Sorption of the four subclasses of human immunoglobulin G (hIgG) to recombi
nant protein G immobilized to microporous membranes was examined to further
the understanding and characterization of this medically-important system.
Using batch incubation, sorption of the individual hIgG subclasses was mea
sured in competitive and noncompetitive experiments. Individually, all subc
lasses had very similar sorption rates and equilibrium capacities. In contr
ast, for mixtures of the subclasses, binding was distinctly different, with
strong competitive binding occurring: as the system approached equilibrium
, significantly more hIgG1 and hIgG3 bound to the membrane than did hIgG2 a
nd hIgG4. A kinetic and equilibrium model was able to successfully simulate
the binding of hIgG1, hIgG2, and hIgG4 but not hIgG3. The results are rele
vant to the healthcare and biotechnology industries: (1) the diagnosis and
treatment of autoimmune diseases, (2) mitigation of rejection in recipients
of organ transplants, and (3) production of monoclonal antibodies for use
as therapeutic biopharmaceuticals.