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Laboratory: Clinical Immunology
Test Name:
Test Code: PBLS
Clinical Information:
Assessing relative and absolute counts of T, B and NK Cells in any clinical context, including diagnosis and follow-up of primary immunodeficiencies, Immune monitoring following immunosuppressive therapy, and assessment of immune reconstitution post hematopoietic cell transplantation.

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 the progressive increase in CD4 T-cell count throughout the day while CD8 T-cells and 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 Handing: 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.

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
Reference Values:
2 day TAT. Note under Clinical Information/Diagnosis if patient is on Monoclonal Antibody Therapy.
See Also:
More Information:
If only CD19 and CD20 B Cell enumeration is required, order PB20 only: