Immunostimulating activity of cell walls from lactic acid bacteria and related species

In the present study the immunostimulating capacity of cell walls of lactic acid bacteria, present in a fermented milk (BIO MILK) with proven biotherapeutic activity, was analyzed. Cell walls and peptidoglycans were isolated, resuspended in water and thereafter administered orally (50 mu g/day) to mice for different periods (2, 5 and 7 days). After these periods mice were sacrificed and phagocytic activity of the peritoneal macrophages and immunoglobulin A (IgA) levels in intestinal fluid were analysed. It was observed that Lactobacillus casei was able to stimulate phagocytosis both by the cell wall and the peptidoglycan, whereas it did not produce changes in IgA. L. acidophilus, on the other hand, produced an increase in the levels of IgA without modifying phagocytosis. Propionibacterium acidipropionici only showed immunostimulating activity with the cell wall, but not with the peptidoglycan. These results do not show any relationship with previously studied chemical composition of the cell walls. However, a relationship was found with the presence of molecules emerging from the surface (observed with electron microscopy).