A soluble divalent class I MHC/IgG1 fusion protein activates CD8+ T cells in vivo

Circulating platelets interact with leukocytes to modulate host immune and thrombotic responses. In sepsis, platelet-leukocyte interactions are increased, and have been associated with adverse clinical events, including increased platelet-T cell interactions. Sepsis is associated with reduced CD8+ T cell numbers and functional responses, but whether platelets regulate CD8+ T cell responses during sepsis remains unknown. In our current study, we systemically evaluated platelet antigen internalization and presentation through major histocompatibility complex class I (MHC-I) and their effects on antigen specific CD8+ T cells in sepsis in vivo and ex vivo. We discovered that both human and murine platelets internalize and proteolyze exogenous antigens, generating peptides that are loaded onto MHC-I. The expression of platelet MHC-I, but not platelet MHC-II, is significantly increased in human and murine platelets during sepsis and in human megakaryocytes stimulated with agonists generated systemically during sepsis (e.g., IFN-g and LPS). Upregulation of platelet MHC-I during sepsis increases antigen cross-presentation and interactions with CD8+ T cells in an antigen-specific manner. Using a platelet lineage specific MHC-I deficient mouse strain (B2mf/f--Pf4Cre), we demonstrate that platelet MHC-I regulates antigen-specific CD8+ T cell proliferation in vitro, as well as the number and functional responses of CD8+ T cells in vivo during sepsis. Loss of platelet MHC-I reduced sepsis-associated mortality in mice in an antigen specific setting. These data identify a new mechanism by which platelets, through MHC-I, process and cross-present antigens, engage antigen specific CD8+ T cells, and regulate CD8+ T cell number, functional responses, and outcomes during sepsis.

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In vivo priming of two distinct antitumor effector populations: the role of MHC class I expression.

Journal of Experimental Medicine ◽

10.1084/jem.179.4.1215 ◽

1994 ◽

Vol 179 (4) ◽

pp. 1215-1224 ◽

Cited By ~ 132

Author(s):

H I Levitsky ◽

A Lazenby ◽

R J Hayashi ◽

D M Pardoll

Keyword(s):

T Cells ◽

Nk Cells ◽

Mhc Class I ◽

Cd8 T Cells ◽

Tumor Vaccine ◽

Class I ◽

Tumor Challenge ◽

Class I Mhc ◽

Gm Csf

Downregulation of major histocompatibility complex (MHC) class I expression is an important mechanism by which tumors evade classical T cell-dependent immune responses. Therefore, a system was designed to evaluate parameters for active immunization against MHC class I- tumors. Mice were capable of rejecting a MHC class I- tumor challenge after immunization with an irradiated granulocyte/macrophage colony-stimulating factor (GM-CSF) transduced MHC class I- tumor vaccine. This response was critically dependent on CD4+ T cells and natural killer (NK) cells, but minimally on CD8+ T cells. A strong protective response against MHC class I+ variants of the tumor could be elicited when mice were immunized with irradiated MHC class I+ GM-CSF-secreting tumor cells. This response required CD4+ and CD8+ T cells, and in addition, elimination of NK cells resulted in outgrowth of tumors that had lost expression of at least one MHC class I gene. Finally, class I MHC expression on the vaccinating cells inhibited the response generated against a MHC class I- tumor challenge. These results demonstrate that the host is capable of being immunized against a tumor that has lost MHC class I expression and reveal conditions under which distinct effector cells play a role in the systemic antitumor immune response.

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IDENTIFICATION OF A CLASS I MHC-ASSOCIATED PEPTIDE DERIVED FROM THE METH A SARCOMA AND RECOGNIZED BY CD8+ T CELLS

Journal of Immunotherapy ◽

10.1097/00002371-199311000-00062 ◽

1993 ◽

Vol 14 (4) ◽

pp. 369

Author(s):

A Frassanito ◽

J I Mayordomo ◽

W J Storkus ◽

M T Lotze ◽

R DeLeo ◽

...

Keyword(s):

T Cells ◽

Cd8 T Cells ◽

Class I ◽

Class I Mhc ◽

Meth A Sarcoma

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TLR3 essentially promotes protective class I–restricted memory CD8+ T-cell responses to Aspergillus fumigatus in hematopoietic transplanted patients

Blood ◽

10.1182/blood-2011-06-362582 ◽

2012 ◽

Vol 119 (4) ◽

pp. 967-977 ◽

Cited By ~ 79

Author(s):

Agostinho Carvalho ◽

Antonella De Luca ◽

Silvia Bozza ◽

Cristina Cunha ◽

Carmen D'Angelo ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Aspergillus Fumigatus ◽

Cd8 T Cells ◽

T Cell Responses ◽

Cd8 T Cell ◽

Class I ◽

Class I Mhc ◽

Cell Responses ◽

Memory Cd8 T Cell

Abstract Aspergillus fumigatus is a model fungal pathogen and a common cause of severe infections and diseases. CD8+ T cells are present in the human and murine T-cell repertoire to the fungus. However, CD8+ T-cell function in infection and the molecular mechanisms that control their priming and differentiation into effector and memory cells in vivo remain elusive. In the present study, we report that both CD4+ and CD8+ T cells mediate protective memory responses to the fungus contingent on the nature of the fungal vaccine. Mechanistically, class I MHC-restricted, CD8+ memory T cells were activated through TLR3 sensing of fungal RNA by cross-presenting dendritic cells. Genetic deficiency of TLR3 was associated with susceptibility to aspergillosis and concomitant failure to activate memory-protective CD8+ T cells both in mice and in patients receiving stem-cell transplantations. Therefore, TLR3 essentially promotes antifungal memory CD8+ T-cell responses and its deficiency is a novel susceptibility factor for aspergillosis in high-risk patients.

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Self–class I MHC molecules support survival of naive CD8 T cells, but depress their functional sensitivity through regulation of CD8 expression levels

Journal of Experimental Medicine ◽

10.1084/jem.20082553 ◽

2009 ◽

Vol 206 (10) ◽

pp. 2253-2269 ◽

Cited By ~ 53

Author(s):

Kensuke Takada ◽

Stephen C. Jameson

Keyword(s):

T Cells ◽

T Cell ◽

Cell Survival ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

Class I ◽

Class I Mhc ◽

Mhc Molecules ◽

T Cell Survival ◽

And Function

Previous studies have suggested that naive CD8 T cells require self-peptide–major histocompatability complex (MHC) complexes for maintenance. However, interpretation of such studies is complicated because of the involvement of lymphopenic animals, as lymphopenia drastically alters naive T cell homeostasis and function. In this study, we explored naive CD8 T cell survival and function in nonlymphopenic conditions by using bone marrow chimeric donors and hosts in which class I MHC expression is absent or limited to radiosensitive versus radioresistant cells. We found that long-term survival of naive CD8 T cells (but not CD4 T cells) was impaired in the absence of class I MHC. However, distinct from this effect, class I MHC deprivation also enhanced naive CD8 T cell responsiveness to low-affinity (but not high-affinity) peptide–MHC ligands. We found that this improved sensitivity was a consequence of up-regulated CD8 levels, which was mediated through a transcriptional mechanism. Hence, our data suggest that, in a nonlymphopenic setting, self-class I MHC molecules support CD8 T cell survival, but that these interactions also attenuate naive T cell sensitivity by dynamic tuning of CD8 levels.

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Efficient Targeting of Protein Antigen to the Dendritic Cell Receptor DEC-205 in the Steady State Leads to Antigen Presentation on Major Histocompatibility Complex Class I Products and Peripheral CD8+ T Cell Tolerance

Journal of Experimental Medicine ◽

10.1084/jem.20021598 ◽

2002 ◽

Vol 196 (12) ◽

pp. 1627-1638 ◽

Cited By ~ 921

Author(s):

Laura Bonifaz ◽

David Bonnyay ◽

Karsten Mahnke ◽

Miguel Rivera ◽

Michel C. Nussenzweig ◽

...

Keyword(s):

T Cells ◽

Major Histocompatibility Complex ◽

Steady State ◽

T Cell ◽

Mhc Class I ◽

Cd8 T Cells ◽

Class I ◽

Histocompatibility Complex ◽

Dc Maturation

To identify endocytic receptors that allow dendritic cells (DCs) to capture and present antigens on major histocompatibility complex (MHC) class I products in vivo, we evaluated DEC-205, which is abundant on DCs in lymphoid tissues. Ovalbumin (OVA) protein, when chemically coupled to monoclonal αDEC-205 antibody, was presented by CD11c+ lymph node DCs, but not by CD11c− cells, to OVA-specific, CD4+ and CD8+ T cells. Receptor-mediated presentation was at least 400 times more efficient than unconjugated OVA and, for MHC class I, the DCs had to express transporter of antigenic peptides (TAP) transporters. When αDEC-205:OVA was injected subcutaneously, OVA protein was identified over a 4–48 h period in DCs, primarily in the lymph nodes draining the injection site. In vivo, the OVA protein was selectively presented by DCs to TCR transgenic CD8+ cells, again at least 400 times more effectively than soluble OVA and in a TAP-dependent fashion. Targeting of αDEC-205:OVA to DCs in the steady state initially induced 4–7 cycles of T cell division, but the T cells were then deleted and the mice became specifically unresponsive to rechallenge with OVA in complete Freund's adjuvant. In contrast, simultaneous delivery of a DC maturation stimulus via CD40, together with αDEC-205:OVA, induced strong immunity. The CD8+ T cells responding in the presence of agonistic αCD40 antibody produced large amounts of interleukin 2 and interferon γ, acquired cytolytic function in vivo, emigrated in large numbers to the lung, and responded vigorously to OVA rechallenge. Therefore, DEC-205 provides an efficient receptor-based mechanism for DCs to process proteins for MHC class I presentation in vivo, leading to tolerance in the steady state and immunity after DC maturation.

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Immunotherapy of a murine tumor with interleukin 2. Increased sensitivity after MHC class I gene transfection.

Journal of Experimental Medicine ◽

10.1084/jem.166.6.1716 ◽

1987 ◽

Vol 166 (6) ◽

pp. 1716-1733 ◽

Cited By ~ 61

Author(s):

J S Weber ◽

G Jay ◽

K Tanaka ◽

S A Rosenberg

Keyword(s):

T Cells ◽

Mhc Class I ◽

Interleukin 2 ◽

Class I ◽

High Dose ◽

Class I Mhc ◽

High Doses ◽

I Gene

We have shown that two weakly immunogenic MCA sarcomas developed in our laboratory that are sensitive to high-dose IL-2 immunotherapy express class I MHC in vivo and in vitro. Two nonimmunogenic MCA sarcomas are relatively insensitive to IL-2 therapy and express minimal or no class I MHC molecules in vivo and in vitro. To study the role of MHC in the therapy of tumors with IL-2, a class I-deficient murine melanoma, B16BL6, was transfected with the Kb class I gene. Expression of class I MHC rendered B16BL6 advanced pulmonary macrometastases sensitive to IL-2 immunotherapy. 3-d micrometastases of CL8-2, a class I transfected clone of B16BL6, were significantly more sensitive to IL-2 therapy than a control nontransfected line. Expression of Iak, a class II MHC molecule, had no effect on IL-2 therapy of transfectant pulmonary micrometastases in F1 mice. By using lymphocyte subset depletion with mAbs directed against Lyt-2, therapy of class I transfectant macrometastases with high-dose IL-2 was shown to involve an Lyt-2 cell. In contrast, regression of micrometastases treated with low-dose IL-2 involved Lyt-2+ cells, but regression mediated by high doses of IL-2 did not. We hypothesize that both LAK and Lyt-2+ T cells effect IL-2-mediated elimination of micrometastases, but only Lyt-2+ T cells are involved in macrometastatic regression. Low doses of IL-2 stimulate Lyt-2+ cells to eliminate class I-expressing micrometastases, but high doses of IL-2 can recruit LAK cells to mediate regression of micrometastases independent of class I expression. Only high-dose IL-2, mediating its effect predominantly via Lyt-2+ cells, is capable of impacting on MHC class I-expressing macrometastases. Macrometastases devoid of class I MHC antigens appear to be resistant to IL-2 therapy.

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IFN-α enhances cross-presentation in human dendritic cells by modulating antigen survival, endocytic routing, and processing

Blood ◽

10.1182/blood-2011-06-363564 ◽

2012 ◽

Vol 119 (6) ◽

pp. 1407-1417 ◽

Cited By ~ 87

Author(s):

Francesca Spadaro ◽

Caterina Lapenta ◽

Simona Donati ◽

Laura Abalsamo ◽

Vincenzo Barnaba ◽

...

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Mhc Class I ◽

Cd8 T Cells ◽

Tumor Development ◽

Class I ◽

Cross Presentation ◽

The Cross ◽

Human Dendritic Cells

Abstract Cross-presentation allows antigen-presenting cells to present exogenous antigens to CD8+ T cells, playing an essential role in controlling infections and tumor development. IFN-α induces the rapid differentiation of human mono-cytes into dendritic cells, known as IFN-DCs, highly efficient in mediating cross-presentation, as well as the cross-priming of CD8+ T cells. Here, we have investigated the mechanisms underlying the cross-presentation ability of IFN-DCs by studying the intracellular sorting of soluble ovalbumin and nonstructural-3 protein of hepatitis C virus. Our results demonstrate that, independently from the route and mechanism of antigen entry, IFN-DCs are extraordinarily competent in preserving internalized proteins from early degradation and in routing antigens toward the MHC class-I processing pathway, allowing long-lasting, cross-priming capacity. In IFN-DCs, both early and recycling endosomes function as key compartments for the storage of both antigens and MHC-class I molecules and for proteasome- and transporter-associated with Ag processing–dependent auxiliary cross-presentation pathways. Because IFN-DCs closely resemble human DCs naturally occurring in vivo in response to infections and other danger signals, these findings may have important implications for the design of vaccination strategies in neoplastic or chronic infectious diseases.

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Constitutive versus Activation-dependent Cross-Presentation of Immune Complexes by CD8+ and CD8− Dendritic Cells In Vivo

Journal of Experimental Medicine ◽

10.1084/jem.20020295 ◽

2002 ◽

Vol 196 (6) ◽

pp. 817-827 ◽

Cited By ~ 230

Author(s):

Joke M.M. den Haan ◽

Michael J. Bevan

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Mhc Class I ◽

Cd8 T Cells ◽

Immune Complexes ◽

Class I ◽

Cross Presentation ◽

Deficient Mice ◽

Mhc Class I Molecules

Murine splenic dendritic cells (DCs) can be divided into two subsets based on CD8α expression, but the specific role of each subset in stimulation of T cells is largely unknown. An important function of DCs is the ability to take up exogenous antigens and cross-present them in the context of major histocompatibility complex (MHC) class I molecules to CD8+ T cells. We previously demonstrated that, when cell-associated ovalbumin (OVA) is injected into mice, only the CD8+ DC subset cross-presents OVA in the context of MHC class I. In contrast to this selectivity with cell-associated antigen, we show here that both DC subsets isolated from mice injected with OVA/anti-OVA immune complexes (OVA-IC) cross-present OVA to CD8+ T cells. The use of immunoglobulin G Fc receptor (FcγR) common γ-chain–deficient mice revealed that the cross-presentation by CD8− DCs depended on the expression of γ-chain–containing activating FcγRs, whereas cross-presentation by CD8+ DCs was not reduced in γ-chain–deficient mice. These results suggest that although CD8+ DCs constitutively cross-present exogenous antigens in the context of MHC class I molecules, CD8− DCs only do so after activation, such as via ligation of FcγRs. Cross-presentation of immune complexes may play an important role in autoimmune diseases and the therapeutic effect of antitumor antibodies.

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