CD20 is a transmembrane, non-glycosylated protein expressed on B-cell precursors and mature B cells, but is lost following differentiation into plasma cells. In resting B cells, CD20 appears in a 33 kDa non-phosphorylated form. After mitogen stimulation, CD20 becomes heavily phosphorylated (35-37 kDa isoforms), and it is a dominant phosphoprotein in activated B cells. The antibody reacts with an intracytoplasmic epitope localized on the CD20 antigen and labels cells of the B-cell lineage. It is a useful tool for the classification of neoplasms of B-cell derivation.
A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type or one (1) unbaked, unstained slide cut at 4-5 microns for H&E staining (required) and two to three (2-3) positively charged unstained slides cut at 3-4 microns for each test/antibody ordered.
Storage and Transport
Use cold pack during transport of paraffin blocks and unstained slides. Cold pack should not be placed in direct contact with the specimen during shipping.
Specimen Rejection Criteria
All specimens must be submitted according to the test directory instructions. Before submitting specimen, please carefully review specimen requirements.
Listed below are possible causes for delays in specimen processing or possible specimen rejections or cancellations:
- No patient identification on requisition form
- No patient identification on specimen container or slides
- No referring provider
- No account information provided
- No test ordered on requisition
- No specimen source provided
- Inappropriate specimen type
- Insufficient volume for analysis
- Inappropriate specimen container
- Improper specimen transport
- Specimen leaked in transport
- Specimen submitted in incorrect or expired transport media
- Slides broken beyond repair on receipt
- Conflict between patient name on specimen and requisition form
- Specimen not properly preserved
- Sample containing a needle
A representative from Client Services will attempt to contact your office to resolve specimen problems. Additional documentation may be requested from your office to be returned by fax. In the event that resolution is not possible, the specimen may be returned to your office.
Turn Around Time (TAT)
88341, 88342, 88360