[Adherence of E. coli strains with various adhesins to macrophages from bone marrow and the cell line P 388D1].

Abstract

The adherence of E. coli with different hemagglutination patterns to mouse-bone-marrow-derived macrophages and macrophages of the cell line P 388D1 was investigated. The bacterial strains used showed different adherence to macrophages or red blood cells. MS-adhesins identified by hemagglutination tests were also involved in the attachment of bacteria to macrophages. In addition, strains containing both, MS and MR adhesins, simultaneously showed a participation of their MR-adhesins in adherence to macrophages. This could be shown by inhibition experiments with alpha-D-mannose. Bacteria of strain D 133 failed to induce hemagglutination of any source of erythrocytes tested, though MR-adherence to macrophages could be found. In contrast, other strains known to carry MR-hemagglutinins on their cell surface, did not attach to macrophages, even if much higher numbers of bacteria were used. A linear correlation between the amount of bacteria used and the number of adherent bacteria/macrophage was detectable. The number of bacteria found on the macrophages differed according to the population of macrophages studied, indicating differences in the expression of corresponding receptors in the macrophage plasma membrane. In order to investigate the role of fimbriae in adherence, bacteria were used which had been grown under fimbriae suppressing conditions. Some of the bacterial strains showed a 10 to 30 fold reduction in adherence to macrophages upon this treatment, indicating the importance of fimbriae-associated adhesins in the interaction of bacteria and phagocytes. On the other hand, three bacterial strains could be identified, whose adherences was not influenced by such culture conditions. This means that beside fimbrial adhesins even membrane bound adhesins could be involved in the phagocytic process.