A study of KIR binding to HLA-C
Author(s)
Fadda, Lena
Type
Thesis
Abstract
NK cell cytotoxic functions are under the control of a large array of inhibitory and
activating cell surface receptors. One class of inhibitory receptors are the MHC class I
specific Killer Immunoglobulin-like Receptors (KIRs). Different KIRs recognise
different groups of HLA molecules. KIR2DL2 and KIR2DL3 segregate as alleles of
the same locus and recognise the same HLA-C group 1 allotypes (HLA-C1). Loss of
an inhibitory signal is one mechanism by which NK cells might recognise an infected
cell.
KIR-Ig proteins were generated to study the direct binding of KIR2DL2 and
KIR2DL3 to HLA-C1: peptide complexes. The TAP-deficient T2 cell line expresses
HLA-Cw*0102 (HLA-C1) and can be loaded with exogenous peptide to generate
stable peptide: MHC class I complexes. Using an endogenous peptide, VAPWNSLSL
as a template, known to bind to HLA-Cw*0102, a panel of seven peptides with
mutations at residues 7 and 8 was studied to assess KIR binding. A peptide hierarchy
was defined for KIR2DL2 and KIR2DL3 binding; peptides that mediated strong,
intermediate or weak recognition of KIR to HLA-Cw*0102 were identified. A similar
peptide hierarchy was observed to inhibit NK cells in CD107a assays. We showed
that KIR2DL3 binds more strongly to HLA-Cw*0102: peptide than KIR2DL2,
although in CD107a assays, KIR2DL2+ NK cells were not more inhibited than
KIR2DL3+ NK cells. The peptide hierarchy was used to generate in vitro peptide
repertoires containing strong and weak KIR-binding peptides. We observed that the
weak KIR-binding peptide VAPWNSDAL can abrogate the inhibition of NK cells by
the strong KIR-binding peptide VAPWNSFAL, despite levels of HLA-C remaining
constant. This loss of NK cell inhibition in the presence of VAPWNSDAL occurred
at more than 1 log higher concentration of VAPWNSFAL than in the absence of
VAPWNSDAL. These data indicate that changes in peptide repertoire are
significantly more efficient than class I down-regulation at releasing NK cells from
inhibition.
activating cell surface receptors. One class of inhibitory receptors are the MHC class I
specific Killer Immunoglobulin-like Receptors (KIRs). Different KIRs recognise
different groups of HLA molecules. KIR2DL2 and KIR2DL3 segregate as alleles of
the same locus and recognise the same HLA-C group 1 allotypes (HLA-C1). Loss of
an inhibitory signal is one mechanism by which NK cells might recognise an infected
cell.
KIR-Ig proteins were generated to study the direct binding of KIR2DL2 and
KIR2DL3 to HLA-C1: peptide complexes. The TAP-deficient T2 cell line expresses
HLA-Cw*0102 (HLA-C1) and can be loaded with exogenous peptide to generate
stable peptide: MHC class I complexes. Using an endogenous peptide, VAPWNSLSL
as a template, known to bind to HLA-Cw*0102, a panel of seven peptides with
mutations at residues 7 and 8 was studied to assess KIR binding. A peptide hierarchy
was defined for KIR2DL2 and KIR2DL3 binding; peptides that mediated strong,
intermediate or weak recognition of KIR to HLA-Cw*0102 were identified. A similar
peptide hierarchy was observed to inhibit NK cells in CD107a assays. We showed
that KIR2DL3 binds more strongly to HLA-Cw*0102: peptide than KIR2DL2,
although in CD107a assays, KIR2DL2+ NK cells were not more inhibited than
KIR2DL3+ NK cells. The peptide hierarchy was used to generate in vitro peptide
repertoires containing strong and weak KIR-binding peptides. We observed that the
weak KIR-binding peptide VAPWNSDAL can abrogate the inhibition of NK cells by
the strong KIR-binding peptide VAPWNSFAL, despite levels of HLA-C remaining
constant. This loss of NK cell inhibition in the presence of VAPWNSDAL occurred
at more than 1 log higher concentration of VAPWNSFAL than in the absence of
VAPWNSDAL. These data indicate that changes in peptide repertoire are
significantly more efficient than class I down-regulation at releasing NK cells from
inhibition.
Date Issued
2009
Date Awarded
2009-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Khakoo, Salim
Creator
Fadda, Lena
Publisher Department
Hepatology
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)