Cited by 223T-cell and B-cell ImmunologyTransplantation: Methods and OutcomesRenal Transplantation Outcomes and Treatments

T cell Allorecognition Pathways in Solid Organ Transplantation

Open access
Siu, Jacqueline H. Y., Surendrakumar, Veena, Richards, James A., Pettigrew, Gavin J.·2018·Frontiers in Immunology

Abstract

Transplantation is unusual in that T cells can recognize alloantigen by at least two distinct pathways: as intact MHC alloantigen on the surface of donor cells via the direct pathway; and as self-restricted processed alloantigen via the indirect pathway. Direct pathway responses are viewed as strong but short-lived and hence responsible for acute rejection, whereas indirect pathway responses are typically thought to be much longer lasting and mediate the progression of chronic rejection. However, this is based on surprisingly scant experimental evidence, and the recent demonstration that MHC alloantigen can be re-presented intact on recipient dendritic cells – the semi-direct pathway – suggests that the conventional view may be an oversimplification. We review recent advances in our understanding of how the different T cell allorecognition pathways are triggered, consider how this generates effector alloantibody and cytotoxic CD8 T cell alloresponses and assess how these responses contribute to early and late allograft rejection. We further discuss how this knowledge may inform development of cellular and pharmacological therapies that aim to improve transplant outcomes, with focus on the use of induced regulatory T cells with indirect allospecificity and on the development of immunometabolic strategies.

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Crossref · 10.3389/fimmu.2018.02548

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  • The direct pathway provokes the most vigorous immune response by directly representing donor MHC I and MHC II molecules to recipient CD8 and CD4 T cells.

    “The direct pathway provokes the most vigorous immune response by directly representing MHC I and MHC II molecules of the donor’s APCs to recipient CD8 and CD4 T cells, respectively.”

    From Immunogenicity of decellularized extracellular matrix scaffolds: a bottleneck in tissue engineering and regenerative medicine (2023) · cites this paper as [10]

    The Direct pathway section says recipient CD4 and CD8 T cells recognize intact donor APC MHC class II and class I, respectively, and reports a high frequency of responding T cells. It says the pathway was historically considered dominant and is expected to dominate early after transplantation, but does not establish that it provokes the most vigorous response without qualification. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • Activated recipient T cells migrate to the graft site, directly recognize foreign antigens, and participate in acute rejection.

    “Activated recipient T cells migrate to the graft site, directly recognize foreign antigens, and participate in acute rejection.”

    From Immunogenicity of decellularized extracellular matrix scaffolds: a bottleneck in tissue engineering and regenerative medicine (2023) · cites this paper as [10]

    The Direct pathway section says recipient T cells recognize intact donor MHC alloantigens, and Early acute rejection says direct-pathway responses likely dominate early rejection and activated CD8 T cells can target graft cells. Neither passage says activated recipient T cells migrate to the graft site; the migration described in the Direct pathway section is of donor dendritic cells from the graft to host lymphoid tissue. Page numbers are unavailable in our copy. (LLM, conf=0.85)

    Experimental — accuracy not yet measured
  • The indirect pathway invokes a less vigorous response but lasts longer due to the available supply of host APCs and foreign antigens within grafts.

    “Although this pathway invokes a less vigorous response, it lasts longer due to the available supply of host APCs and foreign antigens within the grafts.”

    From Immunogenicity of decellularized extracellular matrix scaffolds: a bottleneck in tissue engineering and regenerative medicine (2023) · cites this paper as [10]

    The figure caption under “Direct pathway” describes recipient APCs processing graft alloantigen, and “Duration of CD4 T cell alloresponses” reports late indirect-pathway activation when processed MHC class I alloantigen remains presented. But that section also says indirect responses to MHC class II allopeptide were as short-lived as direct responses. The paper does not establish that the indirect response is generally less vigorous, so the sentence overgeneralizes both its strength and duration. (LLM, conf=0.85)

    Experimental — accuracy not yet measured
  • The direct pathway response vanishes within a few weeks because of a limited number of donor APCs and their depletion over time.

    “This response vanishes within a few weeks because of a limited number of donor APCs and their depletion over time [10].”

    From Immunogenicity of decellularized extracellular matrix scaffolds: a bottleneck in tissue engineering and regenerative medicine (2023) · cites this paper as [10]

    The “Duration of CD4 T cell alloresponses” section says direct-pathway CD4 responses are generally limited to the first few weeks and that their duration correlates with the lifespan of donor dendritic cells. It does not attribute this to a limited initial number of donor APCs, and it presents the short duration as a finding suggested by studies rather than an absolute disappearance; the same section notes a possible mechanism for later activation. (LLM, conf=0.87)

    Experimental — accuracy not yet measured
  • CD4 T cells regulate both humoral and cytotoxic T cell responses as the main elements of chronic rejection.

    “Moreover, CD4 T cells have a substantial role in regulating both humoral and cytotoxic T cell responses as the main elements of chronic rejection.”

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Research works printed but not linked: 1

  1. [17]Knight SC Iqball S Roberts MS Macatonia S Bedford PA. Transfer of antigen between dendritic cells in the stimulation of primary T cell proliferation. Eur J Immunol. (1998) 28: 1636– 44. 9603470

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Authors
Siu, J. H. Y., Surendrakumar, V., Richards, J. A., & Pettigrew, G. J.
Affiliations
University of Cambridge (GB)
Corresponding author
Pettigrew, Gavin J.
Venue
Frontiers in Immunology
Published
2018-11-05
Volume
9
Pages
2548-2548
ISSN
1664-3224 (ISSN-L)
OpenAlex
W2900406950
Cited by
223
References
153
Citations by year
2026: 9 · 2025: 29 · 2024: 34 · 2023: 48 · 2022: 34 · 2021: 42 · 2020: 25 · 2019: 2
FWCI
1.76
Type
journal article
Language
en
Open access
Locations
  • Frontiers in Immunology (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Apollo (University of Cambridge) (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Apollo (cc-by)
Funders
  • National Institute for Health and Care Research (CL-2015-14-002)
  • British Heart Foundation (FS/12/87/29899)
  • Cambridge Trust
  • Evelyn Trust
  • Gates Cambridge Trust
  • Mason Medical Research Trust
  • NIHR Cambridge Biomedical Research Centre
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › T-cell and B-cell Immunology
  • Health Sciences › Medicine › Surgery › Transplantation: Methods and Outcomes
  • Health Sciences › Medicine › Transplantation › Renal Transplantation Outcomes and Treatments
Keywords
solid organ transplantation, dendritic cell antigen presentation, acute rejection, chronic rejection, alloantibodies, CD8+ cytotoxic T lymphocytes, regulatory T cells, allograft rejection
MeSH terms
Histocompatibility Antigens Class II, Dendritic Cells, Graft Rejection, T-Lymphocytes, Helper-Inducer, Humans, Isoantibodies, Isoantigens, T-Lymphocytes, Cytotoxic, Transplantation, Homologous, Organ Transplantation, T-Lymphocytes, Regulatory

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