Role for arachidonic acid metabolism and protein synthesis in recombinant bovine interferon-gamma-induced activation of bovine neutrophils.

Bovine neutrophils were preincubated with recombinant bovine interferon-gamma (rboIFN-gamma), and the molecular events leading to enhanced antibody-dependent (ADCC) and antibody-independent (AINC) neutrophil-mediated cytotoxicity and reduced random migration under agarose were investigated. Addition of alpha-amanitin, puromycin, or cycloheximide (RNA and protein synthesis inhibitors) during preincubation and assaying prevented the rboIFN-gamma-induced AINC enhancement and migration inhibition, but did not influence the enhancement of ADCC. Treatment of neutrophils with rboIFN-gamma consistently increased the synthesis of a 60 and a 94-95 kilodalton protein and of leukotriene B4 and 5-HETE. Neutrophils isolated from dexamethasone-treated cattle showed similar protein synthetic activity after rboIFN-gamma treatment, but these cells failed to show enhanced AINC. Neutrophils from dexamethasone-treated cattle have been shown to have depressed arachidonic acid metabolism. Addition of lipoxygenase inhibitors (NDGA and BW755c) to neutrophils from nondexamethasone-treated cattle following preincubation with rboIFN-gamma (i.e., after protein synthesis had occurred) eliminated the enhancement of AINC. Thus it was concluded that the metabolic events required for neutrophil activation by rboIFN-gamma are different for the three functions measured. The enhanced AINC response required both arachidonic acid metabolism and protein synthesis, inhibition of random migration required only protein synthesis, and enhancement of ADCC required neither.