Platelets increase neutrophil adherence in vitro to nylon fiber

The effect of platelets on the adherence of neutrophils to nylon fiber was assessed in whole blood samples and purified neutrophil suspensions in the presence or absence of plasma. In whole blood samples, increasing numbers of platelets were associated (r = 0.47, p less than 0.02) with increasing adherence of neutrophils. Addition of platelets in plasma to purified neutrophil suspensions increased (p less than 0.05) neutrophil adherence from 76.2% +/- 1.4 to 88.0% +/- 2.0. Similarly, addition of washed platelets without plasma also increased (p less than 0.05) neutrophil adherence from 67.9% +/- 5.8 (without added platelets) to 94.2% +/- 1.6 (with 300,000 platelets/mm3 added). In contrast, no augmentation of neutrophil adherence occurred if platelets had their aggregation response suppressed by pretreating platelet donors with aspirin. SEM supported these findings by showing platelets in close association with neutrophils adhering to nylon fiber. These findings emphasize the importance of platelet numbers and reactivity on the adherence of neutrophils.