A stable human platelet-white blood cell control for the Coulter Model S-Plus II

The preparation and evaluation of a human platelet-white blood cell control of at least 5 months' stability, as measured in the Coulter Counter Model S-Plus II, is described. In some preparations minor departures from log normal platelet (PLT) distributions were found, impeding the generation of values for mean PLT volume (MPV) and PLT distribution width (PDW). In many cases, however, excellent linearity for PLT and white blood cell (WBC) counts and low coefficients of variation for PLT and WBC counts and PDW were found. Some possible factors causing the large coefficient of variation found for MPV values are mentioned.