title: Nature of "memory" in T-cell mediated antibacterial immunity: cellular parameters that distinguish between the active immune response and a state of "memory".
abstract: Immunizing infection in mice with Listeria monocytogenes resulted in the generation of two distinct states of immunological reactivity. There was generated (i) a short-lived state of active immunity that functioned to urgently eliminate the infection organism from the tissues and (ii) a long-lives state of increased immunological potential that enabled the host to respond to seconday infection in an accelerated manner. Short-lived active immunity was mediated by replicating T cells and expressed by activated macrophages, and it ended when these cell types disappeared from the tissue soon after complete elimination of the parasite. Long-lived immunological protential was associated with a persistent level of delayed sensitivity and with the presence of a small number of nonreplicating protective T cells. It is suggested that the state of delayed sensitivity represents a state of immunological T-cell memory of the cell-mediated type.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007111:Immunity, Cellular; D007117:Immunization, Secondary; D008089:Listeria monocytogenes; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008806:Mice, Inbred AKR; D008809:Mice, Inbred C3H; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial