Secretory and serum antibodies against Streptococcus lactis, Streptococcus thermophilus, and Lactobacillus bulgaricus in relation to ingestion of fermented milk products

Abstract

Serum, saliva, and urine were analyzed for the presence of IgA, IgG, and IgM antibodies reactive with the yoghurt bacteria Streptococcus thermophilus and Lactobacillus bulgaricus. A comparison was made between four subjects who frequently ate yoghurt and four subjects who never ate yoghurt. Salivary IgA and serum IgG activity against the milk-fermenting bacterium S. lactis was studied in five other subjects before, during, and after a period of ingestion of a fermented milk product, filmjölk. All analyses were carried out by an enzyme-linked immunosorbent assay method. Antibody activity against the yoghurt bacteria was found in saliva, serum, and urine. No difference in antibody activity between yoghurt eaters and non-yoghurt eaters was measured for salivary IgA, but for serum IgG a lower activity against S. thermophilus was present among the yoghurt eaters. Antibody activity against S. lactis was present already before the ingestion of filmjölk began, and the activity was not altered during the period of ingestion. It is concluded that in adult subjects, the ingestion of milk-fermenting bacteria does not result in a significant change in the antibody activity against these bacteria.