Effect of mucin on Campylobacter jejuni association and invasion on HEp-2 cells.

We report the development of an in vitro assay using HEp-2 cell monolayers in which cell association of five C. jejuni strains and E. coli K12 C600 were tested under different experimental conditions. Both total cell associated colony forming units (CFU) and the CFU protected from gentamicin killing (i.e. internalized bacteria) were determined. Pretreatment of HEp-2 cells with mucin (100 micrograms/ml) enhanced internalization of four fresh isolates of C. jejuni by 3.2 to 20.7-fold, depending on the strain, but not internalization of C. jejuni K105 (a stock culture) or E. coli C600. Mucin also increased the total number of cell associated C. jejuni fresh isolates by 2 to 3.4-fold, the four strains yielding similar results. We conclude from these studies that mucin, which has been shown to be a prerequisite of intestinal colonization by C. jejuni, also promotes infectivity.