Entamoeba histolytica: monoclonal antibody against the beta1 integrin-like molecule (140 kDa) inhibits cell adhesion to extracellular matrix components

We describe a monoclonal antibody (3C10) against the beta1 integrin-like molecule which immunoprecipitates two polypeptides of 140 and 155 kDa from detergent-soluble extract of Entamoeba histolytica. The 140-kDa polypeptide has been described as a beta subunit of the amoebic fibronectin receptor as it is recognized by an anti-integrin beta1 (human) monoclonal antibody in immunoblot assay. The receptor molecules were localized with the 3C10 monoclonal antibody in intracellular and surface membranes of E. histolytica trophozoites by immunofluorescence and immunogold labeling methods. Significant inhibitions of cell adhesion on extracellular matrix proteins such as fibronectin (56%) (P < 0.001) and collagen (50%) (P < 0.001) and partial inhibition on laminin (23%) (P > 0.1) were achieved by the monoclonal antibody.