Density and localization of P-fimbriae-specific receptors on mammalian cells: fluorescence-activated cell analysis.

More than 95% of acute non-obstructive pyelonephritis cases in children are caused by P-fimbriated Escherichia coli. Uroepithelial cells from individuals prone to urinary tract infections bind such bacteria more avidly than do cells from healthy controls. A high density of receptors for P-fimbriae on cells of the urinary tract and kidney may thus be an important host factor in the acquisition of upper urinary tract infections. In this communication we are describing methods to determine the densities and localization of P-fimbriae receptors on mammalian cells. To determine the receptor density on cells in suspension, the cells were incubated with fluorescein-labelled P-fimbriated E. coli. They were then subjected to fluorescence-activated cell sorting (FACS) analysis which monitors both the size and the relative fluorescence of each cell. FACS analysis proved versatile for rapid and specific analyses of P-fimbriae receptor densities on large numbers of any chosen type of cell. The fluorescein-labelled P-fimbriated E. coli were also useful in localizing P-fimbriae receptors in tissues. These techniques are not limited to the assessment of P-fimbriae receptor densities and tissue localization but open up new aspects for studies of the specificities involved in the interactions between other microorganisms (e. g. parasites, bacteria and virus) and their host cells.