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: CD19+ Lambda Light Chain-Expressing B Cells in Whole Blood

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

: This test measures a specific subset of B cells in a blood sample: those that carry the CD19 marker and express lambda-type light chains on their surface. It is used mainly in the evaluation of certain blood and immune system conditions.

Quick summary

[": It counts a specialized group of antibody-producing white blood cells to help classify B-cell disorders."]

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

Key facts at a glance

LOINC
50665-9
Short code
CD19LAM
Synonyms
CD19+Lambda+ Cells # Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) tube for flow cytometry; heparinized tube may also be acceptable. Dedicated flow cytometry tubes preferred.
Units
N/A
Ref low
1
Ref high
2
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow Cytometry (Immunophenotyping) using fluorescently-labeled monoclonal antibodies against CD19 and surface immunoglobulin lambda light chains
CPT
86356 (Flow cytometry, cell surface, tumor-associated antigen, technical component only); 88184-88185 for additional markers may apply; 86355 for B-cell enumeration
SNOMED
439953004 | B lymphocytes - Leucocyte|; 39754003 |Lambda light chains|
Specimen volume
3-5 mL of whole blood in EDTA tube; minimum 1 mL for pediatric samples
Stability
Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Do not refrigerate for flow cytometry analysis as this may affect cell viability and surface antigen expression.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

: What Is Being Measured

: B cells are a type of white blood cell that make antibodies, and each B cell displays antibody molecules on its surface. Every antibody has two light chains, called kappa or lambda. This test identifies B cells that have the CD19 surface marker and carry lambda light chains, using a laboratory technique such as flow cytometry.

: Why This Test Is Done

: Doctors order this test when they suspect an abnormal buildup or loss of B cells, such as in certain lymphomas, leukemias, or immune deficiency conditions. Looking at the balance of kappa- and lambda-bearing B cells can help show whether one group of cells is growing out of control.

: How the Sample Is Collected

: A small blood sample is drawn from a vein, usually in your arm. The sample is treated with special marker molecules that attach to CD19 and to lambda light chains so the laboratory can identify and count the cells.

: What the Results Can Mean

: Results describe the proportion or number of these cells compared with other B cells. A normal balance suggests a polyclonal (many different) population, while a marked excess of lambda-bearing cells can suggest a clonal (single-lineage) process. Your doctor interprets this alongside other tests and your symptoms; specific ranges vary by laboratory.

Reference range

Reference ranges for CD19+ Lambda+ cells vary by laboratory and age. Generally, lambda-positive B cells represent approximately 0.4%-0.8% of total lymphocytes or about 40%-60% of total kappa+lambda B cells. Normal kappa:lambda ratio is approximately 1.0-2.0 (typically 1.5 ± 0.5). Absolute counts should be interpreted alongside total B-cell count and kappa:lambda ratio.N/A

Specimen: whole-blood

No special patient preparation required. Recent corticosteroid therapy, chemotherapy, immunosuppressive medications, or rituximab treatment may significantly affect results and should be documented.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

: This test helps clinicians distinguish a normal, varied B-cell population from an abnormal expansion of one B-cell type, which is important in diagnosing and monitoring B-cell lymphomas, leukemias, and some immune disorders. It is rarely used alone and is interpreted together with other flow cytometry markers and clinical findings.

Short name

: CD19 Lambda B Cells, Blood

Frequently asked questions

: Does this test diagnose cancer by itself?
: No. It provides one piece of information about your B cells. A diagnosis requires combining these results with other laboratory tests, imaging, and sometimes a tissue biopsy, all reviewed by your doctor.
: Do I need to fast before this test?
: Fasting is generally not required for this type of blood cell analysis, but follow any instructions your ordering provider gives you, since other tests drawn at the same time may have different requirements.
: Can medicines or illness affect the results?
: Yes. Some medications, recent infections, and other health conditions can change B-cell populations, so tell your doctor about all medicines you take and any recent illness before the test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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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