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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

Influence of MLE on the class II MHC peptide-loading of dendritic cells.(A) Cell surface loading. HLA-DR4 expressing dendritic cells (DC) generated from the bone marrow of HLA-DR4 transgenic mice were incubated for 4 h with medium alone (left panel) or with 5 µg/ml biotinylated HA 306–318 peptide in the absence (middle panel) or presence of 250 µM AdEtOH, the model MLE compound used throughout this study (right panel). Contour plots are shown for DC after staining with anti-HLA-DR antibody (→ MHC expression) and streptavidin (→ peptide load). Mean peptide loading (MFI of streptavidin signal) is indicated. (B) CD4+ T cell response. DC from HLA-DR4tg mice (left panel) and from HLA-DR1tg mice (right panel) were pulsed for 4 h with indicated amounts of HA 306–318 peptide in the absence (open circle) and presence (closed circle) of 250 µM AdEtOH. The cells were used to challenge HA 306–318 specific, HLA-DR4-restricted 8475/94 cells and HLA-DR1-restricted EvHA/X5 T cell hybridoma cells, respectively. Background proliferation was measured in absence of peptide (dashed line).
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pone-0006811-g001: Influence of MLE on the class II MHC peptide-loading of dendritic cells.(A) Cell surface loading. HLA-DR4 expressing dendritic cells (DC) generated from the bone marrow of HLA-DR4 transgenic mice were incubated for 4 h with medium alone (left panel) or with 5 µg/ml biotinylated HA 306–318 peptide in the absence (middle panel) or presence of 250 µM AdEtOH, the model MLE compound used throughout this study (right panel). Contour plots are shown for DC after staining with anti-HLA-DR antibody (→ MHC expression) and streptavidin (→ peptide load). Mean peptide loading (MFI of streptavidin signal) is indicated. (B) CD4+ T cell response. DC from HLA-DR4tg mice (left panel) and from HLA-DR1tg mice (right panel) were pulsed for 4 h with indicated amounts of HA 306–318 peptide in the absence (open circle) and presence (closed circle) of 250 µM AdEtOH. The cells were used to challenge HA 306–318 specific, HLA-DR4-restricted 8475/94 cells and HLA-DR1-restricted EvHA/X5 T cell hybridoma cells, respectively. Background proliferation was measured in absence of peptide (dashed line).

Mentions: DC derived from the bone marrow of HLA-DR4-transgenic mice were pulsed in the presence or absence of MLE with biotinylated HA 306–318 peptide (HA), an epitope derived from the hemagglutinin protein of the influenza virus [25]. The amount of HA peptide bound to the surface of the cells was then determined by flow cytometry, performing a double staining with HLA-DR antibody and streptavidin conjugates. As shown in Fig. 1A, peptide loading was indeed strongly enhanced when MLE were present during pulsing. Compared to the control staining without any peptide (left panel) the incubation with peptide alone revealed only a marginal increase in peptide signal (middle panel). The presence of MLE, in contrast, generated a very clear peptide-specific staining particularly on the HLA-DRbright cells. The signal of bound peptide correlated directly with the HLA-DR4 expression level of the cell, confirming the specificity of the loading reaction.


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)

Influence of MLE on the class II MHC peptide-loading of dendritic cells.(A) Cell surface loading. HLA-DR4 expressing dendritic cells (DC) generated from the bone marrow of HLA-DR4 transgenic mice were incubated for 4 h with medium alone (left panel) or with 5 µg/ml biotinylated HA 306–318 peptide in the absence (middle panel) or presence of 250 µM AdEtOH, the model MLE compound used throughout this study (right panel). Contour plots are shown for DC after staining with anti-HLA-DR antibody (→ MHC expression) and streptavidin (→ peptide load). Mean peptide loading (MFI of streptavidin signal) is indicated. (B) CD4+ T cell response. DC from HLA-DR4tg mice (left panel) and from HLA-DR1tg mice (right panel) were pulsed for 4 h with indicated amounts of HA 306–318 peptide in the absence (open circle) and presence (closed circle) of 250 µM AdEtOH. The cells were used to challenge HA 306–318 specific, HLA-DR4-restricted 8475/94 cells and HLA-DR1-restricted EvHA/X5 T cell hybridoma cells, respectively. Background proliferation was measured in absence of peptide (dashed line).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2735034&req=5

pone-0006811-g001: Influence of MLE on the class II MHC peptide-loading of dendritic cells.(A) Cell surface loading. HLA-DR4 expressing dendritic cells (DC) generated from the bone marrow of HLA-DR4 transgenic mice were incubated for 4 h with medium alone (left panel) or with 5 µg/ml biotinylated HA 306–318 peptide in the absence (middle panel) or presence of 250 µM AdEtOH, the model MLE compound used throughout this study (right panel). Contour plots are shown for DC after staining with anti-HLA-DR antibody (→ MHC expression) and streptavidin (→ peptide load). Mean peptide loading (MFI of streptavidin signal) is indicated. (B) CD4+ T cell response. DC from HLA-DR4tg mice (left panel) and from HLA-DR1tg mice (right panel) were pulsed for 4 h with indicated amounts of HA 306–318 peptide in the absence (open circle) and presence (closed circle) of 250 µM AdEtOH. The cells were used to challenge HA 306–318 specific, HLA-DR4-restricted 8475/94 cells and HLA-DR1-restricted EvHA/X5 T cell hybridoma cells, respectively. Background proliferation was measured in absence of peptide (dashed line).
Mentions: DC derived from the bone marrow of HLA-DR4-transgenic mice were pulsed in the presence or absence of MLE with biotinylated HA 306–318 peptide (HA), an epitope derived from the hemagglutinin protein of the influenza virus [25]. The amount of HA peptide bound to the surface of the cells was then determined by flow cytometry, performing a double staining with HLA-DR antibody and streptavidin conjugates. As shown in Fig. 1A, peptide loading was indeed strongly enhanced when MLE were present during pulsing. Compared to the control staining without any peptide (left panel) the incubation with peptide alone revealed only a marginal increase in peptide signal (middle panel). The presence of MLE, in contrast, generated a very clear peptide-specific staining particularly on the HLA-DRbright cells. The signal of bound peptide correlated directly with the HLA-DR4 expression level of the cell, confirming the specificity of the loading reaction.

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