An endogenous heparin-binding lectin activity isolated from rat lung was separated into two distinct isolectin forms which showed subtle changes in carbohydrate specificity. The two lectin forms displayed different specificities toward alginic acid-purified cystic fibrosis isolates of Pseudomonas aeruginosa when assayed by inhibition of both hemagglutination and [3H]heparin binding. This ability of isolectin forms to show higher affinity toward alginic acid from certain P. aeruginosa strains may suggest that there is a selective mechanism in the colonization of patients with cystic fibrosis.
