Understanding This Medical Test: What It Is, How It Is Performed, and Why You May Need It
This test measures the amount of LRBA protein on B cells in your blood using flow cytometry, helping diagnose conditions related to LRBA protein deficiency.
{"Measures LRBA protein levels on B cells (CD19+ cells)","Helps diagnose LRBA deficiency and related immune disorders","Involves analyzing a blood sample with specialized equipment","Results show mean fluorescence intensity (MFI) indicating protein quantity","Important for evaluating autoimmune conditions and immunodeficiencies"}
Key facts at a glance
- LOINC
- 100433-2
- Short code
- LRBA-MFI-CD19
- Synonyms
- B-cells LRBA MFI Bld FC
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA anticoagulant tube (preferred for immunophenotyping); ACD-A or sodium heparin tubes are acceptable alternatives. Sterile collection technique is essential to maintain cell viability.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- flow-cytometry
- CPT
- 88184
- SNOMED
- 444080009
- Specimen volume
- 2-5 mL of whole blood for adults; minimum 1 mL for pediatric patients. Volume requirements may vary by laboratory and instrument specifications.
- Stability
- Specimens should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Refrigeration (2-8°C) is generally not recommended for flow cytometry as it may affect cell viability and fluorescence intensity. Extended stability requires validation by the performing laboratory.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
This test is a diagnostic procedure that helps your healthcare provider learn more about your health. It can be used to check how well your body is functioning, look for signs of a medical condition, or gather information that guides decisions about your ongoing care.
The LRBA protein expression test is a specialized flow cytometry test that measures the amount of LRBA (LPS-responsive beige-like anchor) protein on the surface of B cells in your blood. B cells are identified by the CD19 marker. The test specifically examines cells that are CD3-negative (not T cells), CD14-negative (not monocytes), and CD19-positive (B cells). The result is reported as mean fluorescence intensity (MFI), which indicates how much LRBA protein is present on each cell.
How the test is performed depends on the type of test your provider has ordered. In many cases, a small sample of blood, urine, or other tissue is collected and sent to a laboratory for analysis. Other tests use imaging equipment or a physical examination at the bedside to collect the needed information.
A healthcare provider will collect a blood sample from a vein in your arm. The sample is then sent to a laboratory where flow cytometry is performed. In this technique, blood cells are passed through a laser beam, and fluorescent antibodies specific to LRBA protein and CD19 marker are used to detect and measure the protein levels. The machine measures the fluorescence intensity, which correlates with the amount of LRBA protein on the B cells.
Your provider may recommend this test to find the cause of symptoms you are having, to screen for a condition before it leads to problems, or to see how well a treatment is working. The results give your care team important information they can use to plan your diagnosis and treatment.
Your doctor may order this test if you have symptoms suggesting an immune system disorder, such as recurrent infections, autoimmune problems, or unexplained swelling of lymph nodes or spleen. It is particularly useful in evaluating conditions like Common Variable Immunodeficiency (CVID), Autoimmune Lymphoproliferative Syndrome (ALPS), and other disorders associated with LRBA deficiency.
Reference range
LRBA mean fluorescence intensity (MFI) in CD19+ B cells is reported as a relative quantitative value; reference ranges are laboratory-specific and should be established by each flow cytometry facility. Results are typically interpreted in the context of clinical findings and compared to internal control MFI values from healthy donors analyzed in parallel.N/A
No special patient preparation is required prior to specimen collection. Patients should follow standard phlebotomy protocols. Inform the laboratory of any recent immunosuppressive therapy, chemotherapy, or biologic agent administration as these may affect lymphocyte subset analysis.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before this test?
How long does it take to get results?
What do the results mean?
Is this test safe?
Sources
- 1
- 2
- 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