Neutrophil adhesion and distribution to a pure fibrin-coated surface was measured under flow conditions or under static conditions. Fibrin was formed on a gelatin-coated glass coverslip by incubation in a fibrinogen solution (5 mg/mL in HEPES buffer) for 30 minutes at room temperature. Subsequently, incubation with thrombin (1 U/mL HEPES buffer for 10 minutes at 37°C) resulted in the formation of pure fibrin. For adhesion under flow conditions, PMNs (2 × 10⁶ cells/mL HEPES buffer) were perfused at shear stresses of 80 mPa (5 minutes at 37°C). Adhesion to fibrin under static conditions was measured after a PMN incubation for 45 minutes at 37°C (2 × 10⁶ cells/mL HEPES buffer). For blocking studies, PMNs were incubated with antibodies against FcγRIII (CLB FcR gran/1, CD16), β2-subunit (IB4, CD18), MAC-1 (44a, CD11b), or L-selectin (LAM1-3, CD62I) for 30 minutes at room temperature. The fibrin-coated coverslip or the PMNs were incubated with neuraminidase (0.25 U/mL) for 20 minutes at 37°C. Data represent the number of adhering neutrophils per square millimeter or the cluster index as a percentage of control. The absolute control values are given in parentheses (mean ± SE, n = 4 to 6).

Abbreviations: NA, neuraminidase; ND, not determined.

Statistically significant effect of treatment was determined by paired Student's t-test (P < .05).