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Enhancement of tumour-specific immune responses in vivo by 'MHC loading-enhancer' (MLE).

Dickhaut K, Hoepner S, Eckhard J, Wiesmueller KH, Schindler L, Jung G, Falk K, Roetzschke O - PLoS ONE (2009)

Bottom Line: Their enhancing effect on the immune response was demonstrated here with an antigen from the influenza virus and tumour associated antigens (TAA) derived from the NY-ESO-1 protein.The application of these antigens in combination with adamantane ethanol (AdEtOH), an MLE compound active on human HLA-DR molecules, significantly increased the frequency of antigen-specific CD4+ T cells in mice transgenic for the human MHC II molecule.Notably, the effect was evident only with the MLE-susceptible HLA-DR molecule and not with murine MHC II molecules non-susceptible for the catalytic effect of the MLE.

View Article: PubMed Central - PubMed

Affiliation: Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.

ABSTRACT

Background: Class II MHC molecules (MHC II) are cell surface receptors displaying short protein fragments for the surveillance by CD4+ T cells. Antigens therefore have to be loaded onto this receptor in order to induce productive immune responses. On the cell surface, most MHC II molecules are either occupied by ligands or their binding cleft has been blocked by the acquisition of a non-receptive state. Direct loading with antigens, as required during peptide vaccinations, is therefore hindered.

Principal findings: Here we show, that the in vivo response of CD4+ T cells can be improved, when the antigens are administered together with 'MHC-loading enhancer' (MLE). MLE are small catalytic compounds able to open up the MHC binding site by triggering ligand-release and stabilizing the receptive state. Their enhancing effect on the immune response was demonstrated here with an antigen from the influenza virus and tumour associated antigens (TAA) derived from the NY-ESO-1 protein. The application of these antigens in combination with adamantane ethanol (AdEtOH), an MLE compound active on human HLA-DR molecules, significantly increased the frequency of antigen-specific CD4+ T cells in mice transgenic for the human MHC II molecule. Notably, the effect was evident only with the MLE-susceptible HLA-DR molecule and not with murine MHC II molecules non-susceptible for the catalytic effect of the MLE.

Conclusion: MLE can specifically increase the potency of a vaccine by facilitating the efficient transfer of the antigen onto the MHC molecule. They may therefore open a new way to improve vaccination efficacy and tumour-immunotherapy.

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Related in: MedlinePlus

MLE enhances the T cell response against NY-ESO-1 derived epitopes.(A) Cell surface loading of NY-ESO-1 epitopes. L929 fibroblasts transfected with HLA-DR1 (left panel) or HLA-DR4 (right panel) were incubated for 4 h with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. Loading was performed in the absence (closed circles) or presence (open circles) of 250 µM AdEtOH. Non-transfected L929 cells were used as a negative control (left side). Peptide loading was determined by analyzing the mean fluorescence of the streptavidin-signal gated on a distinct expression of HLA-DR. Background fluorescence was detected in the absence of biotinylated peptide (dashed line). (B) Detection of tumour-specific T cell response in vivo. Groups of HLA-DR1tg (left panel, n = 13) or HLA-DR4tg (right panel, n = 10) mice were s.c. primed with 5 µg of the respective NY-ESO-1 epitopes in IFA/CpG supplemented with or without AdEtOH. 12 days after vaccination, 1×106 Lymph node cells were incubated with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. IFNγ-detection was carried out 48 hrs later using an Elispot assay and summarized data were analyzed using student's t test.
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pone-0006811-g004: MLE enhances the T cell response against NY-ESO-1 derived epitopes.(A) Cell surface loading of NY-ESO-1 epitopes. L929 fibroblasts transfected with HLA-DR1 (left panel) or HLA-DR4 (right panel) were incubated for 4 h with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. Loading was performed in the absence (closed circles) or presence (open circles) of 250 µM AdEtOH. Non-transfected L929 cells were used as a negative control (left side). Peptide loading was determined by analyzing the mean fluorescence of the streptavidin-signal gated on a distinct expression of HLA-DR. Background fluorescence was detected in the absence of biotinylated peptide (dashed line). (B) Detection of tumour-specific T cell response in vivo. Groups of HLA-DR1tg (left panel, n = 13) or HLA-DR4tg (right panel, n = 10) mice were s.c. primed with 5 µg of the respective NY-ESO-1 epitopes in IFA/CpG supplemented with or without AdEtOH. 12 days after vaccination, 1×106 Lymph node cells were incubated with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. IFNγ-detection was carried out 48 hrs later using an Elispot assay and summarized data were analyzed using student's t test.

Mentions: Multiple NY-ESO-1-derived epitopes have been reported capable of provoking CD4+ T cell reponses [28]–[30]. As various forms of cancer cells express NY-ESO-1, these epitopes may therefore represent promising candidates for cancer vaccines. Among those were NY-ESO-1 89–101, which can be presented on HLA-DR1 [31], and the HLA-DR4-restricted NY-ESO-1 119–143 epitope [28], [32]. As both allelic HLA-DR variants are sensitive to adamantyl-mediated ligand-exchange [16], we determined the impact of AdEtOH on these tumour associated antigens (TAA) in vitro, using HLA-DR transfected fibroblasts (Fig. 4A). Both epitopes can be loaded onto the surface of cells expressing the relevant HLA-DR molecules whereas no signal is observed in absence of the human MHC class II molecules. Furthermore, adding MLE to the loading procedure leads to a strong increase of NY-ESO-1 89-101 bound to HLA-DR1 (left panels) and to a lower extent also of NY-ESO-1 119–143 bound to HLA-DR4 (right panels).


Enhancement of tumour-specific immune responses in vivo by 'MHC loading-enhancer' (MLE).

Dickhaut K, Hoepner S, Eckhard J, Wiesmueller KH, Schindler L, Jung G, Falk K, Roetzschke O - PLoS ONE (2009)

MLE enhances the T cell response against NY-ESO-1 derived epitopes.(A) Cell surface loading of NY-ESO-1 epitopes. L929 fibroblasts transfected with HLA-DR1 (left panel) or HLA-DR4 (right panel) were incubated for 4 h with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. Loading was performed in the absence (closed circles) or presence (open circles) of 250 µM AdEtOH. Non-transfected L929 cells were used as a negative control (left side). Peptide loading was determined by analyzing the mean fluorescence of the streptavidin-signal gated on a distinct expression of HLA-DR. Background fluorescence was detected in the absence of biotinylated peptide (dashed line). (B) Detection of tumour-specific T cell response in vivo. Groups of HLA-DR1tg (left panel, n = 13) or HLA-DR4tg (right panel, n = 10) mice were s.c. primed with 5 µg of the respective NY-ESO-1 epitopes in IFA/CpG supplemented with or without AdEtOH. 12 days after vaccination, 1×106 Lymph node cells were incubated with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. IFNγ-detection was carried out 48 hrs later using an Elispot assay and summarized data were analyzed using student's t test.
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Related In: Results  -  Collection

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pone-0006811-g004: MLE enhances the T cell response against NY-ESO-1 derived epitopes.(A) Cell surface loading of NY-ESO-1 epitopes. L929 fibroblasts transfected with HLA-DR1 (left panel) or HLA-DR4 (right panel) were incubated for 4 h with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. Loading was performed in the absence (closed circles) or presence (open circles) of 250 µM AdEtOH. Non-transfected L929 cells were used as a negative control (left side). Peptide loading was determined by analyzing the mean fluorescence of the streptavidin-signal gated on a distinct expression of HLA-DR. Background fluorescence was detected in the absence of biotinylated peptide (dashed line). (B) Detection of tumour-specific T cell response in vivo. Groups of HLA-DR1tg (left panel, n = 13) or HLA-DR4tg (right panel, n = 10) mice were s.c. primed with 5 µg of the respective NY-ESO-1 epitopes in IFA/CpG supplemented with or without AdEtOH. 12 days after vaccination, 1×106 Lymph node cells were incubated with titrated amounts of NY-ESO-1 89–101 or NY-ESO-1 119–143, respectively. IFNγ-detection was carried out 48 hrs later using an Elispot assay and summarized data were analyzed using student's t test.
Mentions: Multiple NY-ESO-1-derived epitopes have been reported capable of provoking CD4+ T cell reponses [28]–[30]. As various forms of cancer cells express NY-ESO-1, these epitopes may therefore represent promising candidates for cancer vaccines. Among those were NY-ESO-1 89–101, which can be presented on HLA-DR1 [31], and the HLA-DR4-restricted NY-ESO-1 119–143 epitope [28], [32]. As both allelic HLA-DR variants are sensitive to adamantyl-mediated ligand-exchange [16], we determined the impact of AdEtOH on these tumour associated antigens (TAA) in vitro, using HLA-DR transfected fibroblasts (Fig. 4A). Both epitopes can be loaded onto the surface of cells expressing the relevant HLA-DR molecules whereas no signal is observed in absence of the human MHC class II molecules. Furthermore, adding MLE to the loading procedure leads to a strong increase of NY-ESO-1 89-101 bound to HLA-DR1 (left panels) and to a lower extent also of NY-ESO-1 119–143 bound to HLA-DR4 (right panels).

Bottom Line: Their enhancing effect on the immune response was demonstrated here with an antigen from the influenza virus and tumour associated antigens (TAA) derived from the NY-ESO-1 protein.The application of these antigens in combination with adamantane ethanol (AdEtOH), an MLE compound active on human HLA-DR molecules, significantly increased the frequency of antigen-specific CD4+ T cells in mice transgenic for the human MHC II molecule.Notably, the effect was evident only with the MLE-susceptible HLA-DR molecule and not with murine MHC II molecules non-susceptible for the catalytic effect of the MLE.

View Article: PubMed Central - PubMed

Affiliation: Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.

ABSTRACT

Background: Class II MHC molecules (MHC II) are cell surface receptors displaying short protein fragments for the surveillance by CD4+ T cells. Antigens therefore have to be loaded onto this receptor in order to induce productive immune responses. On the cell surface, most MHC II molecules are either occupied by ligands or their binding cleft has been blocked by the acquisition of a non-receptive state. Direct loading with antigens, as required during peptide vaccinations, is therefore hindered.

Principal findings: Here we show, that the in vivo response of CD4+ T cells can be improved, when the antigens are administered together with 'MHC-loading enhancer' (MLE). MLE are small catalytic compounds able to open up the MHC binding site by triggering ligand-release and stabilizing the receptive state. Their enhancing effect on the immune response was demonstrated here with an antigen from the influenza virus and tumour associated antigens (TAA) derived from the NY-ESO-1 protein. The application of these antigens in combination with adamantane ethanol (AdEtOH), an MLE compound active on human HLA-DR molecules, significantly increased the frequency of antigen-specific CD4+ T cells in mice transgenic for the human MHC II molecule. Notably, the effect was evident only with the MLE-susceptible HLA-DR molecule and not with murine MHC II molecules non-susceptible for the catalytic effect of the MLE.

Conclusion: MLE can specifically increase the potency of a vaccine by facilitating the efficient transfer of the antigen onto the MHC molecule. They may therefore open a new way to improve vaccination efficacy and tumour-immunotherapy.

Show MeSH
Related in: MedlinePlus