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T cells at the site of autoimmune inflammation show increased potential for trogocytosis.

Haastert B, Mellanby RJ, Anderton SM, O'Connor RA - PLoS ONE (2013)

Bottom Line: During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites.Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation.Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, United Kingdom.

ABSTRACT
CD4+ T cells acquire membrane fragments from antigen-presenting-cells via a process termed trogocytosis. Identifying which CD4+ T cells undergo trogocytosis in co-culture with Ag-loaded APC can enrich for antigen-reactive T cells without knowledge of their fine specificity or cytokine-production profiles. We sought to assess the suitability of this method to identify disease relevant effector and regulatory T cells during autoimmune inflammation. Trogocytosis efficiently identified MBP-reactive T cells in vitro and ex-vivo following immunization. However, Foxp3+ regulatory T cells constitutively displayed a higher rate of trogocytosis than their Foxp3- counterparts which limits the potential of trogocytosis to identify antigen-reactive Treg cells. During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites. Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation. Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

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MBP-reactive T cells rapidly acquire plasma membrane fragments from APC upon activation.(A–E) Biotinylated B10.PL splenocytes (CD45.1−) were co-cultured with Tg4 T cells (CD45.1+) in the presence or absence of graded concentrations of Ac1-9(4Tyr) membrane transfer to CD45.1+ Tg4 T cells was detected by staining with SA-APC. (B) Acquisition of biotinylated membrane fragments by Tg4 T cells co-cultured in the absence (middle panel) or presence (right hand panel) of 1 µM 4Tyr for 1 h. (C) Acquisition of biotinylated membrane fragments by Tg4 T cells across a dose range of 4Tyr after overnight culture. (D) Detection of biotinylated membrane fragments and CD69 on Tg4T cells cultured in the presence or absence of 4Tyr. E) CD69 expression in SA+ Tg4 T cells in the presence or absence of Ag, error bars are SD, ***, p<0.001.Data shown is from one experiment representative of 3 similar experiments.
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pone-0081404-g001: MBP-reactive T cells rapidly acquire plasma membrane fragments from APC upon activation.(A–E) Biotinylated B10.PL splenocytes (CD45.1−) were co-cultured with Tg4 T cells (CD45.1+) in the presence or absence of graded concentrations of Ac1-9(4Tyr) membrane transfer to CD45.1+ Tg4 T cells was detected by staining with SA-APC. (B) Acquisition of biotinylated membrane fragments by Tg4 T cells co-cultured in the absence (middle panel) or presence (right hand panel) of 1 µM 4Tyr for 1 h. (C) Acquisition of biotinylated membrane fragments by Tg4 T cells across a dose range of 4Tyr after overnight culture. (D) Detection of biotinylated membrane fragments and CD69 on Tg4T cells cultured in the presence or absence of 4Tyr. E) CD69 expression in SA+ Tg4 T cells in the presence or absence of Ag, error bars are SD, ***, p<0.001.Data shown is from one experiment representative of 3 similar experiments.

Mentions: Several studies have described the process of membrane exchange between APCs and T cells upon cell-to-cell contact as an antigen-specific phenomenon [1], [16]. To assess trogocytosis upon antigenic stimulation we co-cultured CD45.1+CD4+ T cells from Tg4 mice (which express a TCR specific for the MBP Ac1-9 in association with Au) with CD45.1− peptide-pulsed biotinylated APC (Schematic Fig. 1A). Although Ac1-9 is the immunodominant T cell epitope in MBP it forms an unstable complex with Au[17] To ensure efficient Ag-presentation after peptide pulsing the altered peptide ligand Ac1-9 (4Tyr) which has an increased affinity for Au[17] was used throughout this study. We found that the acquisition of biotinylated membrane patches by CD45.1+CD4+ T cells occurred in an antigen-dependent manner (Fig. 1B) and that the trogocytosis rate related to the antigen concentration (Fig. 1C). Co-staining for CD69 as a marker of activation highlighted the close relationship between the cellular activation status and trogocytosis efficiency (Fig. 1D/E).


T cells at the site of autoimmune inflammation show increased potential for trogocytosis.

Haastert B, Mellanby RJ, Anderton SM, O'Connor RA - PLoS ONE (2013)

MBP-reactive T cells rapidly acquire plasma membrane fragments from APC upon activation.(A–E) Biotinylated B10.PL splenocytes (CD45.1−) were co-cultured with Tg4 T cells (CD45.1+) in the presence or absence of graded concentrations of Ac1-9(4Tyr) membrane transfer to CD45.1+ Tg4 T cells was detected by staining with SA-APC. (B) Acquisition of biotinylated membrane fragments by Tg4 T cells co-cultured in the absence (middle panel) or presence (right hand panel) of 1 µM 4Tyr for 1 h. (C) Acquisition of biotinylated membrane fragments by Tg4 T cells across a dose range of 4Tyr after overnight culture. (D) Detection of biotinylated membrane fragments and CD69 on Tg4T cells cultured in the presence or absence of 4Tyr. E) CD69 expression in SA+ Tg4 T cells in the presence or absence of Ag, error bars are SD, ***, p<0.001.Data shown is from one experiment representative of 3 similar experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852262&req=5

pone-0081404-g001: MBP-reactive T cells rapidly acquire plasma membrane fragments from APC upon activation.(A–E) Biotinylated B10.PL splenocytes (CD45.1−) were co-cultured with Tg4 T cells (CD45.1+) in the presence or absence of graded concentrations of Ac1-9(4Tyr) membrane transfer to CD45.1+ Tg4 T cells was detected by staining with SA-APC. (B) Acquisition of biotinylated membrane fragments by Tg4 T cells co-cultured in the absence (middle panel) or presence (right hand panel) of 1 µM 4Tyr for 1 h. (C) Acquisition of biotinylated membrane fragments by Tg4 T cells across a dose range of 4Tyr after overnight culture. (D) Detection of biotinylated membrane fragments and CD69 on Tg4T cells cultured in the presence or absence of 4Tyr. E) CD69 expression in SA+ Tg4 T cells in the presence or absence of Ag, error bars are SD, ***, p<0.001.Data shown is from one experiment representative of 3 similar experiments.
Mentions: Several studies have described the process of membrane exchange between APCs and T cells upon cell-to-cell contact as an antigen-specific phenomenon [1], [16]. To assess trogocytosis upon antigenic stimulation we co-cultured CD45.1+CD4+ T cells from Tg4 mice (which express a TCR specific for the MBP Ac1-9 in association with Au) with CD45.1− peptide-pulsed biotinylated APC (Schematic Fig. 1A). Although Ac1-9 is the immunodominant T cell epitope in MBP it forms an unstable complex with Au[17] To ensure efficient Ag-presentation after peptide pulsing the altered peptide ligand Ac1-9 (4Tyr) which has an increased affinity for Au[17] was used throughout this study. We found that the acquisition of biotinylated membrane patches by CD45.1+CD4+ T cells occurred in an antigen-dependent manner (Fig. 1B) and that the trogocytosis rate related to the antigen concentration (Fig. 1C). Co-staining for CD69 as a marker of activation highlighted the close relationship between the cellular activation status and trogocytosis efficiency (Fig. 1D/E).

Bottom Line: During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites.Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation.Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, United Kingdom.

ABSTRACT
CD4+ T cells acquire membrane fragments from antigen-presenting-cells via a process termed trogocytosis. Identifying which CD4+ T cells undergo trogocytosis in co-culture with Ag-loaded APC can enrich for antigen-reactive T cells without knowledge of their fine specificity or cytokine-production profiles. We sought to assess the suitability of this method to identify disease relevant effector and regulatory T cells during autoimmune inflammation. Trogocytosis efficiently identified MBP-reactive T cells in vitro and ex-vivo following immunization. However, Foxp3+ regulatory T cells constitutively displayed a higher rate of trogocytosis than their Foxp3- counterparts which limits the potential of trogocytosis to identify antigen-reactive Treg cells. During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites. Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation. Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

Show MeSH
Related in: MedlinePlus