Relative binding affinity IgG Species Polyclonal Rabbit ++++ +++ Human IgG ++++ ++++ Dog +++ IgM —- + IgD —- + IgA —- + Cow ++ ++++ Horse ++ ++++ Goat - ++ Guinea pig ++++ ++ Sheep +/- ++ Pig +++ +++ Rat +/- ++ Mouse ++ ++ Chicken —- +	Species/ Subclass Protein-A Protein-G Monoclonal Human Mouse Rat IgG 1 ++++ ++++ IgG 1 + ++++ IgG 1 —- + IgG 2 ++++ ++++ IgG 2a ++++ ++++ IgG 2a —- ++++ IgG 3 —- ++++ IgG 2b +++ +++ IgG 2b —- ++ IgG 4 ++++ ++++ IgG 3 ++ +++ IgG 2c + ++ —- (weak or no binding) ++++ (Strong binding)
Table 1: Relative Affinity of Immobilized Protein-A and Protein-G for Various Antibody Species and Subclasses of Polyclonal and Monoclonal IgG.