title: Immunisation with an allogeneic peptide promotes the induction of antigen-specific MHC II(pos) CD4+ rat T cells demonstrating immunostimulatory properties.
abstract: BACKGROUND
  The phenomenon of T cell stimulation by MHC class II expressing (MHC II(pos)) CD4+ T cells has been intensively investigated for T cell clones but, so far, not for native T cells. The extensive use of T cell clones may explain the inconsistent outcomes of T cell-mediated antigen-presentation. Therefore, we used freshly isolated primed rat CD4+ T cells induced by immunisation with an allogeneic peptide P1, which is involved in allograft rejection.
  
  
  METHODS
  MHC II(pos) and MHC II(neg) CD4+ T cells were isolated from popliteal lymph nodes of P1-immunised Lewis rats and were purified by combining depletion and positive selection steps. Purified MHC II(pos) CD4+ T cells and MHC II(neg) CD4+ T cells (10⁵ cells per well each) were autostimulated or restimulated with P1-loaded (33 μg/ml peptide P1) and subsequently irradiated (with 20 Gy) autologous DC.
  
  
  RESULTS
  Seven days after immunisation, a small population of MHC II(pos) CD4+ T cells was detectable (approximately 8.0% of total lymph node cells), as well as a large population of MHC II(neg) CD4+ T cells (up to 45%). Antigen-specific proliferation was observed for both T cell populations but only P1-loaded MHC II(pos) CD4+ T cells presented antigen presenting cell (APC) function for P1-primed T cells. Their inability to activate unprimed T cells may be due to impaired surface expression of costimulatory molecules (CD80 and CD86).
  
  
  CONCLUSIONS
  Immunisation with the allogeneic peptide antigen P1 induced antigen-specific MHC II(pos) CD4+ rat T cells demonstrating perfect APC function for primed T cells in vitro.
authors.affiliation: Experimental Surgery, Experimental Transplantation Immunology, Clinic of General, Visceral, Vascular, and Paediatric Surgery, Surgical Clinic I, University of Würzburg Hospital, Oberdürrbacher Str. 6, D-97080 Würzburg, Germany. Otto_C@chirurgie.uni-wuerzburg.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Otto
authors.forename: André
authors.initials: A
authors.lastname: Heeg
authors.forename: Stefan
authors.initials: S
authors.lastname: Kottenmeier
authors.forename: Oliver
authors.initials: O
authors.lastname: Kuckein
authors.forename: Bianca
authors.initials: B
authors.lastname: Schneiker
authors.forename: Sabine
authors.initials: S
authors.lastname: Gahn
authors.forename: Christoph Thomas
authors.initials: CT
authors.lastname: Germer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steger
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology*; D006084:Graft Rejection / Q000276:immunology*; D007114:Immunization; D007519:Isoantigens / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D016207:Cytokines; D007519:Isoantigens; D010446:Peptide Fragments