Immunostimulant effects of dietary Spirulina platensis on carp, Cyprinus carpio

Immunostimulant effects of the dietary Spirulina (Spirulina plantensis) were studied in carp, Cyprinus carpio. For this purpose, fish were fed with Spirulina and the parameters of non-specific defence mechanisms, including phagocytosis and production of superoxide anion were performed at 1, 3 and 5 days after Spirulina administration. The results showed that Spirulina enhanced responses of phagocytic activity and superoxide anion production in kidney phagocytic cells. This activation of kidney cells was observed for at least 5 days post treatment. The expression of interleukin (IL)-1β and tumor necrosis factor (TNF)-α genes also increased in fish treated with spirulina. On the other hand, the expression of IL-10 gene was decreased. Furthermore, the numbers of Aeromonas hydrophila were decreased in the liver and kidney of spirulina-treated fish. These findings suggest that dietary Spirulina has immunostimulatory effects on the innate immune system of carp.