Production of interferon induced by Streptococcus thermophilus: Role of CD4(+) and CD8(+) lymphocytes

The effects of non-pathogenic bacteria on the production of cytokines by circulating mononuclear cells from healthy subjects were studied both in vivo and in vitro. Feeding a diet containing fermented daily products, induced a significant increase of 2-5A synthetase activity in these cells suggesting a production of interferons. An in vitro study showed that mononuclear cells produced interferon-gamma in presence of lactic bacteria like Lactobacillus acidophilus, Streptococcus lactis, and Streptococcus thermophilus. S. thermophilus induced also the production of interleukin-1 beta. All the studied bacteria, including Bifidobacterium and Lactobacillus casei induced the production of interleukin-6. In the presence of S. thermophilus, 76% and 62% reduction of interferon-gamma was observed when anti-CD4 co-receptor and anti-CD8 co-receptor antibodies were added in the medium, respectively. Thus, the recognition of a. thermophilus involved the two pathways of major histocompatibility complex, and muramyl dipeptide a component of bacterial wall could explain the part recognized by CD4+ lymphocytes. (C) Elsevier Science Inc. 1997.