Abstract:

Phycobiliprotein is a light-harvesting pigment in red and blue-green algae. It is widely used in the pharmaceutical
industry due to its antioxidant activity and anticancer activity. In Nostoc sphaeroides Kützing, phycocyanin and
phycoerythrin are major varieties of phycobiliprotein. However, the effect of Nostoc sphaeroides Küting phycobiliprotein
(NSKP) on immune functions remains unclear. In the present study, the immunoenhancing effect of NSKP in Kunming
mice was explored. The mice were administered with NSKP at dosages of 100, 300 and 500 mg/(kg·d) (body mass) by
gavage once a day. After administration for 30 consecutive days, the immune parameters including the phagocytosis of
peritoneal macrophages, natural killer cell activity, the proliferation of T lymphocytes, cytokines levels, antibody production,
hemolytic complement activity and delayed-type hypersensitivity were measured. The results showed that NSKP promoted
the phagocytosis of peritoneal macrophages, the function of natural killer cells, and the proliferation of T lymphocytes, as
well as increased the levels of interleukin (IL)-2 and IL-4 and serum hemolysin. Meanwhile, the response of delayed-type
hypersensitivity in NSKP group was also dramatically higher than that in the control group. Therefore, NSKP is a potential
immunoenhancing agent.

Key words: Nostoc sphaeroides Küting, phycobiliprotein, immune function, cytokine