title: Cutting edge: memory CD8 T cell compartment grows in size with immunological experience but nevertheless can lose function.
abstract: The size of the adaptive immune system is considered to be kept constant by the attrition of pre-existing memory. However, recently it was shown that the CD8 memory compartment can grow in size and the number of pre-existing memory is largely preserved, predicting that pre-existing immunity should be maintained (Vezys et al.; Nature 457: 196-199). Experimental proof for this assumption is still lacking. We address this question in the Listeria monocytogenes (L.m.) infection model and confirm the growth of size of the memory compartment by subsequent vaccination with modified vaccinia virus Ankara. We also find only modest attrition of pre-existing L.m.-specific memory CD8 T cells. However, pre-existing protective immunity toward L.m. is not preserved. Pre-existing L.m.-specific effector-memory cells, in contrast to central memory cells, become altered, and this results in a significant loss of pre-existing protective immunity. Our findings are clinically relevant for vaccines introducing new CD8 memory cells in high numbers, as this might influence pre-existing immunity.
authors.affiliation: Institute for Medical Microbiology, Immunology, and Hygiene, Technical University Munich, 81675 Munich, Germany.
authors.forename: Katharina M
authors.initials: KM
authors.lastname: Huster
authors.forename: Christian
authors.initials: C
authors.lastname: Stemberger
authors.forename: Georg
authors.initials: G
authors.lastname: Gasteiger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kastenmüller
authors.forename: Ingo
authors.initials: I
authors.lastname: Drexler
authors.forename: Dirk H
authors.initials: DH
authors.lastname: Busch
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D007156:Immunologic Memory / Q000276:immunology*; D008089:Listeria monocytogenes / Q000276:immunology; D008088:Listeriosis / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D014611:Vaccination; D014612:Vaccines / Q000276:immunology*; D014616:Vaccinia virus / Q000276:immunology
chemical_list: D014612:Vaccines