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Nonprecipitating and electrophoretically restricted antibodies to carbohydrate of group A Streptococcus in the rat.

Hyperimmunization of Sprague-Dawley rats with group A streptococcal vaccine elicited both precipitating and nonprecipitating antibodies to the group-specific carbohydrate of the Streptococcus. The occurrence of nonprecipitating antibodies in the immune response of the rat appeared to be genetically influenced by selective inbreeding that causes a low precipitin response. A number of rats responded to immunization by producing electrophoretically restricted antibody components. This restriction in light-chain heterogeneity confirmed by polyacrylamide gel electrophoresis of isolated antibody is apparently genetically influenced and capable of recall after extended periods of nonimmunization. Recently, hyperimmunization of rabbits [1], chickens [2], and rats [3] with streptococcal vaccines has been shown to stimulate the production of large quantities of precipitating antibody. Not infrequently, however, the response to the vaccines of a number of rabbits consisted predominately of nonprecipitating antibody [1]. Aware of this phenomenon and faced with the discrepancies encountered in our own system, we conducted a careful analysis of immune sera from adult Sprague-Dawley rats hyperimmunized with vaccine derived from group A Streptococcus. The occurrence and subsequent isolation of nonprecipitating antibodies was suggested by abnormal