COMPARISON OF SURFACE-PROPERTIES OF HUMAN-IGA, IGE, IGG AND IGM ANTIBODIES WITH IDENTICAL AND DIFFERENT SPECIFICITIES

In this paper, the authors report the use of liquid-liquid partition c hromatography (LLPC) in an aqueous polyethylene glycol (PEG)/dextran t wo-phase system to compare the surface properties (partition propertie s) of human antibodies and fragments thereof. The surface properties o f all the monoclonal antibodies of different classes and subclasses in vestigated were within the same broad range as that observed for the p olyclonal antibodies and no relationship was found between the exposed surfaces of the immunoglobulins (Ig) and their heavy chain isotype, M oreover, Fc fragments from various IgG1, 2 and 4 myeloma proteins were found to exhibit similar surface properties. Employing chimeric antib odies with identical variable regions the authors found that intact Ig G1, 2 and 4 displayed identical surface properties, while the correspo nding IgA1, IgA2, IgC3, IgE and IgM antibodies differed both from each other and from the IgGs. The surface properties of chimeric IgG3 coul d be made similar to those of the IgG1, 2 and 4 chimers by partially r educing the length of the hinge section, but new differences in surfac e properties appeared when their hinges were of similar length, Thus, LLPC can be used to detect differences or similarities in the surface properties of the antigen-binding regions as well as the Fc part in th e various isotypes. This can shed light on biological activities such as antigen binding and effector function.