Altered major histocompatibility complex class II peptide loading in H2-O-deficient mice

Perraudeau, Mohini; Taylor, Philip Russel; Stauss, Hans J.; Lindstedt, Ragnar; Bygrave, Anne E.; Pappin, Darryl; Ellmerich, Stéphan; Whitten, Angela; Rahman, Dinah; Cañas, Benito; Walport, Mark J.; Botto, Marina; Altmann, Daniel M.

doi:10.1002/1521-4141(200010)30:10<2871::aid-immu2871>3.0.co;2-b

Cited by 46 publications

(55 citation statements)

References 37 publications

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“…DR1-biotin CLIP complexes were formed by incubation of 500 nM DR1 with 5 M biotin-CLIP for 18 h at 37°C. For dissociation, preformed complexes were diluted 10-fold and incubated in 20-l volumes with 100 M unlabeled MAT (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). After neutralization, the complexes were captured on L243-coated microtiter wells at 4°C and biotin complexes were measured with streptavidin-europium as previously described (5).…”

Section: Peptide Dissociation Assayssupporting

confidence: 90%

“…Unilamellar liposomes containing purified DR1 and/or DM were generated as described in Materials and Methods. Samples containing identical quantities of DM and DR1 distributed together or separately into liposomes were incubated for 3 h at pH 5 with 1 M biotin-MAT (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) peptide. After chilling on ice, liposomes were solubilized in 1% NP40 and biotin-MAT-DR1 complexes were quantified by europium fluorescence immunoassay (f).…”

Section: Discussionmentioning

confidence: 99%

“…It was subsequently shown that substoichiometric concentrations of HLA-DO copurify with DM isolated from B cells (15). The function ofDM function in a variety of experimental conditions (15)(16)(17)(18) but it also has been reported to promote the peptide loading and chaperone functions of DM (19,20). The possibility that contaminating HLA-DO was responsible for the enhanced activity of purified DM was ruled out by Busch et al (21), who showed that full-length recombinant DM is much more potent than the soluble protein lacking transmembrane and cytoplasmic domains.…”

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confidence: 99%

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Transmembrane Domain-Mediated Colocalization of HLA-DM and HLA-DR Is Required for Optimal HLA-DM Catalytic Activity

Weber

Dao

Jun

et al. 2001

The Journal of Immunology

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HLA-DM catalyzes peptide loading and exchange reactions by MHC class II molecules. Soluble recombinant DM, lacking transmembrane and cytoplasmic domains, was observed to have 200- to 400-fold less activity compared with the full-length protein in assays measuring DM-catalyzed peptide dissociation from purified HLA-DR1 in detergent solutions. Additional studies with truncated soluble DR1 demonstrated that transmembrane domains in DR1 molecules are also required for optimal activity. The potential requirement for specific interaction between the transmembrane domains of DM and DR was ruled out in experiments with chimeric DR1 molecules containing transmembrane domains from either DM or the unrelated protein CD80. These results suggested that the major role of the transmembrane domains is to facilitate colocalization of DM and DR in detergent micelles. The latter conclusion was further supported by the observation that HLA-DM-catalyzed peptide binding to certain murine class II proteins is increased by reducing the volume of detergent micelles. The importance of membrane colocalization was directly demonstrated in experiments in which DM and DR were reconstituted separately or together into membrane bilayers in unilamellar liposomes. Our findings demonstrate the importance of membrane anchoring in DM activity and underscore the potential importance of membrane localization in regulating peptide exchange by class II molecules.

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Section: Peptide Dissociation Assayssupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Transmembrane Domain-Mediated Colocalization of HLA-DM and HLA-DR Is Required for Optimal HLA-DM Catalytic Activity

Weber

Dao

Jun

et al. 2001

The Journal of Immunology

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“…H2-O −/− B cells outcompeted WT B cells by ∼2-to 5-fold, but did not completely take over the GC niche. This suggests that H2-O-dependent modulation of Ag presentation may be subtle, which is supported by previous studies that examined presentation on the cellular level and found varying effects of H2-O depending on the specific epitope examined (9,(11)(12)(13)(14)(15)25). Nevertheless, small differences in Ag presentation, especially when considering a complex Ag mix containing many individual epitopes, could have a considerable impact on the immune response.…”

Section: Discussionmentioning

confidence: 99%

H2-O, a MHC class II-like protein, sets a threshold for B-cell entry into germinal centers

Draghi¹,

Denzin

2010

Proc. Natl. Acad. Sci. U.S.A.

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Upon antigen (Ag) encounter, B cells require T-cell help to enter the germinal center (GC). They obtain this help by presenting Agderived peptides on MHC class II (MHCII) for recognition by the T-cell receptor (TCR) of CD4 + T cells. Peptides are loaded onto MHCII in endosomal compartments in a process catalyzed by the MHCII-like protein H2-M (HLA-DM in humans). This process is modulated by another MHCII-like protein, H2-O (HLA-DO in humans). H2-O is a biochemical inhibitor of peptide loading onto MHCII; however, on the cellular level, it has been shown to have varying effects on Ag presentation. Thus, the function of H2-O in the adaptive immune response remains unclear. Here, we examine the effect of H2-O expression on the ability of Ag-specific B cells to enter the GC. We show that when Ag specific WT and H2-O −/− B cells are placed in direct competition, H2-O −/− B cells preferentially populate the GC. This advantage is confined to Ag-specific B cells and is due to their superior ability to obtain Ag-specific T-cell help when T-cell help is limiting. Overall, our work shows that H2-O expression reduces the ability of B cells to gain T-cell help and participate in the GC reaction.antigen processing | antigen presentation | H2-M | follicular helper T cells | HLA-DOA ntigen (Ag) processing and presentation on MHCII is central to T cell-dependent Ab-mediated immunity. During an immune response, Ag-specific naïve B cells recognize and internalize Ag via the B-cell receptor (BCR). The Ag is subsequently transported to late endosomes and lysosomes, where it is degraded into peptides, some of which are loaded onto MHC class II (MHCII) (1). These MHCII-peptide complexes are then displayed on the cell surface for recognition by cognate CD4 + T cells. This recognition event allows B cells to obtain T-cell help from a rare population of T cells known as CD4 + follicular helper T cells (T FH ). The interaction between the Ag-specific B cells and T FH cells is essential for B-cell entry into the germinal center (GC) (2).Peptide loading of MHCII is catalyzed by the nonclassical MHCII-like protein H2-M (HLA-DM in humans) (3-5). H2-M, which localizes to endosomes (6), promotes the removal of class IIassociated invariant chain peptides (CLIP) from the peptidebinding groove of MHCII. H2-M also stabilizes empty MHCII molecules and edits the final MHCII-bound peptide repertoire that is displayed at the cell surface to ensure that only long-lived MHCII-peptide complexes are presented (7). Another nonclassical MHCII-like protein, H2-O (HLA-DO in humans), also localizes to endosomes in B cells (8). H2-O forms a complex with H2-M and has been shown to inhibit or modulate the ability of H2-M to catalyze and edit MHCII peptide exchange (9-12). Surprisingly, H2-O-deficient mice exhibit only minor abnormalities in Ag presentation (11, 13).Ag presentation is important for many aspects of immunity, including initiating the GC response. Admission of B cells into the GC is a competitive process that is dependent upon help from Agspecific T F...

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“…Subsequently, mass spectrometry analysis of peptide repertoires has demonstrated that HLA-DM/H-2M functions as a "peptide editor", displacing not only CLIP peptides but poorly-fitting endogenous peptides [104]. A related molecule, HLA-DO/H-2O, serves a similar function [105,106], although its specificity is distinct. Thus, mass spectrometry has played a central role in uncovering the existence of molecules that fine-tune the peptide repertoire displayed by class II MHC molecules.…”

Section: Involvement Of Hla-dm/h-2m In Antigen Presentation By Class mentioning

confidence: 99%

The contributions of mass spectrometry to understanding of immune recognition by T lymphocytes

Engelhard

2007

International Journal of Mass Spectrometry

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Over the last 15 years, the ability of mass spectrometry to analyze complex peptide mixtures and identify individual species has provided unprecedented insights into the repertoire of peptide antigens displayed by MHC molecules and recognized by T lymphocytes. These include: understanding the peptide binding specificity of MHC molecules; understanding of roles of different intracellular components of the antigen processing pathways in determining the peptide display; and identification of a large number of individual peptide antigens associated with infectious diseases, cancer, and transplant rejection that have provided the basis for new immunologically based therapies. This review will summarize the impact that the application of mass spectrometry has had on these advances, with particular attention to the contributions of Professor Donald Hunt and members of his laboratory, and point out the opportunities for future work. Keywordsantigen processing; post-translational modification; peptides; MHC molecules THE NATURE OF ANTIGEN RECOGNITION BY T LYMPHOCYTEST lymphocytes are a branch of the immune system concerned with recognition of antigens that are displayed on the surface of host cells. These antigens are produced through intracellular proteolytic mechanisms that create small peptides, which are then rescued and presented at the cell surface by adaptor proteins called MHC molecules [reviewed in [1-6]. The binding site of each MHC molecule enables it to bind to a wide range of different peptides, and results in the display of a repertoire of such antigens, each recognized by a distinct T lymphocyte. This "antigen processing and presentation" mechanism results in the display of peptides derived from the proteins of pathogens that have infected the cell or been taken up by endocytosis. Their recognition by T lymphocytes results in the development of an immune response, and results in clearance of the pathogen and infected cells from the body. However, antigen processing and presentation pathways operate constitutively on normal cellular proteins as well, resulting in the display of peptide antigens that can be distinguished on tumors and transplanted tissues. Some of these "self-peptides" are also involved in the development of T lymphocytes in the thymus, and their recognition also controls the balance between selftolerance and autoimmune disease. Correspondence: phone: 434-924-2423; fax: 434-924-1221; email: vhe@virginia.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. In most individuals, molecules of each MHC class are expressed from 3 genetic loci that ...

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Altered major histocompatibility complex class II peptide loading in H2-O-deficient mice

Cited by 46 publications

References 37 publications

Transmembrane Domain-Mediated Colocalization of HLA-DM and HLA-DR Is Required for Optimal HLA-DM Catalytic Activity

Transmembrane Domain-Mediated Colocalization of HLA-DM and HLA-DR Is Required for Optimal HLA-DM Catalytic Activity

H2-O, a MHC class II-like protein, sets a threshold for B-cell entry into germinal centers

The contributions of mass spectrometry to understanding of immune recognition by T lymphocytes

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