Induction of Protective IgA by Intestinal Dendritic Cells Carrying Commensal Bacteria
Sorry for the long title, but the basic idea is that normal flora interacts with the immune cells of the GI tract at a local level only. The presence of normal flora such as lactobacillus or acidopholus does not elicit a systemic immune response as would be expected by the presence of a pathogen such as salmonella, candida or clostridium. Do we need any more evidence than this that these bacteria are supposed to be there and that destroying them with antibiotics without thought to replacing them is poor medicine?
Science — Abstracts: Macpherson and Uhr 303 (5664): 1662