Effect of Pseudomonas aeruginosa lectins on phagocytosis of Escherichia coli strains by human polymorphonuclear leucocytes

The D-galactosephilic lectin of Pseudomonas aeruginosa (PA-I) agglutinates cells of E. coli O₈₆B₇, while its other lectin (PA-II) agglutinates E. coli O₁₂₈B₁₂ cells. Both lectins react with human peripheral leucocytes. Exposure of the human leucocytes to either of the two Pseudomonas lectins was found to depress their phagocytic activity towards E. coli O₈₆B₇ and O₁₂₈B₁₂ strains, as well as towards E. coli B cells, which are not agglutinated by the lectins. However, coating the E. coli O₈₆B₁₂ and O₁₂₈B₁₂ cells, respectively, with PA-I and PA-II lectins increased their phagocytosis by untreated human leucocytes. Control experiments in which E. coli O₈₆B₇ and O₁₂₈B₁₂ cells were exposed to PA-II and PA-I, respectively, did not lead to any increase in their phagocytosis.