Relationships between relative binding affinity and electrophoretic behavior of rabbit antibodies to streptococcal carbohydrates.

After repeated intravenous injections with Group C streptococcal vaccine, most rabbit antisera were shown to contain one or more IgG antibody components, as revealed by microzone electrophoresis. A procedure for the fractionation of multiple IgG antibody components from such streptococcal antisera is described. Separation is achieved on the basis of differences in relative binding affinities of the antibody components to immunoabsorbent columns. The evidence suggests that the electrophoretic mobility, and thus the net charge of an antibody, bears a reciprocal relationship to its binding affinity for the streptococcal Group C antigens. Furthermore, the relative binding affinity affords another means to assess the functional homogeneity of streptococcal antibodies. A possible relationship between light chain variable-region subclasses and binding affinities of streptococcal antibodies is discussed.