The use of fibronectin-coated polyvinyl chloride microtest plates to detect monoclonal antibody-binding to adherent tumor cells

This report describes the use of fibronectin-coated polyvinyl chloride (PVC) plates as a time-saving modification in an assay measuring antibody-binding to live adherent tumor cells. Three cell lines (A-431, Colo 16 and UCLA-SO-P3) derived from human squamous cell carcinomas (SCC) and forming monolayers in cultures were plated onto flexible PVC microtest plates rather than the commonly used rigid polystyrene plates. In PVC plates, two of the three cell lines (A-431 and Colo 16) grew as foci of clumped cells instead of monolayers. Coating of the plates with plasma fibronectin restored the monolayer morphology. [ 125I] Staphylococcal protein A radioimmunoassays measuring the binding of a monoclonal anti-β 2 microglobulin antibody to the cells were slightly, but consistently, more sensitive in coated PVC plates than in polystyrene plates. In contrast, the sensitivity of the radioimmunoassay was remarkably constant when the assay was performed on the third cell line (UCLA-SO-P3), which formed monolayers in any of the conditions tested. Preliminary experiments suggested that the inability to form monolayers on uncoated PVC plates correlates with the amount of fibronectin associated with the cell surface.