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Effects of epitope modification on T cell receptor-ligand binding and antigen recognition by seven H-2Kd-restricted cytotoxic T lymphocyte clones specific for a photoreactive peptide derivative.

Kessler BM, Bassanini P, Cerottini JC, Luescher IF - J. Exp. Med. (1997)

Bottom Line: In most cases (over 80%) cytotoxicity (chromium release) and TCR-ligand binding differed by less than fivefold.The exceptions included (a) partial TCR agonists (8 cases), for which antigen recognition was five-tenfold less efficient than TCR-ligand binding, (b) TCR antagonists (2 cases), which were not recognized and capable of inhibiting recognition of the wild-type conjugate, (c) heteroclitic agonists (2 cases), for which antigen recognition was more efficient than TCR-ligand binding, and (d) one partial TCR agonist, which activated only Fas (C1)95), but not perforin/granzyme-mediated cytotoxicity.There was no correlation between these divergences and the avidity of TCR-ligand binding, indicating that other factors than binding avidity determine the nature of the CTL response.

View Article: PubMed Central - PubMed

Affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Epalinges, Switzerland.

ABSTRACT
We tested for antigen recognition and T cell receptor (TCR)-ligand binding 12 peptide derivative variants on seven H-2Kd-restricted cytotoxic T lymphocytes (CTL) clones specific for a bifunctional photoreactive derivative of the Plasmodium berghei circumsporozoite peptide 252-260 (SYIPSAEKI). The derivative contained iodo-4-azidosalicylic acid in place of PbCS S-252 and 4-azidobenzoic acid on PbCS K-259. Selective photoactivation of the N-terminal photoreactive group allowed crosslinking to Kd molecules and photoactivation of the orthogonal group to TCR. TCR photoaffinity labeling with covalent Kd-peptide derivative complexes allowed direct assessment of TCR-ligand binding on living CTL. In most cases (over 80%) cytotoxicity (chromium release) and TCR-ligand binding differed by less than fivefold. The exceptions included (a) partial TCR agonists (8 cases), for which antigen recognition was five-tenfold less efficient than TCR-ligand binding, (b) TCR antagonists (2 cases), which were not recognized and capable of inhibiting recognition of the wild-type conjugate, (c) heteroclitic agonists (2 cases), for which antigen recognition was more efficient than TCR-ligand binding, and (d) one partial TCR agonist, which activated only Fas (C1)95), but not perforin/granzyme-mediated cytotoxicity. There was no correlation between these divergences and the avidity of TCR-ligand binding, indicating that other factors than binding avidity determine the nature of the CTL response. An unexpected and novel finding was that CD8-dependent clones clearly incline more to TCR antagonism than CD8-independent ones. As there was no correlation between CD8 dependence and the avidity of TCR-ligand binding, the possibility is suggested that CD8 plays a critical role in aberrant CTL function.

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CD8 dependence and  avidities of TCR–ligand binding.  The recognition of IASA-YIPSAEK(ABA)I by the different  CTL clones was assessed in the  presence or absence of the antiCD8β mAb H35-17 or the antiCD8α mAb 53.6.72 as described  for Fig. 1. Alternatively, and as  shown in the inserts, the cloned  CTL were incubated in the absence (closed bars) or presence  (open bars) of anti-Kd mAb 208-4S with Kd-“125IASA”-YIPSAEK(ABA)I and the cell-associated radioactivity was measured  as described for Fig. 2 C. 100%  refers to the highest degree of  binding, as observed on CTL S4.
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Figure 6: CD8 dependence and avidities of TCR–ligand binding. The recognition of IASA-YIPSAEK(ABA)I by the different CTL clones was assessed in the presence or absence of the antiCD8β mAb H35-17 or the antiCD8α mAb 53.6.72 as described for Fig. 1. Alternatively, and as shown in the inserts, the cloned CTL were incubated in the absence (closed bars) or presence (open bars) of anti-Kd mAb 208-4S with Kd-“125IASA”-YIPSAEK(ABA)I and the cell-associated radioactivity was measured as described for Fig. 2 C. 100% refers to the highest degree of binding, as observed on CTL S4.

Mentions: From Fig. 3, it emerges that epitope modifications affect antigen recognition and TCR–ligand binding in a clone-specific manner. To find out whether this is accounted for by CD8, we assessed the CD8 dependence of the clones, as well as the avidity of their TCR–ligand binding. As shown in Fig. 6, the recognition of IASA-YIPSAEK(ABA)I by the different clones was inhibited by the anti-CD8β mAb H35-17 in a diverse manner. The recognition by the S1, S17, and T1 clones was barely affected, but significantly impaired for clones S4 and S15 and abolished for clones S14 and S18. Because anti-CD8 mAb can have diverse effects on CTL, we repeated these experiments using the anti-CD8α mAb 53.6.72, which binds the other chain of CD8 as well as Fab′ fragments of this mAb. Essentially the same findings were obtained (Fig. 6; data not shown), indicating that clones S14, S17, and T1 are CD8 independent, clones S14, S15, and S18 are CD8 dependent, and clone S4 is intermediate. Interestingly, TCR antagonism was observed mainly among the CD8-dependent clones (see Figs. 3 and 6).


Effects of epitope modification on T cell receptor-ligand binding and antigen recognition by seven H-2Kd-restricted cytotoxic T lymphocyte clones specific for a photoreactive peptide derivative.

Kessler BM, Bassanini P, Cerottini JC, Luescher IF - J. Exp. Med. (1997)

CD8 dependence and  avidities of TCR–ligand binding.  The recognition of IASA-YIPSAEK(ABA)I by the different  CTL clones was assessed in the  presence or absence of the antiCD8β mAb H35-17 or the antiCD8α mAb 53.6.72 as described  for Fig. 1. Alternatively, and as  shown in the inserts, the cloned  CTL were incubated in the absence (closed bars) or presence  (open bars) of anti-Kd mAb 208-4S with Kd-“125IASA”-YIPSAEK(ABA)I and the cell-associated radioactivity was measured  as described for Fig. 2 C. 100%  refers to the highest degree of  binding, as observed on CTL S4.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2196149&req=5

Figure 6: CD8 dependence and avidities of TCR–ligand binding. The recognition of IASA-YIPSAEK(ABA)I by the different CTL clones was assessed in the presence or absence of the antiCD8β mAb H35-17 or the antiCD8α mAb 53.6.72 as described for Fig. 1. Alternatively, and as shown in the inserts, the cloned CTL were incubated in the absence (closed bars) or presence (open bars) of anti-Kd mAb 208-4S with Kd-“125IASA”-YIPSAEK(ABA)I and the cell-associated radioactivity was measured as described for Fig. 2 C. 100% refers to the highest degree of binding, as observed on CTL S4.
Mentions: From Fig. 3, it emerges that epitope modifications affect antigen recognition and TCR–ligand binding in a clone-specific manner. To find out whether this is accounted for by CD8, we assessed the CD8 dependence of the clones, as well as the avidity of their TCR–ligand binding. As shown in Fig. 6, the recognition of IASA-YIPSAEK(ABA)I by the different clones was inhibited by the anti-CD8β mAb H35-17 in a diverse manner. The recognition by the S1, S17, and T1 clones was barely affected, but significantly impaired for clones S4 and S15 and abolished for clones S14 and S18. Because anti-CD8 mAb can have diverse effects on CTL, we repeated these experiments using the anti-CD8α mAb 53.6.72, which binds the other chain of CD8 as well as Fab′ fragments of this mAb. Essentially the same findings were obtained (Fig. 6; data not shown), indicating that clones S14, S17, and T1 are CD8 independent, clones S14, S15, and S18 are CD8 dependent, and clone S4 is intermediate. Interestingly, TCR antagonism was observed mainly among the CD8-dependent clones (see Figs. 3 and 6).

Bottom Line: In most cases (over 80%) cytotoxicity (chromium release) and TCR-ligand binding differed by less than fivefold.The exceptions included (a) partial TCR agonists (8 cases), for which antigen recognition was five-tenfold less efficient than TCR-ligand binding, (b) TCR antagonists (2 cases), which were not recognized and capable of inhibiting recognition of the wild-type conjugate, (c) heteroclitic agonists (2 cases), for which antigen recognition was more efficient than TCR-ligand binding, and (d) one partial TCR agonist, which activated only Fas (C1)95), but not perforin/granzyme-mediated cytotoxicity.There was no correlation between these divergences and the avidity of TCR-ligand binding, indicating that other factors than binding avidity determine the nature of the CTL response.

View Article: PubMed Central - PubMed

Affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Epalinges, Switzerland.

ABSTRACT
We tested for antigen recognition and T cell receptor (TCR)-ligand binding 12 peptide derivative variants on seven H-2Kd-restricted cytotoxic T lymphocytes (CTL) clones specific for a bifunctional photoreactive derivative of the Plasmodium berghei circumsporozoite peptide 252-260 (SYIPSAEKI). The derivative contained iodo-4-azidosalicylic acid in place of PbCS S-252 and 4-azidobenzoic acid on PbCS K-259. Selective photoactivation of the N-terminal photoreactive group allowed crosslinking to Kd molecules and photoactivation of the orthogonal group to TCR. TCR photoaffinity labeling with covalent Kd-peptide derivative complexes allowed direct assessment of TCR-ligand binding on living CTL. In most cases (over 80%) cytotoxicity (chromium release) and TCR-ligand binding differed by less than fivefold. The exceptions included (a) partial TCR agonists (8 cases), for which antigen recognition was five-tenfold less efficient than TCR-ligand binding, (b) TCR antagonists (2 cases), which were not recognized and capable of inhibiting recognition of the wild-type conjugate, (c) heteroclitic agonists (2 cases), for which antigen recognition was more efficient than TCR-ligand binding, and (d) one partial TCR agonist, which activated only Fas (C1)95), but not perforin/granzyme-mediated cytotoxicity. There was no correlation between these divergences and the avidity of TCR-ligand binding, indicating that other factors than binding avidity determine the nature of the CTL response. An unexpected and novel finding was that CD8-dependent clones clearly incline more to TCR antagonism than CD8-independent ones. As there was no correlation between CD8 dependence and the avidity of TCR-ligand binding, the possibility is suggested that CD8 plays a critical role in aberrant CTL function.

Show MeSH
Related in: MedlinePlus