RESPONSE OF HEIFER MAMMARY-GLAND MACROPHAGES AND NEUTROPHILS TO INTERFERON-GAMMA STIMULATION IN-VITRO

The phagocytic and killing abilities of heifer mammary gland macrophag es (MO) and neutrophils were evaluated after exposure to recombinant b ovine interferon-gamma (rBoIFN-gamma) stimulation in vitro. Macrophage s or neutrophils were cultured for 2 h with 0, 10(2), 10(4) and 10(5) units rBoIFN-gamma/mL. Phagocytosis assays were performed by incubatio n with Staphylococcus aureus at a leukocyte: bacteria ratio of 1:10. A fter 45 min, cells were stained with acridine-orange and phagocytic an d killing abilities were determined. Although rBoIFN-gamma had no effe ct on MO phagocytic activity, neutrophil phagocytic activity after inc ubation in 10(4) units rBoIFN-gamma (41.62%) was significantly higher than 0 (25.24%) or 10(2) units rBoIFN-gamma (24.73%). Neutrophil and M O killing abilities were not affected by any dose of rBoIFN-gamma. Res ults suggested that rBoIFN-gamma promoted neutrophil phagocytic activi ty, but did not affect neutrophil killing or overall MO function in vi tro.