DETECTION OF INTESTINAL FLORA-DERIVED BACTERIAL-ANTIGEN COMPLEXES IN SPLENIC MACROPHAGES OF RATS

We studied the presence of bacterial antigens in rat tissues. We produ ced a monoclonal antibody (MAb 2E9) directed against intestinal flora- derived peptidoglycan-polysaccharide complexes from human and rat fece s. With several immunological techniques, the specificity of 2E9 for t his bacterial product was demonstrated. Using 2E9 in an immunohistolog ical assay, we were able to show the presence of bacterial products in macrophages in the red pulp of spleens of conventional Lewis rats. Ho wever, we found no correlation between the development of the intestin al nora and positive spleen staining with MAb 2E9. The results were co nfirmed by immunohistology with a previously described MAb 2-4 directe d to muramyl dipeptide. Other lymphoid organs did not stain positively with 2E9 and 2-4. Neonatal and young rats showed no staining of the s pleen, but positivity could be induced by injecting peptidoglycan-poly saccharide complexes systemically. We conclude that bacterial fragment s are present in splenic macrophages of conventional rats.