Soluble and cell-associated haemagglutinins of Helicobacter (Campylobacter) pylori.

Some plate-grown strains of Helicobacter (Campylobacter) pylori that were harvested into phosphate-buffered saline and left for 1 h released soluble haemagglutinins. These caused high-titre agglutination of human and guinea-pig erythrocytes, whereas chicken, sheep and bovine erythrocytes were agglutinated at various titres. Six of 10 strains which had been subcultured repeatedly did not possess soluble haemagglutinins. Slide agglutination of bacterial suspensions demarcated the strains into two groups; Group 1 gave strong agglutination with most types of erythrocyte, Group 2 did not. By microtitration assay, all Group-1 strains but only two Group-2 strains produced a soluble haemagglutinin. Cell-associated haemagglutinins were found by microtitration assay in all strains of H. pylori, but higher titres were found within Group-1 strains. The supernates of broth-grown, shaken cultures also showed the presence of soluble haemagglutinins, with higher titres for recently isolated strains. Pre-treatment of human erythrocytes with neuraminidase from Arthrobacter ureafaciens and Clostridium perfringens abolished haemagglutination by the soluble, but not by the cell-associated haemagglutinin. The soluble haemagglutinin was inhibited by sialoproteins containing predominantly the N-acetylneuraminyl (2-3) galactopyranosyl [NeuAc(2-3)Gal] structure, fetuin, glycophorin and bovine N-acetylneuraminyl-lactose (NeuAc-Lac). Transferrin and human NeuAc-Lac, which contain predominantly the N-acetylneuraminyl (2-6) galactopyranosyl [NeuAc(2-6)Gal] structure were not inhibitory. However, bovine submaxillary mucin (BSM) was strongly inhibitory; it contains several structures with sialic acid linked 2-6 to oligosaccharides. These results suggest that the soluble haemagglutinin recognises a NeuAc(2-3)Gal structure, but has high affinity for another, as yet undetermined, sialic acid-containing structure.