The efficacy of a commercial beta-glucan preparation, EcoActiva, on stimulating respiratory burst activity of head-kidney macrophages from pink snapper (Pagrus auratus), Sparidae.

This study investigated the in vitro effects of a commercial beta-glucan preparation, EcoActiva, on the respiratory burst activity of head-kidney macrophages isolated from pink snapper (Pagrus auratus), a marine fish cultured in Australia. Macrophages incubated with EcoActiva displayed morphological characteristics of activation, and were stimulated to produce superoxide. Pre-incubation with low levels of EcoActiva significantly increased the response to phorbol myristate acetate (PMA) and lipopolysaccharide (LPS), indicating that EcoActiva could prime these macrophages. Co-culturing macrophages with both LPS and PMA, or EcoActiva and PMA, increased burst activity compared with the response to PMA alone, however, this increase was additive and not synergistic. These results suggest that EcoActiva is able to stimulate non-specific immunity in snapper through increased respiratory burst activity of macrophages, an important component of the host defence network.