Passive immunization: a method of enhancing the immune response against antigen mixtures.

Antigenic competition is known to be a widespread phenomenon when using crude extracts of antigens (e.g., Escherichia coli cytoplasmic proteins) for immunization. This non-specific form of immune suppression can be partially overcome by passive immunization with antibodies against dominant antigens (which are the suppressive molecules) before injection of the antigenic mixture. Blocking these immunodominant antigens or antigenic determinants by a passively administered antibody permits antibody responses against hitherto weakly or non-immunogenic molecules.