Inhibition of KKO-induced platelet accretion and fibrin generation by monocyte depletion and partial restoration by monocyte repletion. (A) Analysis of platelet accretion in the microfluidic system using human whole blood samples, blood samples after monocyte depletion, and samples repleted with monocytes isolated from a separate donor. All samples were run in parallel, stimulated with PF4 and KKO, and expressed relative to a whole blood control. Data are presented as the ratio of experimental to control conditions. Dotted line represents no stimulation or inhibition relative to whole blood sample. Mean ± 1 SEM is shown. N = 5 with samples from 3 donors. Paired Student t tests were used to compare depleted or repleted blood to the whole blood control. (B) Same as in (A), but for end point analysis of fibrin generation. n.s., not statistically significant comparing whole and repleted blood studies.