Binding of purified recombinant PIII protein to epithelial cells. A. Ectocervical cells were incubated for 1 h at 37°C with increasing concentrations of the purified PIII protein (range 2 nM-4.2 μM). The binding was analysed by FACS using mouse anti-PIII antibodies and an R-Phycoerythrin-conjugated secondary antibody. The values are reported as net mean fluorescence intensity (MFI). B. Saturation curve of PIII binding to ectocervical cells. Analysis was performed on data reported in A. The Kd value was calculated as the PIII concentration that determines the saturation of 50% of the receptors present on the cells. C. Representative flow cytometry profiles of the binding of 1 μM PIII to ectocervical, endocervical and urethral cells. Grey line profiles represent the cells incubated with the primary and secondary antibodies in absence of the PIII protein.