Eukaryotic cell uptake of heparin-coated microspheres: a model of host cell invasion by Chlamydia trachomatis

Using polystyrene microspheres coated with heparin or heparan sulfate, it w as shown that coated microspheres specifically bound eukaryotic cells and w ere endocytosed by nonprofessional phagocytic cells. Coated microspheres di splayed properties of binding to eukaryotic cells that were similar to thos e of chlamydiae, and the microspheres were competitively inhibited by chlam ydial organisms, Endocytosis of heparin-coded beads resulted in the tyrosin e phosphorylation of a similar set of host proteins as did endocytosis of c hlamydiae; however, unlike viable chlamydial organisms, which prevent phago lysosomal fusion, endocytosed beads were trafficked to a lysosomal compartm ent, These findings suggest that heparin-coated beads and Chlamydia trachom atis enter eukaryotic cells by similar pathways.