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Labcorp Oklahoma, Inc.
Test Directory


B-Cell CD19/CD20 Expression

Order Name CD19/CD20
Test Number: 0114175
Revision Date 05/23/2023
Test Name Methodology LOINC Code
CD19 Percent
Flow cytometry 8117-4 
CD20 Percent
Flow cytometry 8119-0 
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 5 mL each (0.5 each) Whole Blood EDTA (Lavender) and ACD Sol A/B (Yellow Top) Room Temperature
Instructions Collect Whole Blood in Both EDTA (lavendar top) and ACD Solution A or B (yellow top) 
Deliver to the laboratory ASAP - Same Day as Collection!
DO NOT Centrifuge or Refrigerate. Keep Whole Blood.  Collect Monday through Wednesday only!
Specimen must be received at Labcorp Oklahoma Inc. by Wednesday afternoon or collect sample on Monday.
Specimen stability: 4 days Room Temperature.
Expected TAT 3-5 days, testing schedule may vary  
Clinical Use This test can be used in assessing therapeutic B-cell depletion in any clinical context, including Multiple Sclerosis, malignancies, autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus and membranous glomerulonephritis among others, and treatment or prevention of acute humoral rejection in positive crossmatch renal transplant recipients. It can be used in the evaluation of CD20 deficiency in patients with suspected CD19 deficiency (humoral immunodeficiency), and it can be used to confirm the complete absence of B cells in suspected primary humoral immunodeficiencies using both CD19 and CD20 markers.
Monoclonal antibody-based therapies block available CD20-binding sites and, therefore, the antibody used for this flow cytometric assay cannot recognize the CD20 molecule on B cells. The concomitant use of the CD19 marker provides information on the extent of B-cell depletion when using this particular treatment strategy. This Flow Cytometry panel is also useful for confirming the complete absence of B cells in suspected primary humoral immunodeficiencies. 
Performing Labcorp Test Code 096930 
Notes This is Performed at Labcorp America
CPT Code(s) 86355, 86356
Lab Section Reference Lab