Recombinant polymeric IgG: an approach to engineering more potent antibodies.

IgM and IgG are the only classes of immunoglobulin capable of initiating the classical complement cascade. IgM, however, fixes complement much more effectively than IgG making it a more attractive Fc for some immunotherapeutic strategies. IgG, on the other hand, triggers additional effector functions mediated through gamma specific Fc receptors. Using a generalizable technique we have produced IgM-like polymers of IgG that possess both the Fc gamma receptor binding properties of IgG and the more potent complement activity of IgM.