White cell subsets in apheresis and filtered platelet concentrates

Area of Science:

• Hematology
• Transfusion Medicine
• Cell Biology

Background:

• White cell (WBC)-reduced platelet concentrates (PCs) are defined by absolute WBC count, not specific WBC subsets.
• Heterogeneous WBC subsets in PCs mediate various physiological and pathophysiological functions, impacting transfusion responses.
• Current definitions lack information on the specific WBC subsets present in platelet components.

Purpose of the Study:

• To describe a method for detecting and quantifying WBC subsets in platelet components.
• To characterize the presence of these WBC subsets in various types of platelet concentrates.
• To compare WBC subset profiles in different platelet processing methods and devices.

Main Methods:

• Studied random-donor pooled PCs (RD PCs) and single-donor apheresis PCs (SD PCs).
• Utilized four WBC-reduction filters from three manufacturers for RD PCs (n=34).
• Quantified WBC subsets via flow cytometry in filtered and unfiltered PCs (RD and SD).

Main Results:

• Non-WBC-reduced PCs had high WBC counts (3 x 10^8 in RD PCs, 8.6-9.6 x 10^6 in SD PCs).
• Filtered PCs showed residual WBC counts from 2.3 x 10^4 to 2.2 x 10^5.
• Significant phenotypic differences in WBC subsets were observed across different PC preparations; some contained granulocytes and monocytes, others only lymphocytes.

Conclusions:

• Distinct phenotypic differences exist among PCs prepared with various devices and procedures.
• The clinical benefits of different PCs should be individually proven, similar to non-generic pharmaceuticals.
• Further research is needed to correlate WBC subset composition with clinical outcomes.