Preparation and some properties of dimeric rabbit IgG antibody.

By reacting rabbit IgG with the fragment AB of protein A from S. aureus (mol. wt 14,000) an IgG dimer was formed with an approx. mol. wt of 320,000 and a molar composition of IgG2-AB1. A hybrid dimer with dual specificity consisting of IgG anti-sheep red blood cells/AB/IgG anti-bovine red blood cells was also obtained by reacting successively both rabbit antibodies with the AB fragment. The immunologic properties (affinity for antigen, complement activation and binding to Fc receptors) of the dimeric IgG were investigated in comparison with monomeric rabbit IgG and a tetrameric IgG obtained by reaction with protein A, (IgG2-protein A1)2.