Differential pattern of human blood neutrophil activation after stimulation with organic dust in vitro and in vivo.

Objective: To study activation of blood neutrophils in subjects after in vitro and in vivo stimulation.

Methods: Blood from healthy volunteers was collected before and after their exposure to organic dust in a pig farm. Surface markers of neutrophil activation were analyzed by flow cytometry.

Results: In vivo, there was a diurnal variation in basal levels of CD11b. Swine dust exposure increased the number of blood neutrophils and the levels of myeloperoxidase without effects on CD11b or Cys-X-Cys receptor 1 (CXCR-1) expression. However, a positive correlation between changes of myeloperoxidase and CD11b expression was observed. In vitro, N-formyl-methionyl-leucyl-phenylalanine (fMLP), lipopolysaccharide (LPS), leukotriene (LT)B4, LTD4, and swine dust stimulated the expression of CD11b. fMLP, LPS, and LTB4 diminished the expression of CXCR-1.

Conclusions: Exposure to swine dust in vitro activated neutrophils and inhalation of swine dust caused neutrophilia.