Overview of the study design and data types. (A) Schematic diagram of the analyses; gray blocks represent distinct analyses, which are grouped row-wise according to the data set to which they were applied; the arrows illustrate the flow of information between analyses; the colors in the embedded strips indicate the nature of the primary data used for each analysis. (B) Examples of histograms of log fluorescence intensity from the FC measurements used to quantify PR; the left and right hand panels show measurements of fluorescence generated by an anti-human fibrinogen polyclonal antibody that labels bound fibrinogen and an anti–P-selectin monoclonal antibody, respectively; the upper and lower panels correspond to an individual with a high (red) and an individual with a low (blue) PR, respectively; the filled histograms represent the distributions of log intensity measurements from activated platelets (using the agonist ADP, in this example) incubated with a labeled antifibrinogen antibody or a labeled anti-P-selectin antibody, whereas the open histograms represent negative controls (“Methods”); the dotted lines correspond to the positivity thresholds (ie, to the 98% quantiles of the distributions illustrated by the open histograms); the percentages of agonist-treated platelets that exceed the positivity thresholds are shown. (C) Composite of the 2 CBC scattergrams measured from blood taken from the 2 individuals in panel B, which are distinguished using colors, as in panel B.