B-cell Lymphocyte Count (Absolute)
This test measures the number of B cells, a type of white blood cell important for producing antibodies to fight infections.
["B cells help your immune system defend against bacteria and viruses by creating antibodies."]
Key facts at a glance
- LOINC
- 51356-4
- Short code
- CD19CD58
- Synonyms
- CD19+CD58+ Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) tube, ACD (yellow-top) tube, or sodium heparin (green-top) tube specifically validated for flow cytometry. Dedicated tube recommended; specimen should not be shared with CBC analysis when flow cytometric enumeration is required.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 1–99 years
- Method
- Flow cytometry using fluorescence-activated cell sorting (FACS) with monoclonal antibodies against CD19 and CD58 surface markers. Whole blood is stained with fluorochrome-conjugated antibodies, incubated, lysed, and analyzed on a flow cytometer to quantify CD19+CD58+ B-lymphocyte populations.
- CPT
- 86356 (Mononuclear cell antigen, quantitative, not otherwise specified) or 86359 (T-cells, total count); may also be reported under 88184-88185 (flow cytometry) with appropriate multiple unit billing.
- SNOMED
- 1421000119104 |Measurement of CD19+CD58+ cells in blood specimen|
- Specimen volume
- 3-5 mL of whole blood for adults; minimum 1 mL for pediatric patients. For young children or infants, microtainer collection (0.5-1 mL) may be acceptable depending on laboratory validation.
- Stability
- Specimen must be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Refrigeration (2-8°C) may extend viability up to 48-72 hours but can affect certain surface markers. Do not freeze. Specimen integrity should be confirmed by viability dye (e.g., 7-AAD) with target viability ≥85%.
- Hemolysis max
- 100
- Lipemia max
- 300
- Icterus max
- 40
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test to evaluate your immune system, check for infections, monitor conditions like chronic lymphocytic leukemia (CLL), or assess immune responses before treatments like chemotherapy or vaccines. It can also help diagnose autoimmune diseases or monitor immune-related side effects from medications.
What to Expect Before the Test
No special preparation is needed. This test is typically done by drawing blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. If you’re on blood-thinning medication, let your doctor know before the test.
What the Results Mean
Results show the absolute number of B cells in your blood. Low levels may indicate immune deficiencies, infections, or certain cancers like CLL. High levels could suggest overactive immune responses, autoimmune conditions, or certain blood disorders. Your doctor will interpret results in the context of your overall health and symptoms.
Common Conditions Affecting Results
Conditions that might affect B-cell counts include chronic infections, certain cancers (like lymphoma), autoimmune diseases (e.g., rheumatoid arthritis), or treatments that weaken the immune system (e.g., chemotherapy). Chronic diseases like HIV or long-term steroid use can also influence these levels.
Reference range
Reference ranges for CD19+CD58+ cells in peripheral blood vary by laboratory and must be interpreted in conjunction with total CD19+ B-cell counts. Generally, CD58 expression on CD19+ B-lymphocytes represents a small subpopulation; values should be compared against laboratory-established age-matched reference intervals and reported as both percentage of CD19+ cells and absolute count.N/A
No special fasting or dietary restrictions are required. Patients should be well-hydrated. Avoid recent corticosteroid therapy when possible, as it may transiently alter lymphocyte subset distribution. Recent vaccinations (particularly live vaccines) within 7-14 days may transiently affect lymphocyte populations.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low B-cell counts can indicate weakened immunity, making you more susceptible to infections. High counts may signal immune overactivity, which can cause inflammation or autoimmune reactions. Monitoring B-cell levels helps doctors diagnose and manage conditions like immunodeficiency, leukemia, or immune-related disorders, guiding treatment decisions such as adjusting medications or starting therapies to restore balance.
Short name
B-Cell Count
Frequently asked questions
How often is this test done?
What does a low or high B-cell count mean?
Can lifestyle changes affect B-cell counts?
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 10, 2026. · Read our editorial policy