Influence of HLA-C environment on the spontaneous clearance of hepatitis C in European HIV-HCV co-infected individuals.

Natural killer (NK) cell functions are regulated by diverse inhibitory and activating receptors, including killer cell immunoglobulin-like receptors (KIR), which interact with human leukocyte antigen (HLA) class I molecules. Some KIR/HLA genetic combinations were reported associated with spontaneous clearance (SC) of hepatitis C virus (HCV) but with discordant results, possibly reflecting KIR and/or HLA gene polymorphism according to populations. KIR/HLA genetic combinations associated with both an exhaustive NK and T cell repertoire were investigated in a cohort of HIV-HCV co-infected individuals with either SC (n = 68) or chronic infection (CI, n = 163) compared to uninfected blood donors [controls (Ctrl), n = 100]. Multivariate analysis showed that the HLA C2C2 environment was associated with SC only in European HIV-HCV co-infected individuals [odds ratio (OR) = 4·30, 95% confidence interval = 1·57-12·25, P = 0·005]. KIR2D+ NK cell repertoire and potential of degranulation of KIR2DL1/S1+ NK cells were similar in the SC European cohort compared to uninfected individuals. In contrast, decreased frequencies of KIR2DS1+ and KIR2DL2+ NK cells were detected in the CI group of Europeans compared to SC and a decreased frequency of KIR2DL1/S1+ NK cells compared to controls. Regarding T cells, higher frequencies of DNAX accessory molecule-1 (DNAM-1)+ and CD57+ T cells were observed in SC in comparison to controls. Interestingly, SC subjects emphasized increased frequencies of KIR2DL2/L3/S2+ T cells compared to CI subjects. Our study underlines that the C2 environment may activate efficient KIR2DL1+ NK cells in a viral context and maintain a KIR2DL2/L3/S2+ mature T cell response in the absence of KIR2DL2 engagement with its cognate ligands in SC group of HCV-HIV co-infected European patients.

KIR Polymorphism Modulates the Size of the Adaptive NK Cell Pool in Human Cytomegalovirus-Infected Individuals.

Acute infection with human CMV (HCMV) induces the development of adaptive NKG2C+ NK cells. In some cases, large expansions of this subset, characterized by coexpression of HLA-C-specific KIR, are stably maintained during the life-long latent phase of infection. The factors that control these unusual expansions in vivo are currently unknown. In this study, the role of KIR polymorphism and expression in this process was analyzed. It is shown that strong NKG2C+ NK cell expansions are dominated by single KIR clones, whereas moderate expansions are frequently polyclonal (p < 0.0001). Importantly, the choice of KIR was not arbitrary but biased toward usage of HLA-C-specific KIR encoded by the centromeric part of group A (cenA) haplotypes. Consideration of KIR allelic variation and gene copy number revealed that the cenA effect was predominantly due to the HLA-C2-specific KIR2DL1 receptor; presence of KIR2DL1 on NKG2C+ NK cells led to significantly larger clonal expansions than the cenB-encoded KIR2DL2 (p = 0.002). Expansion of NKG2C+KIR2DL1+ NK cells was always accompanied by the cognate ligand HLA-C2. Moreover, in these donors the frequency of NKG2C+ NK cells correlated with the concentration of anti-HCMV IgG (r = 0.62, p = 0.008), suggesting direct relevance of NKG2C+KIR2DL1+ NK cells for virus control. Altogether, the study suggests that the homeostasis of NKG2C+ NK cells in HCMV infection is at least partly controlled by coexpression of cognate inhibitory KIR. In particular, the strong interaction of KIR2DL1 and HLA-C2 ligands seems to promote large and stable expansion of adaptive NK cells in HCMV infection.

Resurrecting KIR2DP1: A Key Intermediate in the Evolution of Human Inhibitory NK Cell Receptors That Recognize HLA-C.

KIR2DP1 is an inactive member of the human lineage III KIR family, which includes all HLA-C-specific receptor genes. The lethal, and only, defect in KIR2DP1 is a nucleotide deletion in codon 88. Fixed in modern humans, the deletion is also in archaic human genomes. KIR2DP1 is polymorphic, with dimorphism at specificity-determining position 44. By repairing the deletion, we resurrected 11 alleles of KIR2DP1F , the functional antecedent of KIR2DP1 We demonstrate how K44-KIR2DP1F with lysine 44 recognized C1+HLA-C, whereas T44-KIR2DP1F recognized C2+HLA-C. Dimorphisms at 12 other KIR2DP1F residues modulate receptor avidity or signaling. KIR2DP1 and KIR2DL1 are neighbors in the centromeric KIR region and are in tight linkage disequilibrium. Like KIR2DL1, KIR2DP1 contributed to CenA and CenB KIR haplotype differences. Encoded on CenA, C1-specific K44-KIR2DP1F were stronger receptors than the attenuated C2-specific T44-KIR2DP1F encoded on CenB The last common ancestor of humans and chimpanzees had diverse lineage III KIR that passed on to chimpanzees but not to humans. Early humans inherited activating KIR2DS4 and an inhibitory lineage III KIR, likely encoding a C1-specific receptor. The latter spawned the modern family of HLA-C receptors. KIR2DP1F has properties consistent with KIR2DP1F having been the founder gene. The first KIR2DP1F alleles encoded K44-C1 receptors; subsequently KIR2DP1F alleles encoding T44-C2 receptors evolved. The emergence of dedicated KIR2DL2/3 and KIR2DL1 genes encoding C1 and C2 receptors, respectively, could have led to obsolescence of KIR2DP1F Alternatively, pathogen subversion caused its demise. Preservation of KIR2DP1F functional polymorphism was a side effect of fixation of the deletion in KIR2DP1F by micro gene conversion.

NK Cell Proliferation Induced by IL-15 Transpresentation Is Negatively Regulated by Inhibitory Receptors.

IL-15 bound to the IL-15Rα-chain (IL-15Rα) is presented in trans to cells bearing the IL-2Rß-chain and common γ-chain. As IL-15 transpresentation occurs in the context of cell-to-cell contacts, it has the potential for regulation by and of other receptor-ligand interactions. In this study, human NK cells were tested for the sensitivity of IL-15 transpresentation to inhibitory receptors. Human cells expressing HLA class I ligands for inhibitory receptors KIR2DL1, KIR2DL2/3, or CD94-NKG2A were transfected with IL-15Rα. Proliferation of primary NK cells in response to transpresented IL-15 was reduced by engagement of either KIR2DL1 or KIR2DL2/3 by cognate HLA-C ligands. Inhibitory KIR-HLA-C interactions did not reduce the proliferation induced by soluble IL-15. Therefore, transpresentation of IL-15 is subject to downregulation by MHC class I-specific inhibitory receptors. Similarly, proliferation of the NKG2A(+) cell line NKL induced by IL-15 transpresentation was inhibited by HLA-E. Coengagement of inhibitory receptors, either KIR2DL1 or CD94-NKG2A, did not inhibit phosphorylation of Stat5 but inhibited selectively phosphorylation of Akt and S6 ribosomal protein. IL-15Rα was not excluded from, but was evenly distributed across, inhibitory synapses. These findings demonstrate a novel mechanism to attenuate IL-15-dependent NK cell proliferation and suggest that inhibitory NK cell receptors contribute to NK cell homeostasis.

Polymorphic HLA-C Receptors Balance the Functional Characteristics of KIR Haplotypes.

The human killer cell Ig-like receptor (KIR) locus comprises two groups of KIR haplotypes, termed A and B. These are present in all human populations but with different relative frequencies, suggesting they have different functional properties that underlie their balancing selection. We studied the genomic organization and functional properties of the alleles of the inhibitory and activating HLA-C receptors encoded by KIR haplotypes. Because every HLA-C allotype functions as a ligand for KIR, the interactions between KIR and HLA-C dominate the HLA class I-mediated regulation of human NK cells. The C2 epitope is recognized by inhibitory KIR2DL1 and activating KIR2DS1, whereas the C1 epitope is recognized by inhibitory KIR2DL2 and KIR2DL3. This study shows that the KIR2DL1, KIR2DS1, and KIR2DL2/3 alleles form distinctive phylogenetic clades that associate with specific KIR haplotypes. KIR A haplotypes are characterized by KIR2DL1 alleles that encode strong inhibitory C2 receptors and KIR2DL3 alleles encoding weak inhibitory C1 receptors. In striking contrast, KIR B haplotypes are characterized by KIR2DL1 alleles that encode weak inhibitory C2 receptors and KIR2DL2 alleles encoding strong inhibitory C1 receptors. The wide-ranging properties of KIR allotypes arise from substitutions throughout the KIR molecule. Such substitutions can influence cell surface expression, as well as the avidity and specificity for HLA-C ligands. Consistent with the crucial role of inhibitory HLA-C receptors in self-recognition, as well as NK cell education and response, most KIR haplotypes have both a functional C1 and C2 receptor, despite the considerable variation that occurs in ligand recognition and surface expression.

HIV-1 adaptation to NK-cell-mediated immune pressure.

Natural killer (NK) cells have an important role in the control of viral infections, recognizing virally infected cells through a variety of activating and inhibitory receptors. Epidemiological and functional studies have recently suggested that NK cells can also contribute to the control of HIV-1 infection through recognition of virally infected cells by both activating and inhibitory killer immunoglobulin-like receptors (KIRs). However, it remains unknown whether NK cells can directly mediate antiviral immune pressure in vivo in humans. Here we describe KIR-associated amino-acid polymorphisms in the HIV-1 sequence of chronically infected individuals, on a population level. We show that these KIR-associated HIV-1 sequence polymorphisms can enhance the binding of inhibitory KIRs to HIV-1-infected CD4(+) T cells, and reduce the antiviral activity of KIR-positive NK cells. These data demonstrate that KIR-positive NK cells can place immunological pressure on HIV-1, and that the virus can evade such NK-cell-mediated immune pressure by selecting for sequence polymorphisms, as was previously described for virus-specific T cells and neutralizing antibodies. NK cells might therefore have a previously underappreciated role in contributing to viral evolution.

Peptide selectivity discriminates NK cells from KIR2DL2- and KIR2DL3-positive individuals.

Natural killer cells are controlled by peptide selective inhibitory receptors for MHC class I, including the killer cell immunoglobulin-like receptors (KIRs). Despite having similar ligands, KIR2DL2 and KIR2DL3 confer different levels of protection to infectious disease. To investigate how changes in peptide repertoire may differentially affect NK cell reactivity, NK cells from KIR2DL2 and KIR2DL3 homozygous donors were tested for activity against different combinations of strong inhibitory (VAPWNSFAL), weak inhibitory (VAPWNSRAL), and antagonist peptide (VAPWNSDAL). KIR2DL3-positive NK cells were more sensitive to changes in the peptide content of MHC class I than KIR2DL2-positive NK cells. These differences were observed for the weakly inhibitory peptide VAPWNSRAL in single peptide and double peptide experiments (p < 0.01 and p < 0.03, respectively). More significant differences were observed in experiments using all three peptides (p < 0.0001). Mathematical modeling of the experimental data demonstrated that VAPWNSRAL was dominant over VAPWNSFAL in distinguishing KIR2DL3- from KIR2DL2-positive donors. Donors with different KIR genotypes have different responses to changes in the peptide bound by MHC class I. Differences in the response to the peptide content of MHC class I may be one mechanism underlying the protective effects of different KIR genes against infectious disease.

KIR3DL2 (CD158k) is a potential therapeutic target in primary cutaneous anaplastic large-cell lymphoma.

BACKGROUND: KIR3DL2, an inhibitory receptor expressed by natural killer cells and a subset of normal CD8(+) T cells, is aberrantly expressed in neoplastic cells in transformed mycosis fungoides and Sézary syndrome. Anti-KIR3DL2 targeted antibody therapy has shown potent activity in preclinical models for these diseases. OBJECTIVES: To examine the expression of KIR3DL2 and its potential use as a therapeutic target in patients with primary cutaneous anaplastic large-cell lymphoma (pcALCL), the most aggressive cutaneous CD30(+) lymphoproliferative disease. METHODS: Samples from 11 patients with pcALCL and three CD30(+) lymphoproliferative disease cell lines - Mac1, Mac2a and Mac2b - were used in KIR3DL2 expression studies using immunohistochemistry, flow cytometry and reverse-transcriptase quantitative polymerase chain reaction. The effect of IPH4102, a monoclonal humanized IgG1 targeting KIR3DL2, was assessed by in vitro cytotoxicity assays against Mac1, Mac2a and Mac2b using allogeneic peripheral blood mononuclear cells as effectors. RESULTS: KIR3DL2 mRNA and protein were found in all human samples of pcALCL, and in the Mac2a and Mac2b cell lines. KIR3DL2 protein expression was present on 85·8 ± 14·0% of CD30(+) skin-infiltrating tumour cells. In vitro functional studies showed that KIR3DL2(+) Mac2a and Mac2b pcALCL lines are sensitive to antibody-derived cytotoxicity mediated by IPH4102, through activation of natural killer cells, in a concentration-dependent manner. CONCLUSIONS: pcALCL tumour cells express KIR3DL2, and we provide preclinical proof of concept for the use of IPH4102, a humanized anti-KIR3DL2 antibody, to treat patients with primary cutaneous CD30(+) ALCL.

KIR2DL2 and KIR2DS2 as genetic markers to the methotrexate response in rheumatoid arthritis patients.

CONTEXT: Disease Modifying Anti-Rheumatic Drugs (DMARDs) are aimed to interfere with rheumatoid arthritis (RA) progression and reduce the joint damage; however, not all patients respond alike. Killer-cell immunoglobulin-like receptors (KIR) and their ligands, human leucocyte antigen class I (HLA-I), have been associated with RA pathology; therefore, KIR and HLA genes may influence the treatment response. MATERIALS AND METHODS: We evaluated the association of KIR genotype and their ligands HLA-C genes with the response to DMARDs in RA patients. We included 69 patients diagnosed with RA and 82 healthy individuals as the reference group. KIR and HLA-C genotyping was performed using SSP-PCR. RA patients were assessed at baseline and under treatment at 6 and 12 months; subsequently classified as responders and non-responders in each time period. We evaluated the association between DMARD response and genes using statistical analysis by using Fisher exact test with Bonferroni correction; results were regarded as statistically significant at p < 0.05. RESULTS: Significant difference was observed in gene frequencies of patients and the reference group, KIR2DL2 was associated with RA (p = 0.031, OR = 2.119). We also observed an association between KIR2DS2 and the response to methotrexate (MTX), moreover, the combination KIR2DL2+/KIR2DS2+ was more frequent in responders to MTX (p = 0.043). DISCUSSION AND CONCLUSIONS: In our results, responders and non-responders to DMARDs showed KIR2DS2 and KIR2DL2 different gene frequencies, therefore, these genes could be used as response predictors to DMARDs treatment. Thus, these genes were also associated with disease severity, as well as the treatment response possibly by the immunoregulatory function of NK cells.

Increased frequency and function of KIR2DL1-3⁺ NK cells in primary HIV-1 infection are determined by HLA-C group haplotypes.

The acquisition and maintenance of NK-cell function is mediated by inhibitory killer-cell immunoglobulin-like receptors (KIRs) through their interaction with HLA class I molecules. Recently, HLA-C expression levels were shown to be correlated with protection against multiple outcomes of HIV-1 infection; however, the underlying mechanisms are poorly understood. As HLA-C is the natural ligand for the inhibitory receptors KIR2DL1 and KIR2DL2/3, we sought to determine whether HLA-C group haplotypes affect NK-cell responses during primary HIV-1 infection. The phenotypes and functional capacity of NK cells derived from HIV-1-positive and HIV-1-negative individuals were assessed (N = 42 and N = 40, respectively). HIV-1 infection was associated with an increased frequency of KIR2DL1-3(+) NK cells. Further analysis showed that KIR2DL1(+) NK cells were selectively increased in individuals homozygous for HLA-C2, while HLA-C1-homozygous individuals displayed increased proportions of KIR2DL2/3(+) NK cells. KIR2DL1-3(+) NK cells were furthermore more polyfunctional during primary HIV-1 infection in individuals also encoding for their cognate HLA-C group haplotypes, as measured by degranulation and IFN-γ and TNF-α production. These results identify a novel relationship between HLA-C and KIR2DL(+) NK-cell subsets and demonstrate that HLA-C-mediated licensing modulates NK-cell responses to primary HIV-1 infection.

Inhibitory KIR/HLA incompatibility between sexual partners confers protection against HIV-1 transmission.

Killer immunoglobulin-like receptors (KIRs) regulate natural killer (NK) cells in a human leukocyte antigen (HLA)-dependent manner. KIR/HLA mismatched hematopoietic stem cell transplants induce alloreactive NK cells, which prevent leukemia relapse. Certain KIR/HLA combinations protect against HIV-1 infection, but the effect of KIR/HLA mismatches between sexual partners has never been investigated. In this study, we analyzed the effect of allogeneic KIR/HLA combinations on HIV-1 transmission in a West African population of HIV-1-discordant and concordant couples. HIV-1-discordant couples were characterized by recipient partners with homozygous KIR2DL2, and by a mismatched recipient partner KIR2DL1/HLA-C2 with index partner HLA-C1/C1 combination expected to allow licensed missing self NK cell killing of index partners' cells. HIV-1-concordant couples on the other hand were characterized by KIR2DL3 homozygous recipient partners with HLA-C1/C2 bearing index partners, resulting in a matched KIR/HLA combination expected to inhibit NK cell killing. In vitro cocultures of healthy donor-derived NK cells and HIV-1 patient-derived CD4(+) T cells confirmed the involvement of these allogeneic KIR/HLA combinations in NK cell-mediated CD4(+) T-cell killing. Our data suggest that KIR/HLA incompatibility between sexual partners confers protection against HIV-1 transmission and that this may be due to alloreactive NK cell killing of the HIV-1-infected partner's cells.

Large spectrum of HLA-C recognition by killer Ig-like receptor (KIR)2DL2 and KIR2DL3 and restricted C1 SPECIFICITY of KIR2DS2: dominant impact of KIR2DL2/KIR2DS2 on KIR2D NK cell repertoire formation.

The interactions of killer Ig-like receptor 2D (KIR2D) with HLA-C ligands contribute to functional NK cell education and regulate NK cell functions. Although simple alloreactive rules have been established for inhibitory KIR2DL, those governing activating KIR2DS function are still undefined, and those governing the formation of the KIR2D repertoire are still debated. In this study, we investigated the specificity of KIR2DL1/2/3 and KIR2DS1/2, dissected each KIR2D function, and assessed the impact of revisited specificities on the KIR2D NK cell repertoire formation from a large cohort of 159 KIR and HLA genotyped individuals. We report that KIR2DL2(+) and KIR2DL3(+) NK cells reacted similarly against HLA-C(+) target cells, irrespective of C1 or C2 allele expression. In contrast, KIR2DL1(+) NK cells specifically reacted against C2 alleles, suggesting a larger spectrum of HLA-C recognition by KIR2DL2 and KIR2DL3 than KIR2DL1. KIR2DS2(+) KIR2DL2(-) NK cell clones were C1-reactive irrespective of their HLA-C environment. However, when KIR2DS2 and KIR2DL2 were coexpressed, NK cell inhibition via KIR2DL2 overrode NK cell activation via KIR2DS2. In contrast, KIR2DL1 and KIR2DS2 had an additive enhancing effect on NK cell responses against C1C1 target cells. KIR2DL2/3/S2 NK cells predominated within the KIR repertoire in KIR2DL2/S2(+) individuals. In contrast, the KIR2DL1/S1 NK cell compartment is dominant in C2C2 KIR2DL2/S2(-) individuals. Moreover, our results suggest that together with KIR2DL2, activating KIR2DS1 and KIR2DS2 expression limits KIR2DL1 acquisition on NK cells. Altogether, our results suggest that the NK cell repertoire is remolded by the activating and inhibitory KIR2D and their cognate ligands.

Host genetic factors in susceptibility to herpes simplex type 1 virus infection: contribution of polymorphic genes at the interface of innate and adaptive immunity.

HSV-1 establishes life-long latency that can result in clinical relapses or in asymptomatic virus shedding. Although virtually all adults have been exposed to HSV-1, the clinical course varies remarkably. Genetic host variability could be related to this clinical diversity. In this study, we analyzed the contribution of gene families in chromosomes 1, 6, 12, and 19, which encode key regulators of the innate and adaptive immunity, in a cohort of 302 individuals. Class I and class II alleles of the HLA system, the copy-number variation of NK cell receptor genes (KIR and NKG2C), the combinations of killer cell Ig-like receptor and their HLA ligands, and CD16A and CD32A allotypes of variable affinity for IgG subclasses were all studied. Although no major susceptibility locus for HSV-1 was identified, our results show that the risk of suffering clinical HSV-1 infection is modified by MHC class I allotypes (B*18, C*15, and the group of alleles encoding A19), the high-affinity receptor/ligand pair KIR2DL2/HLA-C1, and the CD16A-158V/F dimorphism. Conversely, HLA class II and CD32A polymorphisms and NKG2C deletion did not seem to influence the clinical course of herpetic infection. Collectively, these findings support an important role in host defense against herpetic infection for several polymorphic genes implicated in adaptive immunity and in surveillance of its subversion. They confirm the crucial role of cytotoxic cells (CTL and NK) and the contribution of genetic diversity to the clinical course of HSV-1 infection.

CMV drives clonal expansion of NKG2C+ NK cells expressing self-specific KIRs in chronic hepatitis patients.

Natural killer (NK) cells are affected by infection with human cytomegalovirus (HCMV) manifested by increased expression of the HLA-E binding activating receptor NKG2C. We here show that HCMV seropositivity was associated with a profound expansion of NKG2C(+) CD56(dim) NK cells in patients with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Multi-color flow cytometry revealed that the expanded NKG2C(+) CD56(dim) NK cells displayed a highly differentiated phenotype, expressed high amounts of granzyme B and exhibited polyfunctional responses (CD107a, IFN-γ, and TNF-α) to stimulation with antibody-coated as well as HLA-E expressing target cells but not when stimulated with IL-12/IL-18. More importantly, NKG2C(+) CD56(dim) NK cells had a clonal expression pattern of inhibitory killer cell immunoglobulin-like receptors (KIRs) specific for self-HLA class I molecules, with predominant usage of KIR2DL2/3. KIR engagement dampened NKG2C-mediated activation suggesting that such biased expression of self-specific KIRs may preserve self-tolerance and limit immune-pathology during viral infection. Together, these findings shed new light on how the human NK-cell compartment adjusts to HCMV infection resulting in clonal expansion and differentiation of educated and polyfunctional NK cells.

Analyses of HLA-C-specific KIR repertoires in donors with group A and B haplotypes suggest a ligand-instructed model of NK cell receptor acquisition.

To determine the influence of KIR and HLA class I polymorphism on human NK cell repertoires, 32 different clonotypes representing all possible combinations of 4 inhibitory KIR and NKG2A were analyzed by multicolor flow cytometry. In donors homozygous for the common group A KIR haplotype, a significant influence of HLA-C ligands was seen: KIR repertoires were dominated by clonotypes expressing a single KIR for the respective cognate ligand, either the C1-specific KIR2DL3 or C2-specific KIR2DL1. In contrast, in donors possessing the polymorphic group B haplotypes, a similar adaptation to cognate HLA-C was lacking. We suggest that this discrepancy is largely the result of a suppressive effect of the group B-specific KIR2DL2 on the frequency of KIR2DL1(+) NK cells. In functional assays, KIR2DL2 not only recognized C1 but also C2 ligands, showing overlapping specificity with KIR2DL1. Moreover, using an NK cell differentiation assay we show sequential acquisition of KIR2DL2 before KIR2DL1 on developing NK cells. Together, these observations are compatible with a ligand-instructed model of NK cell education, in which recognition of HLA class I by an inhibitory receptor (KIR2DL2) suppresses subsequent expression of a second receptor (KIR2DL1) of related specificity. Importantly, the ligand-instructed model fits to the observed KIR repertoires in both broad KIR haplotype groups.

Killer Cell Immunoglobulin-Like Receptor Haplotype B Modulates Susceptibility to EBV-Associated Classic Hodgkin Lymphoma.

Tumor cells of classic Hodgkin lymphoma (cHL) are derived from antigen presenting B cells that are infected by Epstein Barr virus (EBV) in ~30% of patients. Polymorphic Killer cell immunoglobulin-like receptors (KIRs) expressed on NK cells interact with human leukocyte antigen (HLA) class I and play a key role in immune surveillance against virally infected cells and tumor cells. We investigated the effect of KIR types on cHL susceptibility overall (n=211) and in EBV-stratified subgroups using the Dutch GoNL cohort as controls (n=498). The frequency of the KIR haplotype B subgroup was significantly different between EBV+ and EBV- cHL patients (62% vs. 77%, p=0.04) and this difference was more pronounced in nodular sclerosis (NS) cHL (49% vs. 79%, p=0.0003). The frequency of KIR haplotype B subgroup was significantly lower in EBV+ NS cHL compared to controls (49% vs. 67%, p=0.01). Analyses of known KIR - HLA interaction pairs revealed lower carrier frequencies of KIR2DS2 - HLA-C1 (29% vs. 46%, p=0.03) and KIR2DL2 - HLA-C1 (29% vs. 45%, p=0.04) in EBV+ NS cHL patients compared to controls. Carriers of the KIR haplotype B subgroup are less likely to develop EBV+ NS cHL, probably because of a more efficient control over EBV-infected B cells.

CD158k and PD-1 expressions define heterogeneous subtypes of Sezary syndrome.

Sezary syndrome (SS) is a rare leukemic form of cutaneous T-cell lymphoma. Diagnosis mainly depends on flow cytometry, but results are not specific enough to be unequivocal. The difficulty in defining a single marker that could characterize Sezary cells may be the consequence of different pathological subtypes. In this study, we used multivariate flow cytometry analyses. We chose to investigate the expression of classical CD3, CD4, CD7, and CD26 and the new association of 2 markers CD158k and PD-1. We performed lymphocyte computational phenotypic analyses during diagnosis and follow-up of patients with SS to define new SS classes and improve the sensitivity of the diagnosis and the follow-up flow cytometry method. Three classes of SS, defined by different immunophenotypic profiles, CD158k+ SS, CD158k-PD-1+ SS, CD158k and PD-1 double-negative SS, showed different CD8+ and B-cell environments. Such a study could help to diagnose and define biological markers of susceptibility/resistance to treatment, including immunotherapy.

Preclinical characterization of 1-7F9, a novel human anti-KIR receptor therapeutic antibody that augments natural killer-mediated killing of tumor cells.

Inhibitory-cell killer immunoglobulin-like receptors (KIR) negatively regulate natural killer (NK) cell-mediated killing of HLA class I-expressing tumors. Lack of KIR-HLA class I interactions has been associated with potent NK-mediated antitumor efficacy and increased survival in acute myeloid leukemia (AML) patients upon haploidentical stem cell transplantation from KIR-mismatched donors. To exploit this pathway pharmacologically, we generated a fully human monoclonal antibody, 1-7F9, which cross-reacts with KIR2DL1, -2, and -3 receptors, and prevents their inhibitory signaling. The 1-7F9 monoclonal antibody augmented NK cell-mediated lysis of HLA-C-expressing tumor cells, including autologous AML blasts, but did not induce killing of normal peripheral blood mononuclear cells, suggesting a therapeutic window for preferential enhancement of NK-cell cytotoxicity against malignant target cells. Administration of 1-7F9 to KIR2DL3-transgenic mice resulted in dose-dependent rejection of HLA-Cw3-positive target cells. In an immunodeficient mouse model in which inoculation of human NK cells alone was unable to protect against lethal, autologous AML, preadministration of 1-7F9 resulted in long-term survival. These data show that 1-7F9 confers specific, stable blockade of KIR, boosting NK-mediated killing of HLA-matched AML blasts in vitro and in vivo, providing a preclinical basis for initiating phase 1 clinical trials with this candidate therapeutic antibody.

[Effects of blocking inhibitory KIR receptors on cytotoxic activity of human NK cells in vitro].

OBJECTIVE: To investigate the effect of blocking the inhibitory receptors KIR2DL1 and KIR2DL2/2DL3 with monoclonal antibody on cytotoxic activity of human NK cells. METHODS: Human peripheral blood NK cells were isolated by Rosettesep NK sorting kit. The cytotoxic activity of NK cells against human leukemia NB4, K-562, Raji cells and allogeneic mature or dendritic cells (DCs) was detected before or after KIR2DL1 and KIR2DL2/2DL3 were blocked. The effect of NK cells on T lymphocyte proliferation was detected by mixed lymphocyte reaction and TGF-ß1 concentration in culture supernatant was measured. RESULTS: The cytotoxicity of NK cells to NB4 cells was augmented with increasing concentration of the antibody. Combination of both antibodies enhanced killing activity of NK cells. NK cells had strong cytotoxicity to K-562 cells, but were not enhanced by the blockade of inhibitory receptors. The cytotoxicity to Raji cells was not evidently augmented. The cytotoxicity of NK cells to mature DC was enhanced remarkably with the increase of concentration of the antibodies (2.20% ±1.10% compared with 37.59% ±5.06%, P<0.05). In mixed lymphocyte reaction, the blockade of two antibodies enhanced the inhibition effect of NK cells on T cell proliferation (77.85% ± 8.31% compared with 43.05% ± 5.95%, P<0.05) and the content of TGF-ß1 in the supernatant was increased. CONCLUSION: The cytotoxic effects of human NK cells against target cells were significantly enhanced with the blockade of inhibitory KIR receptor; and the cytokine TGF-ß1 secreted by NK cells further inhibits T cells proliferation.

Natural Killer Cells Generated From Human Induced Pluripotent Stem Cells Mature to CD56brightCD16+NKp80+/-In-Vitro and Express KIR2DL2/DL3 and KIR3DL1.

The differentiation of human induced pluripotent stem cells (hiPSCs) into T and natural killer (NK) lymphocytes opens novel possibilities for developmental studies of immune cells and in-vitro generation of cell therapy products. In particular, iPSC-derived NK cells gained interest in adoptive anti-cancer immunotherapies, since they enable generation of homogenous populations of NK cells with and without genetic engineering that can be grown at clinical scale. However, the phenotype of in-vitro generated NK cells is not well characterized. NK cells derive in the bone marrow and mature in secondary lymphoid tissues through distinct stages from CD56brightCD16- to CD56dimCD16+ NK cells that represents the most abandoned population in peripheral blood. In this study, we efficiently generated CD56+CD16+CD3- NK lymphocytes from hiPSC and characterized NK-cell development by surface expression of NK-lineage markers. Hematopoietic priming of hiPSC resulted in 31.9% to 57.4% CD34+CD45+ hematopoietic progenitor cells (HPC) that did not require enrichment for NK lymphocyte propagation. HPC were further differentiated into NK cells on OP9-DL1 feeder cells resulting in high purity of CD56brightCD16- and CD56brightCD16+ NK cells. The output of generated NK cells increased up to 40% when OP9-DL1 feeder cells were inactivated with mitomycine C. CD7 expression could be detected from the first week of differentiation indicating priming towards the lymphoid lineage. CD56brightCD16-/+ NK cells expressed high levels of DNAM-1, CD69, natural killer cell receptors NKG2A and NKG2D, and natural cytotoxicity receptors NKp46, NKp44, NKp30. Expression of NKp80 on 40% of NK cells, and a perforin+ and granzyme B+ phenotype confirmed differentiation up to stage 4b. Killer cell immunoglobulin-like receptor KIR2DL2/DL3 and KIR3DL1 were found on up to 3 and 10% of mature NK cells, respectively. NK cells were functional in terms of cytotoxicity, degranulation and antibody-dependent cell-mediated cytotoxicity.