形態・生理1

[IV-16-17] Suppression of neutrophil phagocytosis in mastitic milk

*平野 雅人¹、久枝 啓一²、津上 優作¹、新居 隆浩¹、鈴木 直樹¹、磯部 直樹¹ (1. 広大院統合生命、2. 岡山理科大獣医)

[Objective] After collecting mastitic milk, the viable bacterial count decreases dramatically during its preservation by the neutrophil phagocytosis. The aim of the present study was to investigate whether neutrophil phagocytosis can be suppressed by colchicine. [Method] Milk was collected 24 h after lipopolysaccharide was intramammary infused in Tokara and Shiba goat, and centrifuged to separate neutrophils. Then 0, 0.1 and 1 mg/mL of colchicine and 2.0×10⁷cell/mL of inactivated Escherichia coli (EC) or Staphylococcus aureus (SA) were added into neutrophils and the mixture was incubated at 37 ℃ for 30 min. The mixture was smeared on a slide glass, followed by Giemsa staining. [Result] Percentage of neutrophils that phagocytosed EC or SA were significantly lower in both the colchicine 0.1 and 1 mg/mL groups than in control group. The number of bacteria in a neutrophil was also significantly lower in both colchicine groups. These results suggest that the colchicine can inhibit the neutrophil phagocytosis, which enables bacterial examination from mastitic milk.