Mucosal immune response induced by an exopolysaccharide produced by a strain of Lactobacillus.

VINDEROLA, C.G.; PERDIGÓN, G.; DUARTE, J.; FARNWORTH, E.; MATAR, C.

Córdoba (Argentina)

Congreso; VII Congreso Latinoamericano de Inmunologia.; 2005

The effect of exopolysaccharides produced by lactic acid bacteria on the mucosal immune system is not completely understood yet. Aim: to study the mucosal immune response of the oral administration of a purified exopolysaccharide (kefiran), present in kefir. BALB/c mice received an exopolysaccharide produced by a strain of Lactobacillus kefiranofaciens, for  2, 5 or 7 consecutive days. The number of IgA+, IgG+, IL-4+, IL-6+, IL-10+, IL-12+, IFNg+ and TNFa+ cells were determined on histological slices of small intestine (SI). Cytokines were also determined in serum and intestinal fluid. We observed a) an increase in the number of IgA+ cells in SI (105±4, 109±6, 106±5 cells/10 fields for 2, 5 or 7 days, respectively, control value 77±4), IgG+ cells were not modified; b) the number of IL-4+, IL-6+ and IL-10+ cells in SI were similar to control values (39±2, 53±2, 35±4, respectively); c) in serum, IFNg and IL-10 increased (92±12 and 164±3 pg/ml) for 7 days, respect to control (33±8 y 105±20); d) in intestinal fluid, IL-4 and IL-12 increased for 2 days (29±3 and 29±5 pg/ml) and for 5 days (26±7 and 34±4 pg/ml), respect to the control (11±1 and 20±2 pg/ml). Results show a T-independent response without modification of the intestinal homeostasis. The increase of IgA would be due to the clonal expansion of B IgA+ limphocytes of the SI lamina propria. The increase of cytokines would be due to their production by cells of the innate response: IL-4 by mastocites, IL-12 by dendritic cells, IFNg by macrophages and IL-10 by dendritic cells and macrophages. Kefiran modulates the intestinal immune response.