Thirty-two Helicobacter pylori strains were screened for haemagglutination (HA) activity with erythrocytes of 11 different animal species. Twenty-three strains (72%) that agglutinated human erythrocytes exhibited a broad-spectrum HA profile. Human, guinea pig and bovine erythrocytes high in sialoglyco-conjugates were strongly agglutinated by most strains. Except for two, seven strains (22%) that did not agglutinate human erythrocytes exhibited a narrow-spectrum HA profile, commonly not inhibitable by sialoglycoconjugates or N-acetylneuraminlactose (NANLac). Strains were classified into three major HA classes. HA of 10 strains (31%) in class I was inhibited by different combinations of NANLac, orosomucoid or fetuin, but not by asialofetuin, suggesting the presence of sialic acid-specific HAs probably recognizing NeuAc alpha-(2-3)- Gal isomer. Twelve strains (38%) in class II exhibited a different receptor specificity binding to different combinations of NANLac, orosomucoid and fetuin, as well as asialofetuin. No inhibition was observed with 10 strains (31%) in class III; thus, this receptor seems different from both the other classes. Of 21 strains (66%) in classes I and II, HA of 11 strains (34%) was inhibited with NANLac, 14 strains (44%) with orosomucoid and 15 strains (47%) with fetuin. The great heterogeneity observed in HA patterns indicates that the HAs of different strains may recognize a heterogeneous class of sialoglycoconjugates on the erythrocyte membrane.
