Allelic variation of MHC structure alters peptide ligands to induce atypical partial agonistic CD8+ T cell function.
T cell receptors recognize small changes in peptide ligands leading to different T cell responses. Here, we analyzed a panel of HLA-A2-Tax11-19 reactive T cell clones to examine how small allelic variations of MHC molecules could alter the functional outcome of antigen recognition. Similar to the effects induced by antigenic altered peptide ligands, weak or partial agonistic T cell functions were identified in individual T cell clones with the recognition of MHC-altered peptide ligands (MAPLs). Interestingly, one subtype of HLA-A2 molecules induced an unusual type of partial agonistic function; proliferation without cytotoxicity. Modeling of crystallographic data indicated that polymorphic amino acids in the HLA-A2 peptide binding groove, especially the D-pocket, were responsible for this partial agonism. Reciprocal mutations of the Tax peptide side chain engaging the D-pocket indeed restored the agonist functions of the MHC-peptide complex. Whereas early intracellular signaling events were not efficiently induced by these MAPLs, phosphorylated c-Jun slowly accumulated with sustained long-term expression. These data indicate that MAPLs can induce atypical partial agonistic T cell function through structural and biochemical mechanisms similar to altered peptide ligands.
Lim
Dong-Gyun
DG
Laboratory of Molecular Immunology, Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Institutes of Medicine, Boston, MA 02115-5817, USA.
Slavik
Jacqueline M
JM
Bourcier
Katarzyna
K
Smith
Kathrine J
KJ
Hafler
David A
DA
D000483:Alleles; D001665:Binding Sites; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D016356:Gene Products, tax / Q000378:metabolism; D014644:Genetic Variation; D015789:HLA-A2 Antigen / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D006801:Humans; D008024:Ligands; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D011110:Polymorphism, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism
D016356:Gene Products, tax; D015789:HLA-A2 Antigen; D008024:Ligands; D010446:Peptide Fragments; D016755:Proto-Oncogene Proteins c-jun