Analysis by flow cytometry of surface-exposed epitopes of outer membrane protein F of Pseudomonas aeruginosa

Antisera were produced in mice immunized with 18 synthetic peptide conjugates representing various regions throughout the length of the outer membrane protein F molecule of Pseudomonas aeruginosa and analysed by flow cytometry to identify those antisera capable of binding to the surface of whole cells of P. aeruginosa. Antibodies to peptides 9, 18, 10, and 4 were significantly cell-surface reactive. The maximum median percentage of antibody-binding cells in this assay was 36.6%. Over six different determinations, peptide 9 antisera binding to the cells ranged from 16.9 to 57.0% of the cell population. We propose that the surface accessibility of protein F epitopes varies during the cell cycle.