WHITE CELL SUBSETS IN APHERESIS AND FILTERED PLATELET CONCENTRATES

BACKGROUND: White cell (WBC)-reduced platelet concentrates (PCs) are d efined by their absolute WBC count, a criterion which provides no info rmation regarding the various WBC subsets contained in the PC. These h eterogeneous cells are known to mediate different physiologic and path ophysiologic functions and account for distinct adverse transfusion re sponses.This study describes a method which allows the detection and q uantification of these subsets and characterizes their presence in a v ariety of platelet components. STUDY DESIGN AND METHODS: Random-donor pooled PCs (RD PCs) and single-donor apheresis PCs (SD PCs) were studi ed. RD PCs consisting of 6 units of 2- to 3-day old PCs were randomly assigned to be filtered with one of four WBC-reduction filters from th ree different manufacturers (n = 34). The residual WBCs were pelleted by centrifugation and isolated on a density gradient. The various WBC subsets were quantified by flow cytometry in unfiltered and filtered P Cs using fluorescence and two-angle light scatter. SD PCs obtained wit h two manufacturer's systems and three processing protocols (n = 30) w ere studied in like manner. RESULTS: WBC counts for non-WBC-reduced PC s averaged 3 x 10(8) in RD PCs and ranged from 8.6 to 9.6 x 10(6) per SD PC. Residual WBC counts in filtered PCs ranged from 2.3 x 10(4) to 2.2 x 10(5) and those in WBC-reduced SD PCs averaged 2.2 x 105 per uni t. The data demonstrate significant phenotypic differences among PCs p roduced with various procedures. All SD PCs and two of four filtered R D PCs contained five WBC populations including granulocytes and monocy tes, while RD PCs filtered with the remaining manufacturer's devices c ontained only lymphocytes. CONCLUSION: The data confirm that distinct phenotypic differences exist among PCs prepared with differ ent device s and/or procedures. It is suggested that as for non-generic pharmaceu ticals, the clinical benefits of these various PCs should be individua lly proved.