title: Allopeptide-specific CD4(+) T cells facilitate the differentiation of directly alloreactive graft-infiltrating CD8(+) T Cells.
abstract: To investigate the mechanism of CD4(+) T-cell help during the activation and differentiation of directly alloreactive CD8(+) T cells, we examined the development of obliterative airways disease (OAD) following transplantation of airways into fully mismatched recipient mice deficient in CD4(+) T cells. BALB/c trachea allografts became fibrosed significantly less frequently in B6 CD4(-/-) recipients as compared to wildtype controls. Furthermore, class I-directed cytotoxicity failed to develop in the absence of CD4(+) T cells. The infiltration of graft tissue by primed L(d)-specific directly alloreactive 2C CD8(+) T cells was not found to depend on the presence of CD4(+) T cells. Nevertheless, graft-infiltrating 2C CD8(+) T cells failed to express CD69 and granzyme B when CD4(+) T-cell help was unavailable. Importantly, reconstitution of B6 CD4(-/-) recipient mice with graft peptide-specific TCR-Tg CD4(+) T cells (OT-II or TEa) capable of recognizing antigen only on recipient APC allowed for full expression of CD69 and granzyme B by the directly alloreactive CD8(+) T cells and restored the capacity of recipients to reject their allografts. These results demonstrate that indirectly alloreactive CD4(+) T cells ensure the optimal activation and differentiation of graft-infiltrating directly alloreactive CD8(+) T cells independent of donor APC recognition.
authors.affiliation: Department of Medicine, and Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Richards
authors.forename: N
authors.initials: N
authors.lastname: Zhang
authors.forename: S L
authors.initials: SL
authors.lastname: Dalheimer
authors.forename: D L
authors.initials: DL
authors.lastname: Mueller
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D015704:CD4 Antigens / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014184:Transplantation, Homologous / Q000276:immunology* / Q000473:pathology; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D037181:Lectins, C-Type; D000099192:CD69 Antigens