell CD19 Kappa Light Chain Positive Cells (Absolute Count)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of B cells that express the CD19 marker and produce kappa light chains in your blood. It may be used to assess immune function or monitor conditions affecting B cells.

Quick summary

["This test helps evaluate immune health or diagnose certain blood disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
26565-2
Short code
CD19K
Synonyms
CD19+Kappa+ Cells NFr Spec
Category
chemistry
Sample
serum
Container
EDTA (lavender-top) tube for peripheral blood; sterile collection container for bone marrow or other tissue specimens
Units
N/A
Ref low
0.5
Ref high
2
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry immunophenotyping using fluorescently labeled antibodies against CD19 surface marker and kappa light chain
CPT
86356
SNOMED
269809005
Specimen volume
1-3 mL of peripheral blood in EDTA tube; minimum 0.5 mL for pediatric samples
Stability
Specimen should be processed within 24-48 hours of collection. Store at room temperature (18-25°C). Do not refrigerate or freeze as this may affect cell viability and surface marker expression.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

What Does This Test Measure?

The test identifies a specific subset of white blood cells (B cells) that have markers (CD19) and light chains (kappa) on their surface. These cells are part of the immune system and play a role in producing antibodies. The absolute count reflects the proportion of these cells in your bloodstream.

Why Might This Test Be Ordered?

Your healthcare provider may order this test if you have symptoms or conditions that could involve abnormal B-cell activity, such as certain autoimmune diseases, infections, or blood disorders. It may also be part of a broader immune evaluation.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate the cells, and the test measures the specific subset of B cells as described. No special preparation is needed, but fasting may not be required unless specified by your provider.

What Are Possible Results?

Results are expressed as the absolute number of CD19+ kappa light chain-positive B cells per microliter (µL) of blood. Interpretation depends on clinical context, including your overall health and symptoms. Your healthcare provider will discuss these results with you.

Reference range

CD19+ B-cells with kappa light chain restriction are interpreted in the context of total B-cell count and kappa/lambda ratio. Normal kappa/lambda ratio is approximately 0.5-2.0 in polyclonal B-cell populations. Reference ranges vary by laboratory; results should be interpreted alongside total CD19+ B-cell count.N/A

Specimen: serum

No special patient preparation required. Recent corticosteroid therapy, chemotherapy, or immunosuppressive medications may affect B-cell counts and should be documented.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CD19+ Kappa Light Chain+ B Cells

Frequently asked questions

How is this test different from a general B-cell count?
This test specifically targets B cells that express both CD19 and kappa light chains, which narrows the focus to a subset of B cells. A general B-cell count includes all B cells, regardless of light chain type or other markers.
What conditions might affect this test result?
Conditions affecting overall B-cell counts (e.g., infections, chemotherapy, or immune disorders) may indirectly influence this test. Chronic diseases, medications (like steroids), or recent vaccinations could also impact immune cell populations.
Can this test be done at home?
No, this test requires a blood sample collected by a healthcare professional in a clinical setting. Home blood tests typically do not provide this level of specificity.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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