acquired immunity active immunity antibody antigen artificial immunity congenital immunity familial immunity immunity immunity theory immunization therapy immunochemistry immunology immunotherapy inherent immunity inherited immunity natural immunity nonspecific immunity nonsusceptibility to disease opsonic immunity passive immunity patch test phagocytic immunity racial immunity resistance scratch test serotherapeutics serotherapy serum therapy side-chain theory specific immunity toxin-antitoxin immunity toxin-antitoxin immunization tuberculin test vaccine therapy vaccinotherapy