Neutrophils in suspension or adherent to ICAM-1 and ICAM-2 release TNF in response to chemoattractants. Purified neutrophils in suspension or after adhesion to ICAM-1– or ICAM-2–coated plates were stimulated with LTB₄ for 15 (n = 5, 7, and 7 samples, respectively) or 30 min (n = 4, 6, and 6 samples, respectively; A) or KC and C5a (n = 3) for 30 min (B). Control samples (in suspension or adherent to ICAM-1 o ICAM-2) were treated with PBS (n = 6, 7, and 7, respectively). Supernatants were assayed for TNF by ELISA. Graphs show means ± SEM of 3 independent experiments. ND, not detected. Significant differences from PBS control are indicated by asterisks. *, P < 0.05; **, P < 0.01; ***, P < 0.001.