The Puzzle of Passive Immunity

To the Editor: “Passive immunity” is defined as immunologic protection by factors not produced by the organism itself. In general, the term refers to the receipt of immunoglobulin, although such processes as neutrophil transfusions, for example, could also be said to confer passive immunity. The salient feature of passive immunity is that it lasts only as long as the administered factor remains in sufficient quantity in the recipient. The puzzle arises when Jerne's network hypothesis is considered.¹ Burdette and Schwartz's review of idiotypic networks² outlined what is currently known about idiotypic interactions. According to their description, exogenous antibody conferring passive.