Effect of activation with fMLP on the adhesion of PMNs to fibrin. Neutrophils were perfused over fibrin-coated surfaces at shear stress 80 mPa after preactivation with different concentrations of fMLP (5 minutes at 37°C). (A) The total number of adhering PMNs per square millimeter was measured to pure fibrin (○) and plasma fibrin (•). The data represent the number of adhering neutrophils per square millimeter as a percentage of the (unstimulated) control. Absolute control values are 1,020 ± 56 cells/mm2 for pure fibrin and 921 ± 78 cells/mm2 for plasma fibrin. *A significant effect of fMLP activation was determined for both surfaces by repeated measures ANOVA (P < .05). (B) During the experiments, the cluster index of the cells adhered to pure fibrin (○) was determined as well. The mean values ± SE of four to six experiments are given. *A significant effect of fMLP activation was determined by repeated measures ANOVA (P < .05).