Immunological effects of probiotic strain Enterococcus faecium EF1 was evaluated through the production of cytokines, superoxide anion (O2.-) and prostaglandin E2 (PGE2) in murine macrophage cell line RAW 264.7. In addition, the responses were contrasted with a pathogenic coliform, Escherichia coli strain K88. After 12-h co-incubation of RAW 264.7 with E. faecium EF1 or E. coli K88, the culture supernatants were collected for further analysis of cytokines (TNF-α, IFN-γ, IL-1β, IL-6, IL-12, IL-8 and IL-10) and inflammatory mediators including superoxide anion (O2.-) and PGE2. The results showed that, E. faecium EF1 induced an increased (P