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Mast cells and dendritic cells form synapses that facilitate antigen transfer for T cell activation.

Carroll-Portillo A, Cannon JL, te Riet J, Holmes A, Kawakami Y, Kawakami T, Cambi A, Lidke DS - J. Cell Biol. (2015)

Bottom Line: Direct cellular contact differentially regulates the secreted cytokine profile, indicating that MC modulation of DC populations is influenced by the nature of their interaction.Synapse formation requires integrin engagement and facilitates the transfer of internalized MC-specific antigen from MCs to DCs.The transferred material is ultimately processed and presented by DCs and can activate T cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, The University of New Mexico School of Medicine, Albuquerque, NM 87131.

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Activated MCs transfer internalized IgE–FcεRI to DCs through direct contact. (A) Maximum projection image from a confocal Z stack of a typical example of material transfer between an activated BMMC labeled with AF555-IgE (red) in contact with two immature BMDCs (seen in 36 of 45 cells counted across three independent experiments). Cells are fixed and labeled for actin (green) and nuclei (blue). Arrows indicate multiple occurrences of material transfer to each DC. The inset shows the actin labeling for the actMC, demonstrating actin clearance at the site of IgE–FcεRI accumulation. Image contrast in the red channel is enhanced to visualize the material transfer (puncta in the DCs) that is much lower in intensity than the MC-localized IgE. (B, top) The membrane marker GPI-GFP (green) transiently expressed in transfected BMMCs does not transfer to imDCs with the IgE-containing vesicles (red puncta). (bottom) When transiently expressed in transfected BMMCs, the endosomal marker, CD9 (green) does colocalize with the IgE-containing vesicles (red), both within the MCs and in those that have been transferred to the imDCs. White, boxed regions are enlarged and channel separated to the right of each merged image. Consistent results were acquired from two independent transfection experiments for each marker. (C) Representative images (from six independent experiments) of fixed labeling of actMCs co-incubated with imDCs. Cells were fixed after the indicated time and demonstrate colocalization of transferred material (IgE, red) with early endosomal compartments (EEA1, green), in the DCs (white boxes in merged image). The 10-min images (left) show an actMC in contact with a DC. The 30-min images (right) do not contain a MC, presumably because the interaction was lost by 30 min. All images were brightness and contrast enhanced. Bars, 10 µm.
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fig5: Activated MCs transfer internalized IgE–FcεRI to DCs through direct contact. (A) Maximum projection image from a confocal Z stack of a typical example of material transfer between an activated BMMC labeled with AF555-IgE (red) in contact with two immature BMDCs (seen in 36 of 45 cells counted across three independent experiments). Cells are fixed and labeled for actin (green) and nuclei (blue). Arrows indicate multiple occurrences of material transfer to each DC. The inset shows the actin labeling for the actMC, demonstrating actin clearance at the site of IgE–FcεRI accumulation. Image contrast in the red channel is enhanced to visualize the material transfer (puncta in the DCs) that is much lower in intensity than the MC-localized IgE. (B, top) The membrane marker GPI-GFP (green) transiently expressed in transfected BMMCs does not transfer to imDCs with the IgE-containing vesicles (red puncta). (bottom) When transiently expressed in transfected BMMCs, the endosomal marker, CD9 (green) does colocalize with the IgE-containing vesicles (red), both within the MCs and in those that have been transferred to the imDCs. White, boxed regions are enlarged and channel separated to the right of each merged image. Consistent results were acquired from two independent transfection experiments for each marker. (C) Representative images (from six independent experiments) of fixed labeling of actMCs co-incubated with imDCs. Cells were fixed after the indicated time and demonstrate colocalization of transferred material (IgE, red) with early endosomal compartments (EEA1, green), in the DCs (white boxes in merged image). The 10-min images (left) show an actMC in contact with a DC. The 30-min images (right) do not contain a MC, presumably because the interaction was lost by 30 min. All images were brightness and contrast enhanced. Bars, 10 µm.

Mentions: In addition to stimulation of signaling pathways for immune modulation, synapses between immune cells have been reported to provide a mechanism of material transfer between cells (Martín-Cófreces et al., 2011; Angus and Griffiths, 2013; Choudhuri et al., 2014). We observed that direct contact between actMCs and imDCs results in transfer of endocytosed AF555-IgE–FcεRI from the MC to the DC (Fig. 5 A). Material transfer was observed in 80% of DCs analyzed from fixed actMC–imDC samples. This material transfer was rapid, occurring within 30 min of MC activation. Direct contact was required for material transfer, as transfer was not detected in DCs that were separated from actMCs by a transwell (unpublished data). To characterize the mechanism of material transfer, we transfected MCs with glycosylphosphatidylinositol (GPI)-GFP (a membrane marker) or CD9-GFP (an exosome marker) and examined material transfer from actMCs to imDCs. Although cells expressing GPI-GFP transferred endosomal contents as expected, these complexes did not contain GPI-GFP (Fig. 5 B, top; and Video 5). CD9-GFP, on the other hand, colocalized with the polarized vesicles and cotransferred with fluorescent IgE to imDCs (Fig. 5 B, bottom; and Video 6). The transferred MC endosomal contents in imDCs also colocalized with the early endosomal marker, EEA1, indicating that transferred material moves through the DC endosomal pathway at least to some extent (Fig. 5 C).


Mast cells and dendritic cells form synapses that facilitate antigen transfer for T cell activation.

Carroll-Portillo A, Cannon JL, te Riet J, Holmes A, Kawakami Y, Kawakami T, Cambi A, Lidke DS - J. Cell Biol. (2015)

Activated MCs transfer internalized IgE–FcεRI to DCs through direct contact. (A) Maximum projection image from a confocal Z stack of a typical example of material transfer between an activated BMMC labeled with AF555-IgE (red) in contact with two immature BMDCs (seen in 36 of 45 cells counted across three independent experiments). Cells are fixed and labeled for actin (green) and nuclei (blue). Arrows indicate multiple occurrences of material transfer to each DC. The inset shows the actin labeling for the actMC, demonstrating actin clearance at the site of IgE–FcεRI accumulation. Image contrast in the red channel is enhanced to visualize the material transfer (puncta in the DCs) that is much lower in intensity than the MC-localized IgE. (B, top) The membrane marker GPI-GFP (green) transiently expressed in transfected BMMCs does not transfer to imDCs with the IgE-containing vesicles (red puncta). (bottom) When transiently expressed in transfected BMMCs, the endosomal marker, CD9 (green) does colocalize with the IgE-containing vesicles (red), both within the MCs and in those that have been transferred to the imDCs. White, boxed regions are enlarged and channel separated to the right of each merged image. Consistent results were acquired from two independent transfection experiments for each marker. (C) Representative images (from six independent experiments) of fixed labeling of actMCs co-incubated with imDCs. Cells were fixed after the indicated time and demonstrate colocalization of transferred material (IgE, red) with early endosomal compartments (EEA1, green), in the DCs (white boxes in merged image). The 10-min images (left) show an actMC in contact with a DC. The 30-min images (right) do not contain a MC, presumably because the interaction was lost by 30 min. All images were brightness and contrast enhanced. Bars, 10 µm.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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fig5: Activated MCs transfer internalized IgE–FcεRI to DCs through direct contact. (A) Maximum projection image from a confocal Z stack of a typical example of material transfer between an activated BMMC labeled with AF555-IgE (red) in contact with two immature BMDCs (seen in 36 of 45 cells counted across three independent experiments). Cells are fixed and labeled for actin (green) and nuclei (blue). Arrows indicate multiple occurrences of material transfer to each DC. The inset shows the actin labeling for the actMC, demonstrating actin clearance at the site of IgE–FcεRI accumulation. Image contrast in the red channel is enhanced to visualize the material transfer (puncta in the DCs) that is much lower in intensity than the MC-localized IgE. (B, top) The membrane marker GPI-GFP (green) transiently expressed in transfected BMMCs does not transfer to imDCs with the IgE-containing vesicles (red puncta). (bottom) When transiently expressed in transfected BMMCs, the endosomal marker, CD9 (green) does colocalize with the IgE-containing vesicles (red), both within the MCs and in those that have been transferred to the imDCs. White, boxed regions are enlarged and channel separated to the right of each merged image. Consistent results were acquired from two independent transfection experiments for each marker. (C) Representative images (from six independent experiments) of fixed labeling of actMCs co-incubated with imDCs. Cells were fixed after the indicated time and demonstrate colocalization of transferred material (IgE, red) with early endosomal compartments (EEA1, green), in the DCs (white boxes in merged image). The 10-min images (left) show an actMC in contact with a DC. The 30-min images (right) do not contain a MC, presumably because the interaction was lost by 30 min. All images were brightness and contrast enhanced. Bars, 10 µm.
Mentions: In addition to stimulation of signaling pathways for immune modulation, synapses between immune cells have been reported to provide a mechanism of material transfer between cells (Martín-Cófreces et al., 2011; Angus and Griffiths, 2013; Choudhuri et al., 2014). We observed that direct contact between actMCs and imDCs results in transfer of endocytosed AF555-IgE–FcεRI from the MC to the DC (Fig. 5 A). Material transfer was observed in 80% of DCs analyzed from fixed actMC–imDC samples. This material transfer was rapid, occurring within 30 min of MC activation. Direct contact was required for material transfer, as transfer was not detected in DCs that were separated from actMCs by a transwell (unpublished data). To characterize the mechanism of material transfer, we transfected MCs with glycosylphosphatidylinositol (GPI)-GFP (a membrane marker) or CD9-GFP (an exosome marker) and examined material transfer from actMCs to imDCs. Although cells expressing GPI-GFP transferred endosomal contents as expected, these complexes did not contain GPI-GFP (Fig. 5 B, top; and Video 5). CD9-GFP, on the other hand, colocalized with the polarized vesicles and cotransferred with fluorescent IgE to imDCs (Fig. 5 B, bottom; and Video 6). The transferred MC endosomal contents in imDCs also colocalized with the early endosomal marker, EEA1, indicating that transferred material moves through the DC endosomal pathway at least to some extent (Fig. 5 C).

Bottom Line: Direct cellular contact differentially regulates the secreted cytokine profile, indicating that MC modulation of DC populations is influenced by the nature of their interaction.Synapse formation requires integrin engagement and facilitates the transfer of internalized MC-specific antigen from MCs to DCs.The transferred material is ultimately processed and presented by DCs and can activate T cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, The University of New Mexico School of Medicine, Albuquerque, NM 87131.

Show MeSH
Related in: MedlinePlus