Lack of adherence of clinical isolates of Pseudomonas aeruginosa to Asialo-GM(1) on epithelial cells

Numerous studies have reported that asialo-GM(1), gangliotetraosylceramide, or moieties serve as epithelial cell receptors for Pseudomonas aeruginosa. Usually this interaction is confirmed with antibodies to asialo-GM(1) Howe ver, few, if any, of these reports have evaluated the binding of fresh clin ical isolates of P. aeruginosa to asialo-CM1 or the specificity of the anti bodies for the asialo-GM(1) antigen. We confirmed that asialo-GM(1) dissolv ed in dimethyl sulfoxide could be added to the apical membrane of Madin-Dar by canine kidney cells growing as a polarized epithelium on Transwell membr anes (J. C Comolli, L. L. Waite, K. E. Mostov, and J. N. Engel, Infect. Imm un. 67:3207-3214, 1999) and that such treatment enhanced the binding of P. aeruginosa strain PA103. However, no other P. aeruginosa strain, including eight different clinical isolates, exhibited enhanced binding to asialo-GM( 1)-treated cells. Studies with commercially available antibodies to asialo- GM(1) showed that these preparations had high titers of antibody to P. aeru ginosa antigens, including whole cells, purified lipopolysaccharide (LPS), and pill. Inhibition studies showed that adsorption of an antiserum to asia lo-GM(1) with P. aeruginosa tells could remove the reactivity of antibodies to asialo-GM(1) and adsorption of this serum with asialo-GM(1) removed ant ibody binding to P, aeruginosa LPS. Antibodies in sera raised to asialo-GM( 1) were observed to bind to P. aeruginosa cells by immunoelectron microscop y. Antibodies to asialo-GM(1) inhibited formation of a biofilm by P. aerugi nosa in the absence of mammalian cells, indicating a direct inhibition of b acterial cell-cell interactions. These findings demonstrate that asialo-GM( 1) is not a major cellular receptor for clinical isolates of P. aeruginosa and that commercially available antibodies raised to this antigen contain h igh titers of antibody to multiple P. aeruginosa antigens, which do not int erfere with the binding of P. aeruginosa to mammalian cells but possibly in terfere with the binding of P. aeruginosa cells to each other.