Biology subjects

McMichael, A. J.

Publications and source records attributed to McMichael, A. J..

7 recordsLinked to original sources

bioRxiv2024

A high affinity monoclonal antibody against HLA-E-VL9 enhances natural killer cell anti-tumor killing

A major natural killer (NK) cell and CD8+ T cell checkpoint is mediated by the inhibitory receptor NKG2A/CD94 and its ligand, HLA-E complexed with 9 amino acid HLA-Ia leader sequence-derived peptides termed VL9 (HLA-E-VL9). Here, we used structure-based design and high throughput library screening to generate antibodies that block NKG2A/CD94 interactions, resulting in direct NK and CD8+ T cell cytotoxicity, and trigger NK cell antibody-dependent cellular cytotoxicity (ADCC). Anti-HLA-E-VL9 antibodies limited HLA-E-VL9+ tumor growth in mice, demonstrating checkpoint inhibition activity in vivo. HLA-E-VL9 was found to be expressed on HIV-infected cells, and its engagement by HLA-E-VL9 antibodies eliminated infected cells by NK-mediated ADCC. HLA-E-VL9 antibodies also enhanced the killing of HIV-infected cells by NKG2A/CD94+ CD8+ T cells targeting a novel HLA-E binding HIV Rev-derived epitope. Therefore, anti-HLA-E-VL9 antibodies represent a novel approach to eliminate pathogenic target cells by enhancing NK and CD8+ T cell function and promoting ADCC.

immunology↗

bioRxiv2022

An unbiased characterization of the HLA-E and CD94/NKG2x peptide repertoire reveals peptide ligands that skew NK cell activation

HLA-E is a non-classical class I MHC protein involved in innate and adaptive immune recognition. While recent studies have shown HLA-E can present diverse peptides to NK cells and T cells, the HLA-E and NK receptor peptide repertoire has remained poorly defined, with only a limited number of peptide ligands identified. Here we screen a yeast-displayed peptide library in the context of HLA-E to identify 500 high-confidence unique peptides that bind both HLA-E and CD94/NKG2A or CD94/NKG2C. Utilizing the sequences identified via yeast display selections, we train prediction algorithms and identify human and cytomegalovirus (CMV) proteome-derived, HLA-E-presented peptides capable of binding and signaling through both CD94/NKG2A and CD94/NKG2C. In addition, we identify peptides which selectively activate NKG2C+ NK cells. Taken together, characterization of the HLA-E-binding peptide repertoire and identification of NK activity-modulating peptides present opportunities for studies of NK cell regulation in health and disease, in addition to vaccine and therapeutic design.

immunology↗

bioRxiv2022

Mapping the epitopes of the Human Leukocyte Antigen E antibodies 3D12 and 4D12

The commonly used commercially available antibodies 3D12 and 4D12 recognise the human leukocyte antigen E (HLA-E) protein. 3D12 is known to exhibit minimal cross-reactivity with classical HLA-Ia allotypes and we confirm that this is also the case for 4D12. These antibodies bind different epitopes on HLA-E, and differ in their ability to recognise alleles of the major histocompatibility complex E (MHC-E) proteins of rhesus and cynomolgus macaques. Using hybrids of different MHC-E alleles, we have mapped the regions that are critical for the binding of these two antibodies. 3D12 recognises a region on the alpha 3 domain that is unique to HLA-E, on the opposite side to that bound by {beta}2-microglobulin, while 4D12 recognises the start of the alpha 2 domain, adjacent to the C terminus of the presented peptide. Knowledge of the binding sites of these two antibodies will facilitate selection of the best antibody for a given application, and inform interpretation of the resulting data.

immunology↗

bioRxiv2020

IgM Natural Antibodies Bind HLA-E-Leader Peptide Complexes and Modulate NK Cell Cytotoxicity

HLA-E is a non-classical class Ib molecule that has limited polymorphism and binds HLA class Ia leader peptides (VL9). HLA-E-VL9 complexes interact with the natural killer (NK) cell receptors NKG2A-C/CD94 and regulate NK cell-mediated cytotoxicity. Here we isolated a murine IgM antibody 3H4, that specifically recognized HLA-E-VL9 bound complexes and enhanced killing of HLA-E-VL9-expressing cells by an NKG2A+ NK cell line. Structural analysis revealed how 3H4 prevents CD94/NKG2A docking on HLA-E-VL9 by binding with an overlapping footprint. Upon in vitro maturation, an affinity-optimized 3H4 IgG showed enhanced NK killing of HLA-E-VL9-expressing cells. Remarkably, HLA-E-VL9-specific IgM autoantibodies with similar specificity and functions to 3H4 were subsequently isolated from naive B cells of cytomegalovirus (CMV)-negative, healthy male human donors. Thus, a repertoire of germline low affinity HLA-E-VL9-reactive antibodies are present in both naive human and murine B cell repertoires. These antibodies can enhance NK cell cytotoxicity and therefore have potential for therapeutic modulation of NK cell function.

immunology↗

bioRxiv2020

HLA-E restricted, HIV-1 suppressing, Gag specific CD8+ T cells offer universal vaccine opportunities

Human leukocyte antigen-E (HLA-E) normally presents a HLA class Ia signal peptide to the NKG2A/C-CD94 regulatory receptors on natural killer (NK) cells and T cell subsets. Rhesus macaques immunized with a cytomegalovirus vectored simian immunodeficiency virus (SIV) vaccine, generated Mamu-E (HLA-E homolog) restricted T cell responses that mediated post-challenge SIV replication arrest in >50% of animals. However, human immunodeficiency virus type 1 (HIV-1) specific HLA-E restricted T cells have not been observed in HIV-1-infected individuals. Here we primed HLA-E restricted HIV-1 specific CD8+ T cells in vitro. These T cell clones, and allogeneic CD8+ T cells transduced with their T cell receptors, suppressed HIV-1 replication in CD4+ T cells in vitro. Vaccine induction of efficacious HLA-E restricted HIV-1 specific T cells should therefore be possible. One Sentence SummaryCD8+ T cells that recognize a Gag peptide presented by HLA-E suppress HIV-1 replication in vitro.

immunology↗

bioRxiv2020

Detailed and atypical HLA-E peptide binding motifs revealed by a novel peptide exchange binding assay

Diverse SIV epitopes that bind the rhesus homologue of HLA-E, Mamu-E, have recently been identified in SIV-vaccine studies using a recombinant Rhesus cytomegalovirus (RhCMV 68-1) vector, where unprecedented protection against SIV challenge was achieved. Additionally, several Mycobacterial peptides identified both algorithmically and following elution from infected cells, are presented to CD8+ T cells by HLA-E in humans. Yet, a comparative and comprehensive analysis of relative HLA-E peptide binding strength via a reliable, high throughput in vitro assay is currently lacking. To address this we developed and optimised a novel, highly sensitive peptide exchange ELISA-based assay that relatively quantitates peptide binding to HLA-E. Using this approach we screened multiple peptides, including peptide panels derived from HIV, SIV and Mtb predicted to bind HLA-E. Our results indicate that although HLA-E preferentially accommodates canonical MHC class I leader peptides, many non-canonical, sequence diverse, pathogen-derived peptides also bind HLA-E, albeit generally with lower relative binding strength. Additionally, our screens demonstrate that the majority of peptides tested, including some key Mtb and SIV epitopes which have been shown to elicit strong Mamu-E-restricted T cell responses, either bind HLA-E extremely weakly or give signals that are indistinguishable from the negative, peptide-free controls.

immunology↗

bioRxiv2019

CD4+ T follicular helper (Tfh) cells in human tonsil and blood are clonally convergent, but divergent from non-Tfh CD4+ cells

T follicular helper (Tfh) cells are fundamental for B cell selection and antibody maturation in germinal centers. Circulating Tfh (cTfh) cells constitute a minor proportion of the CD4+ T cells in peripheral blood, but their clonotypic relationship to Tfh populations resident in lymph nodes and the extent to which they differ from non-Tfh CD4+ cells has been unclear. Using donor-matched blood and tonsil samples we investigated T cell receptor (TCR) sharing between tonsillar Tfh cells and peripheral Tfh and non-Tfh cell populations. TCR transcript sequencing revealed considerable clonal overlap between peripheral and tonsillar Tfh cell subsets as well as a clear distinction between Tfh and non-Tfh cells. Furthermore, influenza-specific cTfh cell clones derived from blood could be found in the repertoire of tonsillar Tfh cells. Therefore, human blood samples can be used to gain insight into the specificity of Tfh responses occurring in lymphoid tissues, provided cTfh subsets are studied.

immunology↗