African American control (AA) or steady -state sickle cell disease (SS) human whole blood with or without LPS pretreatment and with or without addition of a cocktail of P-selectin and Mac-1 function-blocking mAbs was perfused through micro-channels presenting P-selectin, ICAM-1, and IL-8; and neutrophil-platelet interactions were monitored in a field of view (FOV) using quantitative microfluidic fluorescence microscopy (qMFM) over a 2-minute period. LPS was added to the blood and incubated at room temperature for 10 minutes before perfusion through the micro-channels. Flow was stopped after 2 minutes of perfusion, and function-blocking antibodies were added to the blood. Flow was resumed, and observations were made for another 2 minutes. (A and B) Effect of simultaneous inhibition of platelet P-selectin and neutrophil Mac-1 on (A) total platelet interactions with arrested neutrophils and (B) number of platelet interaction events per arrested neutrophil in control or SCD human blood with or without pretreatment with LPS (0.25 or 1 μg/ml). *P < 0.05 when compared with baseline; ^#P < 0.05 when comparing control with SCD; ⁺P < 0.05 when comparing LPS with Ab treatment. Representative of 8 experiments with 4 control and 4 SCD subjects. (C and D) No effect of isotype IgG₁ control Ab treatment on the total number of platelet interactions with arrested neutrophils in (C) 1 μg/ml LPS–treated control and (D) 0.25 μg/ml LPS–treated SCD human blood. Representative of 5 experiments done with 2 control and 3 SCD subjects. Data represent mean ± SEM. Means were compared using Student’s t test with Bonferroni correction for multiple comparisons. Each data point represents a single field of view (FOV), and observations were made over multiple FOVs in individual experiments. See Supplemental Methods for details. Wall shear stress: 6 dyn/cm². FOV: ~14,520 μm².