Induction of IFN-gamma and IL-1 alpha production in macrophages stimulated with phosphopolysaccharide produced by Lactococcus lactis ssp. cremoris

The induction of interferon (IFN) and interleukin-1 (IL-1) production in murine macrophages by a phosphopolysaccharide, produced by a dairy lactic acid bacteria, Lactococcus lactis ssp. cremoris, was investigated. When the phosphopolysaccharide was added into macrophage cultures at concentrations from 1 to 200 micrograms/ml, substantial IFN titers (6.2-79.2 IU/ml) were detected. Using the reverse transcription-polymerase chain reaction (RT-PCR), the expression of mRNA encoding IFN-gamma was verified in spleen macrophage cultures. Macrophages stimulated with the phosphopolysaccharide also produced IL-1 alpha at a concentration of 50 micrograms/ml. This study showed for the first time that phosphopolysaccharide derived from a dairy lactic acid bacterium can induce IFN-gamma and IL-1 alpha production in macrophages. These findings strongly suggest that the phosphopolysaccharide is a type of 'biological response modifier' and the fermented dairy foods containing Lactococcus lactis ssp. cremoris can be designated as a physiologically functional food.