BLOOD-GROUP PHENOTYPE DETERMINES LECTIN-MEDIATED ADHESION OF PSEUDOMONAS-AERUGINOSA TO HUMAN OUTER EAR CANAL EPITHELIUM

Pseudomonas aeruginosa is the most frequent bacterial pathogen causing acute diffuse otitis externa. In a recent prospective phase II study we demonstrated that lectin-mediated bacterial adhesion can be blocked by receptor-analogue carbohydrates in patients suffering from Pseudom onas aeruginosa-induced acute otitis externa. In this investigation, h uman ABO blood group antigens were analysed on outer ear canal epithel ial cells with standard routine histological procedures by monoclonal antibodies for the blood groups A and B, and with Ulex europaeus I lec tin for the blood group 0, respectively. In all cases (n = 20) the blo od groups could be shown immunohistologically. P. aeruginosa-specific adhesion and inhibition assays were performed in the presence of N-ace tylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), D-mannose and A-like substance. Outer ear canal tissue sections were incubated with P. aeruginosa (strain PA 60), presenting lectin-specificity for GalNA c. Sections from patients presenting with blood group A were closely s ettled with bacteria in the presence of non-specific GlcNAc, D-mannose and PBS however, GalNAc and A-like substance inhibited the microbial adhesion. Amongst others, P. aeruginosa present adhesion molecules (le ctins) with specificity for GalNAc. Thus, the correlation between bloo d group A phenotype and P. aeruginosa-induced acute diffuse otitis ext erna was investigated. Statistical evaluation proved a highly signific ant association. These data support the hypothesis that P. aeruginosa lectins with GalNAc specificity apparently adhere to GalNAc moieties, representing the terminal blood group A-determinant and further indica te that patients presenting with blood group A may have a genetic disp osition for this form of otitis externa.