Enhancement of chicken macrophage phagocytic function and nitrite production by dietary Spirulina platensis

The effects of dietary Spirulina platensis on chicken macrophage phagocytic function and nitrite production were examined. Day old broiler (meat-type) chicks were randomly assigned to various pens of electrically heated wire batteries. Dietary treatment groups included a basal diet with no dietary Spirulina added, and three additional groups with 0.5, 1.0 acid 2.0% dietary Spirulina. Feed and water were provided for nd libitum consumption from one day of age. Sephadex (R) -elicited macrophages were harvested at 14. 35 and 42 days of age. Phagocytosis assay was performed by Lo-incubating sheep red blood cells (SRBC) with the adherent macrophage monolayers. For nitrite quantification, macrophage cultures from various dietary treatment groups were stimulated in the presence or absence of 1 mug/mL of Escherichia coli lipopolysaccharide. These culture supernatant fractions were then tested fur nitrite levels using the Greiss reagent technique. All Spirulina dietary group macrophages exhibited an enhanced phagocytic activity in terms of overall phagocytic percentage (range = 28 to 39% versus 24 to 25% in the basal group) and the average number of SRBC per phagocytic macrophage (range = 2.2 to 3.6 versus 1.8 to 2.5 in the basal group). This increase was linear with each incremental increase of dietary Spirulina. While LPS-induced nitrite: levels in macrophages from basal diet group ranged from 60 to 278 muM over the three developmental ages, these levels in all Spirulina dietary groups were significantly higher (0.5% group range = 198 to 457 muM; 1.0% group range = 161 to 359 muM and 2.0% group range = 204 to 470 muM. These data clearly show that Spirulina platensis feeding upregulates macrophage phagocytic as well as metabolic pathways leading to increased nitric oxide synthase activity. These findings therefore imply that Spirulina platensis may enhance the functions of mononuclear phagocytic system thereby increasing the disease resistance potential in chickens.