TNF-α is associated with the neutrophil plasma membranes and stimulates IL-12 expression in DCs. (A) Histogram of surface TNF-α expression on POD 1 airway neutrophils from unstimulated (thick gray line) or cytochalasin B–stimulated (thick black line) control Ig–treated Ext CI Balb/c → B6 lung recipients or (thin black line) G-CSF Ab–treated Ext CI Balb/c → B6 lung recipients or (shaded) Ext CI Balb/c → B6 TNF-α^−/− lung recipients. Results are representative of 2 independent experiments. (B) BMDC culture (DCs only) or BMDCs cocultured with unstimulated (control Ig) or cytochalasin B–stimulated (cytochalasin B) POD 1 Ext CI Balb/c → B6 lung recipient airway neutrophil plasma membranes in the absence or presence of TNF-α Ab (TNF-α Ab or cytochalasin B + TNF-α Ab, respectively) or with POD 1 G-CSF Ab–treated Ext CI Balb/c → B6 lung recipient airway neutrophil plasma membranes (G-CSF Ab). One day later, IL-12 accumulation was assessed in culture supernatants. Results are representative of 2 independent experiments. Data represent the means ± SEM. *P < .05; **P < .01.