Model of Removal of Immunoglobulins from Plasma by Extracorporeal Immunoadsorption with Sepharose-Protein A

A mathematical model is developed which relates the time needed to perform immunoadsorption with Sepharose-Protein A to the column dimensions and choice of whether to use one or two columns. Measurements of parameters needed to apply the model, including the reaction rate constant and adsorption capacity, are reported. It is concluded that one large column can remove immunoglobulins more quickly than two smaller columns containing the same total volume of Sepharose-Protein A, but with the penalty of a greater loss of other plasma constituents. The model involves only simple computations, and can be applied to other immunoadsorbents if the dissociation constant of the complex formed by adsorption is lower than the final plasma concentration of the molecule adsorbed.