INCREASED ANTIBODY-PRODUCTION AGAINST GUT-COLONIZING ESCHERICHIA-COLIIN THE PRESENCE OF THE ANAEROBIC BACTERIUM PEPTOSTREPTOCOCCUS

Germ-free rats were colonized with E. coil alone, or with E. coli plus Lactobacillus acidophilus and a strain of the obligate anaerobic Gram -positive species, Peptostreptococcus. The presence of Peptostreptococ cus reduced translocation of E. coli, but increased the serum antibody response to E. coil antigen. Whereas the immunoglobulin G (IgG) anti- E. coil antibodies largely represented cross-reactive antibodies, thos e of the immunoglobulin M (IgM) isotype represented true anti-E. coli antibodies because they could not be absorbed by L. acidophilus or Pep tostreptococcus but could with E. coli. We suggest that peptostreptoco cci prime the gut immune system to other bacterial antigens and that t his could be a mechanism behind the reduced translocation of facultati ve anaerobes in the presence of obligate anaerobes.