Characterization of monoclonal antibodies physically adsorbed onto polystyrene latex particles

The physicochemical and immunochemical properties of monoclonal antibodies (MAbs), adsorbed onto polystyrene latex particles, have been investigated. Both native and pH 2 pretreated MAbs were compared before and after immobilization. It was found that the antigen binding capacity of the immobilized, acidic pretreated MAbs was significantly higher than for the immobilized, native IgG molecules. This enhanced antigen binding capacity appeared to be due to an improved molecular orientation following adsorption of the monomeric, pH 2 treated IgG fraction. Additionally, experiments using F(ab′) 2 fragments demonstrated that the Fc portion of the MAb molecule is of major importance for achieving the enhanced binding capacity. Binding studies showed that the (apparent) affinity of native and pH 2 pretreated MAbs were similar; the K a values of the immobilized MAbs were higher than those of MAbs in solution.