Figure 2. Effect of histamine and JNJ 28610244 on lactoferrin release.

Human PMNs (1×10⁶) were pretreated for 5 min without (−) or with (+) the indicated concentrations of histamine (A) or the H₄ receptor agonist JNJ 28610244 (B). Thereafter, PMNs were incubated on plates coated with fibrinogen in the presence of fMLP (0.1 μM) to engage Mac-1. After 30 min, the concentration of lactoferrin in the extracellular milieu was measured by ELISA, as described in Materials and Methods. The data are expressed as fold increase over controls (cells incubated for 30 min on plates coated with fibrinogen in the absence of fMLP) and are the mean ± sem of four to eight (A) or six to eight (B) separate experiments. Measurements for each experimental condition were performed in triplicate. *P < 0.05, and ***P < 0.001; ns, not significant by one-way ANOVA with post hoc Bonferroni's test compared with fMLP-stimulated adherent cells.