RESUMO
OBJECTIVE: We investigated whether oral administration of skimmed and concentrated bovine late colostrum (SCBLC) activates the immune system and protects against influenza virus (Flu) infection. METHODS: Murine Peyer's patch (PP) cells (2.5 105) were cultured in 0.1 ml RPMI-1640 supplemented with SCBLC at a concentration of 0, 0.1 or 1.0 mg/ml. To determine the levels of IL-12 and IFN-, supernatants were collected on day 3. Mice were orally administered sterile saline solution (control group), or 400 g/g body weight (SCBLC 400 group) or 2,000 g/g body weight (SCBLC 2,000 group) of SCBLC for three weeks. These mice were measured for natural killer (NK) cells activity on PP cells, splenocytes and lung cells. Also, these mice in the control and SCBLC 2,000 groups were infected with Flu and were measured for the accumulated symptom rate. RESULTS: In PP cells cultured with SCBLC, the levels of IL-12 and IFN- were significantly increased in vitro. Oral administration of SCBLC to mice significantly increased NK cell activity of PP cells, splenocytes and lung cells. The accumulated symptom rate of the SCBLC 2,000 group was significantly lower than that of the control group in a mouse model of Flu infection. CONCLUSION: These results indicate that oral administration of SCBLC activates not only systemic cellular immunity but also local cellular immunity, such as in the respiratory tract, and that activation of cellular immunity is one of the mechanisms of amelioration of Flu infection.
