B-Cell CD20 Expression

Casandra

Casandra Test Code LC75465Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 096930CPT Codes 86355, 86356

B-Cell CD20 Expression

Also known as: % CD20 B Lymphocytes, CD20, CD20 on B Lymphocytes

Clinical Use

Order Test

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.

Special Instructions

Not provided.

Limitations

Timing and consistency in the timing of blood collection are critical for monitoring patients for lymphocyte subsets. The test performance characteristics have been determined by Labcorp and it is performed in a CLIA certified laboratory for clinical purposes. However, it is not cleared or approved by the FDA. Monoclonal antibody-based therapies may block available CD20-binding sites, which can affect recognition by the assay. The concurrent use of CD19 markers provides additional insights on B-cell depletion with this assay.

Test Details

Methodology

Cell-based / Cytometry (Flow Cytometry)

Biomarkers

CD20

Protein

% CD19+CD20+ Cells

Expression • Ordinal Score (e.g., TPS, CPS, H-score)

CD20

Protein

% CD20+ B Cells

Expression • Ordinal Score (e.g., TPS, CPS, H-score)

LOINC Codes

Order Codes

94689-7 - CD20 Cells/Cells.CD19 NFr Bld

Result Codes

8117-4 - CD19 Cells NFr Bld
8119-0 - CD20 Cells NFr Bld

Result Turnaround Time

3-4 days

Specimen

Whole Blood

Volume

Fill tube(s) to capacity

Minimum Volume

0.5 mL

Container

Yellow-top (ACD) tube or lavender-top (EDTA) tube

Collection Instructions

Invert tube 8 to 10 times immediately after collection. To preserve cellular viability, collect specimen so it will arrive in the laboratory within 72 hours of collection. Indicate date and time of venipuncture on the tube(s) and on the test request form.