title: The tumoricidal activity of memory CD8+ T cells is hampered by persistent systemic antigen, but full functional capacity is regained in an antigen-free environment.
abstract: Naive T cells can be tolerized in the periphery by diverse mechanisms. However, the extent to which memory T cells are susceptible to tolerance induction is less well defined. Vaccination of mice with a minimal CTL epitope derived from human adenovirus type 5 E1A in IFA s.c. readily tolerizes naive as well as recently activated CD8(+) T cells due to the overwhelming systemic and persistent presence of the peptide. We have now studied the effect of this peptide on established memory cells, which were induced at least 50 days before by virus vaccination. Memory cells did not undergo peripheral deletion and kept their ability to produce IFN-gamma as well as their cytolytic activity in response to Ag directly ex vivo. However, memory CTL responses in virus vaccinated mice injected with peptide ceased to control tumor outgrowth. Interestingly, functional capacities were regained when T cells were transferred to an Ag-free environment in vivo as determined by their ability to reject an otherwise lethal tumor challenge. Together, these findings indicate that memory CTL responses can be functionally incapacitated, but are not, in contrast to naive or recently activated T cells, irreversibly tolerized by persistent systemic Ag, as memory T cells quickly regain effector function upon disappearance of the Ag.
authors.affiliation: Department of Immunohematology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Annemieke Th
authors.initials: AT
authors.lastname: den Boer
authors.forename: Geertje J D
authors.initials: GJ
authors.lastname: van Mierlo
authors.forename: Marieke F
authors.initials: MF
authors.lastname: Fransen
authors.forename: Cornelis J M
authors.initials: CJ
authors.lastname: Melief
authors.forename: Rienk
authors.initials: R
authors.lastname: Offringa
authors.forename: René E M
authors.initials: RE
authors.lastname: Toes
mesh_terms: D017500:Adenovirus E1A Proteins / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism*; D019264:Adoptive Transfer; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism; D007108:Immune Tolerance / Q000276:immunology; D007156:Immunologic Memory; D007279:Injections, Subcutaneous; D007399:Interphase / Q000276:immunology; D008212:Lymphocyte Depletion; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology* / Q000637:transplantation; D014412:Tumor Virus Infections / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000276:immunology
chemical_list: D017500:Adenovirus E1A Proteins; D018984:Epitopes, T-Lymphocyte; D022223:Vaccines, Subunit