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The peptide binding specificity of the inhibitory and activating KIR2D receptors

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Title: The peptide binding specificity of the inhibitory and activating KIR2D receptors
Authors: Cassidy, Sorcha
Item Type: Thesis or dissertation
Abstract: Human natural killer (NK) cells play an invaluable role in the first line of innate immune defence against viral infection and cancer. They are the main sub-group of lymphocytes with predominant expression of polymorphic KIR (Killer-immunoglobulin-like-receptors), which allows them to engage with their MHC Class I ligands. Past immunogenetic analysis has shown that possession of KIR2DL3 may confer an advantage in eliminating acute Hepatitis C virus (HCV) infection. This contrasts with those possessing KIR2DL2 who were found not to spontaneously resolve infection. Previous work has shown that different variants of an endogenous peptide VAPWNSLSL (VAP) can modulate the KIR2DL2/3-HLA-C1 interaction. Here we have analysed the peptide repertoire in the context of the inhibitory KIR2DL3, KIR2DL2 receptors and the activating KIR2DS2 receptor. We firstly investigated any differences in KIR2DL3+ or KIR2DL2+ NK cell reactivity in response to mixes containing VAP peptide derivatives with the aim that these peptide mixes would be representative of the diverse peptide repertoire on a cell. Overall, we found that NK cells from KIR2DL3 homozygous donors were more sensitive to changes in the peptide content of MHC class I than those from KIR2DL2 homozygous donors. As HCV is an infection with a well-recognised association of outcome with specific KIR, we also sought to determine whether HCV peptides could modulate KIR2DL2/3+ NK cell reactivity. We investigated the ability of the panel of HCV peptides to influence NK cell reactivity firstly via KIR2DL2 or KIR2DL3. The majority of HCV peptides were weak binders for HLA-Cw*0102 and/or non-inhibitory. We found that a HCV peptide (HCV NS31254-1263 LNPSVAATL) was able to promote weak binding of the KIR2DS2 to the HLA-Cw*0102 allele and subsequently affect KIR2DS2+ NK cell reactivity. Here we report that LNP can effectively promote binding of KIR2DS2 tetramers and affect the functionality of KIR2DS2+ NK cell clones. Thus, we propose that the HCV-derived peptide LNP can act as an agonistic peptide on NK cell activation through KIR2DS2.
Content Version: Open Access
Issue Date: Nov-2014
Date Awarded: May-2015
URI: http://hdl.handle.net/10044/1/27222
DOI: https://doi.org/10.25560/27222
Supervisor: Purbhoo, Marco
Khakoo, Salim
Sponsor/Funder: Wellcome Trust (London, England)
Department: Department of Medicine
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Medicine PhD theses



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