Lab Information Manual

Laboratory:

Clinical Immunology

Test Name:

CD20 B-Cell Enumeration - (B)

Test Code: PB20

Clinical Information:

Assessing therapeutic B-cell depletion quantitatively (absolute counts of cells/mcL) in any clinical context, including 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.

The absolute counts of lymphocyte subsets are known to be influenced by a variety of biological factors, including hormones, the environment, and temperature. The studies on diurnal (circadian) variation in lymphocyte counts have demonstrated that CD19+ B cells increase between 8:30 am and noon, with no change between noon and afternoon. Timing and consistency in timing of blood collection is critical when serially monitoring patients for lymphocyte subsets.

Collection Devices:

Preferred Device:	1 - EDTA 4 mL NO GEL Tube(s) - Full Tube Collection
Alternate Device:	1 - Microtainer(s) - EDTA, NO GEL (0.5 mL) to fill line

Specimen Required:

Blood: 4.0 mL

Pediatric Blood: 0.5 mL

A CBC must also be performed.

Specimen Handling: Samples will be rejected if received frozen, greater than 48 hours old, clotted, or hemolyzed. Samples will not have absolute counts reported if a CBC is not provided and cannot be performed within 24 hours of collection.

Referral:

Send specimens in original tube. DO NOT ALIQUOT.

Specimens are required to be received in the laboratory weekdays and by 4 p.m. on Friday. It is recommended that specimen be received in laboratory within 24 hours. Draw and package specimen as close to shipping time as possible.
Sample must be shipped at ambient temperature.
Samples arriving on the weekend may be cancelled

Requisition:

_SH Flow Cytometry Laboratory Requisition (R250-10-82)

Reference Values:

Age             %CD19+    CD19+ cells   %CD19+CD20+    CD19+CD20+ cells
0-2 years          1-34        24-2149            1-33                        24-2086
3-17 years         6-33        110-1400           5-32                        92-1357
≥18 years          4-25       79-574              3-24                        59-551

Availability:

Weekdays

2 day TAT. Note under Clinical Information/Diagnosis that patient is on Monoclonal Antibody Therapy.