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Allelic variation of MHC structure alters peptide ligands to induce atypical partial agonistic CD8+ T cell function.

Lim DG, Slavik JM, Bourcier K, Smith KJ, Hafler DA - J. Exp. Med. (2003)

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Immunology, Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Institutes of Medicine, Boston, MA 02115-5817, USA.

ABSTRACT
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.

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Activation of early signaling molecules and Ca2+ flux are not efficiently induced in TP60 T cells by Tax11-19–HLA-A*0205. (A) Anti–TCR ζ immunoprecipitates were prepared from lysates made from 107 KS.B (HLA-A*0201) cells alone, 107 DAH (HLA-A*0205) cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with KS.B/PBS, KS.B/F3R, KS.B/Tax11-19, DAH/PBS, DAH/F3N, or DAH/Tax11-19. Tyrosyl-phosphorylated ζ chain was detected by immunoblotting with antiphosphotyrosine antibody and the proteins were visualized by ECL. (B) Antiphosphotyrosine immunoprecipitates were prepared from lysates from 107 DAH cells alone, 107 KS.B cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with DAH/PBS, DAH/Tax11-19, DAH/F3N, KS.B/PBS, KS.B/Tax11-19, or KS.B/F3R. PLC-γ (top) or LAT (bottom) was detected by immunoblotting and the proteins were visualized by ECL. (C) TP60 T cells were stimulated with 10 μM of each peptide presented by KS.B or DAH and [Ca++]i increase in T cells was monitored. Arrows indicate the addition of peptide-pulsed APCs. One representative experiment of four is shown. N.D., not determined.
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fig6: Activation of early signaling molecules and Ca2+ flux are not efficiently induced in TP60 T cells by Tax11-19–HLA-A*0205. (A) Anti–TCR ζ immunoprecipitates were prepared from lysates made from 107 KS.B (HLA-A*0201) cells alone, 107 DAH (HLA-A*0205) cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with KS.B/PBS, KS.B/F3R, KS.B/Tax11-19, DAH/PBS, DAH/F3N, or DAH/Tax11-19. Tyrosyl-phosphorylated ζ chain was detected by immunoblotting with antiphosphotyrosine antibody and the proteins were visualized by ECL. (B) Antiphosphotyrosine immunoprecipitates were prepared from lysates from 107 DAH cells alone, 107 KS.B cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with DAH/PBS, DAH/Tax11-19, DAH/F3N, KS.B/PBS, KS.B/Tax11-19, or KS.B/F3R. PLC-γ (top) or LAT (bottom) was detected by immunoblotting and the proteins were visualized by ECL. (C) TP60 T cells were stimulated with 10 μM of each peptide presented by KS.B or DAH and [Ca++]i increase in T cells was monitored. Arrows indicate the addition of peptide-pulsed APCs. One representative experiment of four is shown. N.D., not determined.

Mentions: We further investigated this novel functional dissociation by analyzing the intracellular signaling pathways activated upon stimulation. Previous papers indicate that partial agonists can trigger only a subset of early T cell signals (29–31). Therefore, first we examined phosphorylation status of TCR-ζ chain after stimulation with different ligands. TP60 cells incubated with either unpulsed KS.B or DAH cells showed some level of constitutively phosphorylated TCR-ζ, possibly due to the basal activation status of cloned T cells. There was an increase in TCR-ζ phosphorylation after incubation with the agonistic ligands, Tax11-19–HLA-A*0201 or F3N/HLA-A*0205. However, incubation of TP60 cells with DAH cells pulsed with Tax11-19 did not significantly enhance the intensity of TCR-ζ phosphorylation (Fig. 6 A). In these experiments, we could not detect discrete bands of phosphorylated TCR-ζ chain even with the strong agonistic stimulation, which has been described previously in human as well as murine T cells (15, 29). This difference might come from the use of different antibodies and/or different experimental approaches.


Allelic variation of MHC structure alters peptide ligands to induce atypical partial agonistic CD8+ T cell function.

Lim DG, Slavik JM, Bourcier K, Smith KJ, Hafler DA - J. Exp. Med. (2003)

Activation of early signaling molecules and Ca2+ flux are not efficiently induced in TP60 T cells by Tax11-19–HLA-A*0205. (A) Anti–TCR ζ immunoprecipitates were prepared from lysates made from 107 KS.B (HLA-A*0201) cells alone, 107 DAH (HLA-A*0205) cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with KS.B/PBS, KS.B/F3R, KS.B/Tax11-19, DAH/PBS, DAH/F3N, or DAH/Tax11-19. Tyrosyl-phosphorylated ζ chain was detected by immunoblotting with antiphosphotyrosine antibody and the proteins were visualized by ECL. (B) Antiphosphotyrosine immunoprecipitates were prepared from lysates from 107 DAH cells alone, 107 KS.B cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with DAH/PBS, DAH/Tax11-19, DAH/F3N, KS.B/PBS, KS.B/Tax11-19, or KS.B/F3R. PLC-γ (top) or LAT (bottom) was detected by immunoblotting and the proteins were visualized by ECL. (C) TP60 T cells were stimulated with 10 μM of each peptide presented by KS.B or DAH and [Ca++]i increase in T cells was monitored. Arrows indicate the addition of peptide-pulsed APCs. One representative experiment of four is shown. N.D., not determined.
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Related In: Results  -  Collection

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fig6: Activation of early signaling molecules and Ca2+ flux are not efficiently induced in TP60 T cells by Tax11-19–HLA-A*0205. (A) Anti–TCR ζ immunoprecipitates were prepared from lysates made from 107 KS.B (HLA-A*0201) cells alone, 107 DAH (HLA-A*0205) cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with KS.B/PBS, KS.B/F3R, KS.B/Tax11-19, DAH/PBS, DAH/F3N, or DAH/Tax11-19. Tyrosyl-phosphorylated ζ chain was detected by immunoblotting with antiphosphotyrosine antibody and the proteins were visualized by ECL. (B) Antiphosphotyrosine immunoprecipitates were prepared from lysates from 107 DAH cells alone, 107 KS.B cells alone, or from 2 × 107 TP60 cells stimulated for 5 min with DAH/PBS, DAH/Tax11-19, DAH/F3N, KS.B/PBS, KS.B/Tax11-19, or KS.B/F3R. PLC-γ (top) or LAT (bottom) was detected by immunoblotting and the proteins were visualized by ECL. (C) TP60 T cells were stimulated with 10 μM of each peptide presented by KS.B or DAH and [Ca++]i increase in T cells was monitored. Arrows indicate the addition of peptide-pulsed APCs. One representative experiment of four is shown. N.D., not determined.
Mentions: We further investigated this novel functional dissociation by analyzing the intracellular signaling pathways activated upon stimulation. Previous papers indicate that partial agonists can trigger only a subset of early T cell signals (29–31). Therefore, first we examined phosphorylation status of TCR-ζ chain after stimulation with different ligands. TP60 cells incubated with either unpulsed KS.B or DAH cells showed some level of constitutively phosphorylated TCR-ζ, possibly due to the basal activation status of cloned T cells. There was an increase in TCR-ζ phosphorylation after incubation with the agonistic ligands, Tax11-19–HLA-A*0201 or F3N/HLA-A*0205. However, incubation of TP60 cells with DAH cells pulsed with Tax11-19 did not significantly enhance the intensity of TCR-ζ phosphorylation (Fig. 6 A). In these experiments, we could not detect discrete bands of phosphorylated TCR-ζ chain even with the strong agonistic stimulation, which has been described previously in human as well as murine T cells (15, 29). This difference might come from the use of different antibodies and/or different experimental approaches.

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Immunology, Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Institutes of Medicine, Boston, MA 02115-5817, USA.

ABSTRACT
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.

Show MeSH