Assessment of killer cell immunoglobulinlike receptor expression and corresponding HLA class I phenotypes demonstrates heterogenous KIR expression independent of anticipated HLA class I ligands

The Influence of HLA and KIR Genes on Malignant Melanoma Development and Progression

Many studies have described the role of killer immunoglobulin-like receptors (KIRs) and their cognate human leukocyte antigen (HLA) class I ligands in the immune protection against melanoma, but the effect of these markers on intra-individual variations in tumor development and progression has remained less clear. We performed KIR, HLA, and KIR/ligand analysis in 283 patients with malignant melanoma in order to evaluate their integrated influence on disease stage and progression. The patients were grouped according to AJCC staging, histological type of the primary tumor, progression, and survival rate. Analysis of HLA class I alleles revealed positive association of HLA-C*14 (Pc = 0.026, OR = 5.99) and negative association of HLA-C*02 (Pc = 0.026, OR = 0.43) with the disease. Decreased frequency of KIR2DS5 was observed in patients with rapid progression, as compared to those with slow progression. KIR BB genotype was prevalent in patients with metastasis (p = 0.004, OR = 0.025). KIR AA genotype was nearly twice as frequent in rapidly progressive cases, but without statistical relevance (p = 0.055, OR = 2.6). Significantly increased frequency of KIR2DL2 in the presence of C1 ligand (strong inhibition) was found in patients with AJCC III and IV, as compared to individuals with AJCC I stage (p = 0.045, OR = 1.93). In summary, our data imply that KIR/ligand gene content in patients could modulate the disease course towards unfavorable tumor behavior.

Killer immunoglobulin-like receptor (KIR) and KIR-ligand genotype do not correlate with clinical outcome of renal cell carcinoma patients receiving high-dose IL2

NK cells play a role in many cancer immunotherapies. NK cell activity is tightly regulated by killer immunoglobulin-like receptor (KIR) and KIR-ligand interactions. Inhibitory KIR-ligands have been identified as HLA molecules, while activating KIR-ligands are largely unknown. Individuals that have not inherited the corresponding KIR-ligand for at least one inhibitory KIR gene are termed the "KIR-ligand missing" genotype, and they are thought to have a subset of NK cells that express inhibitory KIRs for which the corresponding KIR-ligand is missing on autologous tissue, and thus will not be inhibited through KIR-ligand recognition. In some settings where an anticancer immunotherapeutic effect is likely mediated by NK cells, individuals with a KIR-ligand missing genotype have shown improved clinical outcome compared to individuals with an "all KIR-ligands present" genotype. In addition, patients receiving hematopoietic stem cell transplants for leukemia may do better if their donor has more activating KIR genes (i.e., KIR haplotype-B). In a recent multi-institution clinical trial of patients with metastatic renal cell carcinoma receiving high-dose IL2 (HD-IL2), 25 % of patients showed a complete or partial tumor response to this therapy. We genotyped KIR and KIR-ligand genes for these patients (n = 107) and tested whether KIR/KIR-ligand genotypes correlated with patient clinical outcomes. In these analyses, we did not find any significant association of KIR/KIR-ligand genotype (either KIR-ligand missing or the presence of KIR haplotype-B) with patient outcome in response to the HD-IL2 therapy.

KIR and HLA haplotype analysis in a family lacking the KIR 2DL1-2DP1 genes

The killer cell immunoglobulin-like receptor (KIR) gene cluster exhibits extensive allelic and haplotypic diversity that is observed as presence/absence of genes, resulting in expansion and contraction of KIR haplotypes and by allelic variation of individual KIR genes. We report a case of KIR pseudogene 2DP1 and 2DL1 gene absence in members of one family with the children suffering from acute myelogenous leukemia (AML). Killer cell immunoglobulin-like receptor low resolution genotyping was performed by the polymerase chain reaction (PCR)-sequence-specific primers (SSP)/sequence-specific oligonucleotide (SSO) method and haplotype assignment was done by gene content analysis. Both parents and the maternal grandfather, shared the same Cen-B2 KIR haplotype, containing KIR 3DL3, -2DS2, -2DL2 and -3DP1 genes. The second haplotype in the KIR genotype of the mother and grandfather was Tel-A1 with KIR 2DL4 (normal and deleted variant), -3DL1, -22 bp deletion variant of the 2DS4 gene and -3DL2, while the second haplotype in the KIR genotype of the father was Tel-B1 with 2DL4 (normal variant), -3DS1, -2DL5, -2DS5, -2DS1 and 3DL2 genes. Haplotype analysis in all three offsprings revealed that the children inherited the Cen-B2 haplotype with the same gene content but two of the children inherited a deleted variant of the 2DL4 gene, while the third child inherited a normal one. The second haplotype of all three offspring contained KIR 2DL4, -2DL5, -2DS1, -2DS4 (del 22bp variant), -2DS5, -3DL1 and -3DL2 genes, which was the basis of the assumption that there is a hybrid haplotype and that the present 3DL1 gene is a variant of the 3DS1 gene. Due to consanguinity among the ancestors, the results of KIR segregation analysis showed the existence of a very rare KIR genotype in the offspring. The family who is the subject of this case is even more interesting because the father was 10/10 human leukocyte antigen (HLA)-matched to his daughter, all members of the family have the “best” donor KIR-B content and the presence of a rare KIR genotype with KIR 2DP1-2DL1 genes absence.

KIR2DS4 and Its Variant KIR1D Are Associated with Acute Graft-versus-Host Disease, Cytomegalovirus, and Overall Survival after Sibling-Related HLA-Matched Transplantation in Patients with Donors with KIR Gene Haplotype A

Outcomes for hematopoietic stem cell transplantation (HSCT) in various donor and recipient killer immunoglobulin-like receptor (KIR) genotypes have been studied extensively. The associations between KIR2DS4 and its variant KIR1D with outcomes of HSCT from a sibling-related HLA-matched donor with KIR haplotype A have not been explored, however. To study this, we genotyped donor-recipient pairs and divided 165 recipients of HSCT from a KIR gene haplotype A donor into 3 groups: 2DS4+/2DS4+ (2 intact KIR2DS4 alleles), 2DS4+/1D+ (heterozygous), and 1D+/1D+ (homozygous for the deletion variant KIR1D). No difference in the recovery of neutrophils and platelets among the 3 groups was observed. The cumulative incidence of grade III-IV acute graft-versus-host disease (aGVHD) within day +100 was 28.94% in the 2DS4+/2DS4+ group, 14.11% in the 2DS4+/1D+ group, and 44.44% in the 1D+/1D+ group (P = .0159). Multivariate analysis identified 1D+/1D+ as an independent risk factor for aGVHD (hazard ratio [HR], 4.221; 95% confidence interval [CI], 1.470 to 12.124; P = .007). In contrast, the cumulative incidences of chronic GVHD, 3-year cumulative relapse, and treatment-related mortality did not differ significantly among the 3 groups. The rate of cytomegalovirus (CMV) reactivation was 46.96% in the 2DS4+/2DS4+ group, 20.16% in the 2DS4+/1D+ group, and 53.25% in the 1D+/1D+ group (P = .0017). Multivariate analysis identified 2DS4+/1D+ as an independent protective factor for CMV reactivation (HR, 0.268; 95% CI, 0.125 to 0.574; P = .001). Although overall survival (OS) did not differ among the groups in the first year, the 2DS4(+)/2DS4(+) group had significantly better OS than the other groups after 1 year (P = .0361). In patients with advanced-stage disease, the 3-year probability of disease-free survival was 51.06% in the 2DS4+/2DS4+ group, 34.01% in the 2DS4+/1D+ group, and 0% in the 1D+/1D+ group (P = .0314). Collectively, our data suggest that the KIR 2DS4/1D allelic variance is associated with the outcome of sibling-related HLA-matched HSCT, and that donor subclassification of KIR 2DS4/1D alleles should be considered in this setting.

Clinical grade purification and expansion of NK cell products for an optimized manufacturing protocol

Allogeneic natural killer (NK) cells are used for adoptive immunotherapy after stem cell transplantation. In order to overcome technical limitations in NK cell purification and activation, the following study investigates the impact of different variables on NK cell recovery, cytotoxicity, and T-cell depletion during good manufacturing practice (GMP)-grade NK cell selection. Forty NK cell products were derived from 54 unstimulated donor leukaphereses using immunomagnetic CD3 T-cell depletion, followed by a CD56 cell enrichment step. For T-cell depletion, either the depletion 2.1 program in single or double procedure (D2.1_1depl, n = 18; D2.1_2depl, n = 13) or the faster depletion 3.1 (D3.1, n = 9) was used on the CliniMACS instrument. Seventeen purified NK cell products were activated in vitro by IL-2 for 12 days. The whole process resulted in a median number of 7.59 × 10⁸ CD56⁺CD3⁻ cells with both purity and viability of 94%, respectively. The T-cell depletion was significantly better using D2.1_1depl/2depl compared to D3.1 (log 4.6/log 4.9 vs. log 3.7; p < 0.01) and double procedure in two stages led always to residual T cells below 0.1%. In contrast D3.1 was superior to D2.1_1depl/2depl with regard to recovery of CD56⁺CD3⁻ NK cells (68% vs. 41%/38%). Concomitant monocytes and especially IL-2 activation led to increased NK cell activity against malignant target cells compared to unstimulated NK cells, which correlated with both up-regulation of natural cytotoxicity receptors and intracellular signaling. Overall, wide variations in the NK cell expansion rate and the distribution of NK cell subpopulations were found. In conclusion, our results indicate that GMP-grade purification of NK cells might be improved by a sequential processing of T-cell depletion program D2.1 and D3.1. In addition NK cell expansion protocols need to be further optimized.

IL-2 stimulated but not unstimulated NK cells induce selective disappearance of peripheral blood cells: concomitant results to a phase I/II study

In an ongoing clinical phase I/II study, 16 pediatric patients suffering from high risk leukemia/tumors received highly purified donor natural killer (NK) cell immunotherapy (NK-DLI) at day (+3) +40 and +100 post haploidentical stem cell transplantation. However, literature about the influence of NK-DLI on recipient's immune system is scarce. Here we present concomitant results of a noninvasive in vivo monitoring approach of recipient's peripheral blood (PB) cells after transfer of either unstimulated (NK-DLI(unstim)) or IL-2 (1000 U/ml, 9-14 days) activated NK cells (NK-DLI(IL-2 stim)) along with their ex vivo secreted cytokine/chemokines. We performed phenotypical and functional characterizations of the NK-DLIs, detailed flow cytometric analyses of various PB cells and comprehensive cytokine/chemokine arrays before and after NK-DLI. Patients of both groups were comparable with regard to remission status, immune reconstitution, donor chimerism, KIR mismatching, stem cell and NK-DLI dose. Only after NK-DLI(IL-2 stim) was a rapid, almost complete loss of CD56(bright)CD16(dim/-) immune regulatory and CD56(dim)CD16(+) cytotoxic NK cells, monocytes, dendritic cells and eosinophils from PB circulation seen 10 min after infusion, while neutrophils significantly increased. The reduction of NK cells was due to both, a decrease in patients' own CD69(-) NCR(low)CD62L(+) NK cells as well as to a diminishing of the transferred cells from the NK-DLI(IL-2 stim) with the CD56(bright)CD16(+/-)CD69(+)NCR(high)CD62L(-) phenotype. All cell counts recovered within the next 24 h. Transfer of NK-DLI(IL-2 stim) translated into significantly increased levels of various cytokines/chemokines (i.e. IFN-γ, IL-6, MIP-1β) in patients' PB. Those remained stable for at least 1 h, presumably leading to endothelial activation, leukocyte adhesion and/or extravasation. In contrast, NK-DLI(unstim) did not cause any of the observed effects. In conclusion, we assume that the adoptive transfer of NK-DLI(IL-2 stim) under the influence of ex vivo and in vivo secreted cytokines/chemokines may promote NK cell trafficking and therefore might enhance efficacy of immunotherapy.

The cytotoxic potential of interleukin-15-stimulated cytokine-induced killer cells against leukemia cells

BACKGROUND AIMS

Cytokine-induced killer (CIK) cells may serve as an alternative approach to adoptive donor lymphocyte infusions (DLI) for patients with acute leukemia relapsing after haplo-identical hematopoietic stem cell transplantation (HSCT). We investigated the feasibility of enhancing CIK cell-mediated cytotoxicity by interleukin (IL)-15 against acute myeloid and lymphoblastic leukemia/lymphoma cells.

METHODS

CIK cells were activated using IL-2 (CIK(IL-2)) or IL-15 (CIK(IL-15)) and phenotypically analyzed by fluorescence-activated cell sorting (FACS). Cytotoxic potential was measured by europium release assay.

RESULTS

CIK(IL-2) cells showed potent cytotoxicity against the T-lymphoma cell line H9, T-cell acute lymphoblastic leukemia (T-ALL) cell line MOLT-4 and subtype M4 acute myeloid leukemia (AML) cell line THP-1, but low cytotoxicity against the precursor B (pB)-cell ALL cell line Tanoue. IL-15 stimulation resulted in a significant enhancement of CIK cell-mediated cytotoxicity against acute lymphoblastic leukemia/lymphoma cell lines as well as against primary acute myeloid and defined lymphoblastic leukemia cells. However, the alloreactive potential of CIK(IL-15) cells remained low. Further analysis of CIK(IL-15) cells demonstrated that the NKG2D receptor is apparently involved in the recognition of target cells whereas killer-cell immunoglobulin-like receptor (KIR)-HLA mismatches contributed to a lesser extent to the CIK(IL-15) cell-mediated cytotoxicity. In this context, CD3 (+) CD8 (+) CD25 (+) CD56(-) CIK(IL-15) cell subpopulations were more effective in the lysis of AML cells, in contrast with CD56 (+) CIK(IL-15) cells, which showed the highest cytotoxic potential against ALL cells.

CONCLUSIONS

This study provides the first evidence that CIK(IL-15) cells may offer a therapeutic option for patients with refractory or relapsed leukemia following haplo-identical HSCT.

CpG array analysis of histone H3 lysine 4 trimethylation in peripheral blood mononuclear cells of uremia patients

Studies of the epigenome have attracted little interest in nephrology, especially in uremia. Several lines of evidence have suggested that there are links between genomic DNA hypomethylation and cardiovascular complications in uremia patients. However, to date, our knowledge about the alterations in histone methylation in uremia is unknown. H3K4me3 variations were analyzed in peripheral blood mononuclear cells from 20 uremia patients and 20 healthy subjects, using chromatin immunoprecipitation microarray (ChIP-chip) approach. ChIP-real-time polymerase chain reaction (PCR) was used to validate the microarray results. mRNA expression and DNA methylation status can be further analyzed by quantitative (q) reverse transcription (RT)-PCR and methyl-DNA immunoprecipitation (MeDIP)-qPCR, respectively. Seven hundred twenty-six increased and 218 decreased H3K4me3 genes displaying significant H3K4me3 differences were found in uremia patients compared with healthy subjects. The results of ChIP-real-time PCR coincided well with microarray results. Expression analysis by qRT-PCR revealed positive correlations between mRNA and H3K4me3 levels. Aberrant DNA methylation can also be found on selected positive genes (CNOT1 PLTP EDG1 TCF3 KIR3DL2). In addition, we even found that there is an inverse relationship between H3K4me3 and promoter DNA methylation in uremia patients. Our studies indicate that there are significant alterations of H3K4me3 in uremia patients; these significant H3K4me3 candidates may help to explain the immunological disturbance and high cardiovascular complications in uremia patients. Such novel findings show the significance of H3K4me3 as a potential biomarker or promising target for epigenetic-based uremia therapies.

Age-related changes in natural killer cell receptors from childhood through old age

Most studies on natural killer (NK) cells and aging have focused on overall cell numbers and global cytotoxic activity. NK cell functions are controlled by surface receptors belonging to three major families: killer cell immunoglobulin-like receptors (KIRs), natural cytotoxicity receptors (NCRs), and C-type lectins. The expression of these receptors was investigated from childhood through old age in T, NKT- and NK cells and also in the CD56(dim) (cytotoxic) and CD56(bright) (responsible for cytokine production) NK cell subsets. A decrease in the expression of activating receptors (NKp30 and NKp46) was observed in NK cells in elderly individuals. KIR expression was increased only in the CD56(bright) subset. Children presented similar results regarding expression of NKp30 and KIR, but not NKp46. NKG2D expression was decreased in T cells of elderly subjects. Analysis of KIR genotype revealed that KIR2DL5 and KIR2DS3 were significantly associated with old age. Cytotoxic activity was preserved from childhood through old age, suggesting that the increase of the absolute number of CD56(dim), observed in elderly, may represent a compensatory mechanism for the receptor expression alterations. This initial study provides the framework for more focused studies of this subject, which are necessary to determine whether the changing balance of NK receptor expression may influence susceptibility to infectious, inflammatory, and neoplastic diseases.

Killer cell immunoglobulin-like receptor gene diversity in the Saudi population

Killer cell immunoglobulin-like receptors (KIRs) influence the outcome of haematopoetic stem cell transplantation by modulating the cytotoxic ability of natural killer (NK) cells and a subset of T cells. KIRs are also highly polymorphic and could therefore be good population genetic markers, much like their human leukocyte antigen (HLA) ligands. This study represents the first report on distribution of 16 KIR genes in 162 unrelated healthy Saudi individuals. All the 16 KIR genes were observed in the studied population and the four framework genes (KIR2DL4, 3DL2, 3DL3 and 3DP1) were present in all individuals. Forty- one distinct KIR profiles were expressed in our population, 11 of which had not been previously described in other populations including the Middle Eastern population. AA1, the most common genotypic profile was observed at a frequency of 26.5%. The group A haplotype was more frequent (53%) in the Saudi population compared to the group B haplotype (47%). The pattern of the inhibitory KIR/HLA ligands were also analyzed and 52.3% of the Saudi population was found to express two pairs of the inhibitory KIR/HLA-C. The KIR gene frequencies suggests that the Saudi population shares common general features with the Middle Eastern and other populations, but still has its own unique frequencies of several KIR loci.

IL-2-driven regulation of NK cell receptors with regard to the distribution of CD16+ and CD16- subpopulations and in vivo influence after haploidentical NK cell infusion

To characterize natural killer (NK) cell subpopulations during activation, we analyzed the NK cell receptor repertoire and functionality of purified clinical scale CD56CD3 donor NK cells during stimulation with 1000 U/mL interleukin (IL)-2 for up to 14 days. In a phase I/II trial, we investigated the efficacy and feasibility of nonidentical NK cell infusion in patients with neuroblastoma after haploidentical stem cell transplantation. After IL-2 stimulation, large differences in the distribution of CD16 and CD16 subpopulations were found in 12 donors. Thereby, surface expression for all natural cytotoxicity receptors (NCRs) and NKG2D increased. In addition, killer cell immunoglobulin-like receptor (KIR) NK cells were overgrown by KIR proportion and the homing receptor CD62L was lost during stimulation. NK cell cytotoxicity against K562 and neuroblastoma cells increased and significantly higher cytokine secretion (eg, interferon-gamma, tumor necrosis factor-beta, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta) was observed after IL-2 stimulation compared with freshly isolated NK cells. However, NK cells of donors showing an initially enhanced cytotoxicity combined with NCR and CD69 expression, seemed to be exhausted and did not favor a stimulation period over 9 days. When IL-2-stimulated NK cells were given to transplant recipients, they induced a decrease of peripheral blood NK, in particular of CD56-NK cells. Our data indicate that IL-2 stimulation increases the expression of activating receptors and emphasizes mechanisms beside KIR/human leukocyte antigen. Furthermore, the results suggest that the expansion period of purified NK cells has to be individualized to optimize NK cell immunotherapy.

Differential RNA expression of KIR alleles

Allelic polymorphisms dramatically influence the phenotype of human killer immunoglobulin-like receptors (KIR) by modifying their expression in cell surfaces. It is unclear though to what extent this involves transcriptional or post-transcriptional mechanisms, as quantitative RNA expression of KIR alleles has not been systematically compared. We measured RNA transcript abundance of common KIR alleles by real-time quantitative reverse transcriptase PCR (RT-PCR) in 85 PBL samples that were allele-typed in parallel. Allele type showed little influence on transcript abundance for a given KIR gene, except for: (1) KIR2DL5B*002, which consistently showed undetectable transcripts levels; (2) truncated KIR2DS4 alleles, associated with lowered expression levels; and (3) alleles of KIR2DL4 with a single-base deletion, associated with higher expression than average. Lowered levels of truncated KIR2DS4 transcripts were confirmed by dot blot of RT-PCR products, indicating imbalanced allelic RNA expression in heterozygote genotypes containing these alleles. Imbalanced expression of truncated KIR2DS4 alleles was corroborated in family samples. Gene copy number of KIR2DL1, KIR2DL3 and KIR3DL1 influenced RNA expression, genotypes with a single copy expressing on average lower transcript amounts than those with two copies. The data show that for a given KIR gene, the common allele types found in our population express comparable RNA levels, except truncated or null alleles. Thus, variation of KIR expression on cell surfaces more likely involves post-transcriptional mechanisms.

Distribution of killer cell immunoglobulinlike receptors in the Macedonian population

The aim of this study was to analyze killer immunoglobulinlike receptor (KIR) gene polymorphism in the Macedonian population. The study sample consists of 214 healthy unrelated individuals, aged 20-35 years. All individuals are of Macedonian origin and nationality, and residents of different geographic regions. The population genetics analysis package, Arlequin, was used for analysis of the data. We found that all 16 KIR genes were observed in the Macedonian population and framework genes KIR3DL3, KIR2DL4, and KIR3DL2 were present in all individuals. A total of 56 different KIR genotypes were found in the Macedonian population, based on the presence of 16 KIR genes. Neighbor-joining phylogenetic tree, constructed on the basis of standard genetic distances of KIR genes, shows that Macedonian population is in the same cluster with England West Midlands Indian Asian, Brazil SouthEast Caucasian, Romania Caucasians, Spain Basque, England West Midlands Caucasian, France Reunion, and Spain Granada populations. The frequency of KIR loci in Macedonian population shares several general features with other Caucasoid populations studied before.

KIR/HLA ligand incompatibility in kidney transplantation

BACKGROUND

The polymorphic family of killer-cell immunoglobulin-like receptors (KIRs) consists of activating and inhibitory receptors expressed by natural killer (NK) cells and effector T cells that recognize human leukocyte antigen (HLA) class I ligands. It has been suggested that KIR/HLA incompatibility exerts beneficial effects in hematopoietic stem cell transplantation.

METHODS

To elucidate whether certain receptor-ligand combinations between recipient KIR and donor HLA antigens lead to enhanced alloreactivity of NK cells associated with acute rejection (aRx) after kidney transplantation, we analyzed the entirety of matches/mismatches between KIR genes and known HLA ligands for aRx patients (n=105) compared to patients with stable renal function (n=119).

RESULTS

Whereas HLA-C ligand incompatibility between donor and recipient has no influence on aRx, grafts derived from donors homozygous for HLA-C group 2 alleles seem to demonstrate a better outcome (P=0.052). Additionally, a higher number of inhibitory receptors in the recipient's genotype (P=0.042), a significant higher number of matches for the receptors KIR2DL2/DS2 (P=0.004), as well as a higher number of mismatches for KIR2DL3 (P=0.014) could be observed for patients with stable renal function.

CONCLUSION

Our data illustrate that certain KIR/HLA class I ligand combinations between donor and recipient might influence graft short-term outcome after renal transplantation.

Age-dependent alterations of the T cell repertoire and functional diversity of T cells of the aged

The aging immune system is characterized by the contraction of T cell receptor (TCR) diversity and the de novo expression of NKrelated receptors (NKR) on oligoclonal T cells. NKR+ T cells likely represent a secondary immune diversification as a biological adaptation of aging to ensure host defense despite shrinkage of the TCR repertoire. NKRs are expressed in various combinations even among TCR-identical cells, and are capable of triggering effector pathways in either TCR-independent or TCR-dependent fashion. Understanding the biology of NKR+ T cells will be pivotal to the development of strategies to enhance immunity in the elderly.

Genotypic evaluation of killer immunoglobulin-like receptors in NK-type lymphoproliferative disease of granular lymphocytes

Using polymerase chain reaction (PCR)-based sequence-specific primers, the killer immunoglobulin-like receptor (KIR) genotypes of 35 patients with natural killer (NK)-type lymphoproliferative disease of granular lymphocytes and of 50 normal subjects were investigated to evaluate whether genes coding for activating KIRs were more frequently detected in patients with NK-lymphoproliferative disease of granular lymphocytes (LDGL). Genotype frequency indicated that the most frequently found gene content was eight genes in controls and 14 in patients (P<0.05). The KIR genotype analysis revealed that patient and, surprisingly, control KIR genotypes preferentially consisted of type B haplotypes characterized by the presence of multiple-activating KIRs. Evidence was also provided that the same KIR genotype was shared by a variable number of patients. Interestingly, the recurrent genotypes observed in the patient group were not found in controls. Concerning inhibitory genes, KIR2DL5a and 2DL5b were more frequently detected in patients than in controls (P<0.01), likely representing a discrete feature of the genetic repertoire of the patients. KIR gene repertoire analysis in patients suggests that the susceptibility to NK-LDGL might be related to the presence of activating KIR genes and supports the concept that these receptors may be involved in the priming of granular lymphocytes (GL) proliferation. Population analysis might disclose a genetic background predisposing to this disease.

Distribution of killer cell immunoglobulin-like receptors genes in the Italian Caucasian population

Background

Killer cell immunoglobulin-like receptors (KIRs) are a family of inhibitory and activatory receptors that are expressed by most natural killer (NK) cells. The KIR gene family is polymorphic: genomic diversity is achieved through differences in gene content and allelic polymorphism. The number of KIR loci has been reported to vary among individuals, resulting in different KIR haplotypes. In this study we report the genotypic structure of KIRs in 217 unrelated healthy Italian individuals from 22 immunogenetics laboratories, located in the northern, central and southern regions of Italy.

Methods

Two hundred and seventeen DNA samples were studied by a low resolution PCR-SSP kit designed to identify all KIR genes.

Results

All 17 KIR genes were observed in the population with different frequencies than other Caucasian and non-Caucasian populations; framework genes KIR3DL3, KIR3DP1, KIR2DL4 and KIR3DL2 were present in all individuals. Sixty-five different profiles were found in this Italian population study. Haplotype A remains the most prevalent and genotype 1, with a frequency of 28.5%, is the most commonly observed in the Italian population.

Conclusion

The Italian Caucasian population shows polymorphism of the KIR gene family like other Caucasian and non-Caucasian populations. Although 64 genotypes have been observed, genotype 1 remains the most frequent as already observed in other populations. Such knowledge of the KIR gene distribution in populations is very useful in the study of associations with diseases and in selection of donors for haploidentical bone marrow transplantation.

Analysis of KIR2D receptors on peripheral blood lymphocytes from liver graft recipients

KIR2D receptors are killer cell immunoglobulin-like receptors (KIRs) specific for HLA-C epitopes, that are expressed on NK cells as well as on minor peripheral blood T-cell subsets, and are able to control NK and T cells activity. The present work explores NK, and particularly CD8(+) T cells expressing KIR2D2L1/S1 (CD158a) or KIR2D2L2/3/S2 (CD158b) receptors in liver graft alloresponse. Flow cytometry was used to analyse peripheral blood mononuclear cells stained with anti-CD158a and anti-CD158b antibodies from 110 liver recipients and 46 healthy controls, previous to and along the first month after transplantation. Pre-transplantation data shows that both CD158a and CD158b molecules can be detected on NK and T cells from all patients and controls, but both KIR2D(+)NK cells are significantly under-represented in patients respect to controls (P<0.001), and CD3(+)CD8(+)CD158a(+) cells decreased particularly in patients suffering from acute rejection (4.03+/-1.33 cells/microL) compared with controls (7.8+/-2.4 cells/microL). Following transplantation, KIR2D(+)CD8(+) T-cell repertoires increased through the first month, mainly in recipients with a good graft acceptance. In summary, monitoring of KIR2D(+)CD8(+) T cells, particularly KIR2DL1/S1(+)CD8(+) T cells at pre-transplant, and both KIR2DL1/S1(+) and KIR2DL2/3/S2(+) T-cell subsets at early post-transplant period, could offer useful information for clinical follow-up of liver grafts.

Natural Killer Receptors on CD8 T Cells and Natural Killer Cells from Different HLA-C Phenotypes in Melanoma Patients

PURPOSE

Because immune mechanisms involved in cutaneous melanoma have not been fully elucidated, efforts have been made to achieve prognosis markers and potential targets for immune therapies, but they have not been entirely fruitful thus far. Therefore, the goal of this study was to investigate the involvement of early changes in CD8 T cells and CD56 natural killer (NK) cells expressing NK receptors in different HLA-C dimorphism groups of melanoma patients.

EXPERIMENTAL DESIGN

CD8 T cells and CD56 NK cells were analyzed in 41 patients and 39 sex- and age-matched controls with different HLA-C genotypes by flow cytometry. HLA-C dimorphism at position 80 was tested by PCR sequence-specific primers and PCR sequence-specific oligonucleotide to examine whether it could mediate in the emergence of cells expressing killer cell immunoglobulin-like receptors.

RESULTS

Thirty-five of 41 patients had benign sentinel node, and showed an imbalance in the absolute number of CD8(+)DR(+) or CD8(+)CD161(+) peripheral blood T cells according to the CD28 coexpression compared with controls. CD8(+)CD28(-)CD158a(+) T and CD56(+)CD158a(+) NK cells were significantly increased in HLA-C(Lys80) homozygous nonmetastatic patients, whereas only CD56(+)CD158a(+) NK cells increased in heterozygous ones. An up-regulation of the CD158a KIR receptor was also seen on NK cells but not in T cells of patients at advanced disease stages.

CONCLUSIONS

This work provides, for the first time, evidence of immune activation in early stages of cutaneous melanoma, together with an increase of cells expressing CD158a in patients bearing the corresponding HLA-C ligand, which may be important to evaluate the disease progression and to use individualized immune therapeutic approaches.

Activating KIR genes are associated with CMV reactivation and survival after non-T-cell depleted HLA-identical sibling bone marrow transplantation for malignant disorders

Combinations of HLA and killer immunoglobulin-like receptors (KIR) may affect outcome in T-cell depleted haematopoietic stem cell transplantation (HSCT). The KIR gene family includes inhibitory (KIR2DL and 3DL) and activating receptors (KIR2DS). Ligands are HLA-C (KIR2D) and HLA-Bw4 (KIR3DL1) for inhibitory KIR and are still unknown for activating KIR. The impact of activating KIR genotypes from donor and recipient is poorly documented in HSCT outcome. Here, HLA and KIR genotypes were determined in 131 pairs from non-T-cell depleted HLA-identical sibling HSCT. No effect of 'missing KIR ligand' was detected on acute graft-versus-host disease (GVHD), relapse, survival or infections even in myeloid malignancies. However, additional activating KIR genes in the donor compared to the recipient's genotype or an identity between donor and recipient activating KIR genotypes was associated with a lower transplant-related mortality (TRM) (P=0.005) and in a multivariate analysis with a better survival (P=0.02, HR=0.28; P=0.013, HR=0.29) and a lower incidence of cytomegalovirus (CMV) reactivation (P=0.009, HR=0.36). These data highlight the impact of donor-activating KIR genes on TRM, overall survival and CMV reactivation in HLA-identical sibling HSCT.

Inhibitory and activatory KIR gene frequencies in the Polish population

Killer cell immunoglobulin-like receptors (KIRs) present on natural killer cells and minor subpopulations of T cells recognize class I human leukocyte antigen (HLA) molecules on the surface of target cells. Human individuals differ by the presence or absence of some KIR genes on their chromosomes (haplotypic polymorphism). As KIRs (especially two-immunoglobulin-domain-like containing, or KIR2D, molecules) are important for the outcome of tissue (particularly for haematopoietic stem cell) transplantation and possibly for pregnancy, the knowledge of KIR gene distribution in a given human population is of practical value. Therefore, we tested 175 healthy individuals from Poland for the presence or absence of these KIR genes which show haplotypic polymorphism and are expressed. Results were compared with those published for other human populations, showing close relations with other Caucasoids.

Distribution of killer-cell immunoglobulin-like receptor (KIR) in Comoros and Southeast France

Killer-cell immunoglobulin-like receptors (KIRs) expressed by natural killer cells are cell surface molecules able to recognize groups of HLA class I alleles. The number and distribution of KIR genes vary among individuals and populations. The aim of this study is to analyse the KIR gene content in a Comorian population in order to investigate genetic relationships with other populations and to reconstruct past migration events. The Comorian population consisted of 54 unrelated immigrants living in France and a control population consisted of 38 individuals from Southeast France. We investigated the presence or absence of 15 KIR genes, two pseudogenes expressed and non-expressed forms of KIR2DL5 and the two major subtype full-length and deleted forms of KIR2DS4. All individuals were typed positive for the framework genes, i.e. KIR2DL4, KIR3DL2 and KIR3DL3, and the two pseudogenes KIR3DP1 and KIR2DP1. The frequencies of full-length KIR2DS4 (*00101/00102/002) were lower in the French population (F = 29%) than in the Comorian population (F = 72%) (P(c) < 0.05). No significant differences were found for other KIR genes. A total of 11 genotypes were identified in the Southeast French population and 22 genotypes in the Comorian population. The most common genotype (2DL1, 2DL3, 2DL4, 3DL1, 3DL2, 3DL3 and 2DS4) accounted for 41% in the Comorian population and 34% in the Southeast French population. Principal component analysis using KIR gene data from 20 populations was performed to determine genetic differences and relations between populations. The Comorian population exhibited closest kinship with Africans and Asians. As KIR gene content is heterogeneous among ethnic groups, it can probably be used to assess the genetic relationships among populations from different geographic areas.

Diversity of NKR expression in aging T cells and in T cells of the aged: the new frontier into the exploration of protective immunity in the elderly

Aging in the immune system is characterized by the contraction of the lymphocyte repertoire, exemplified by long-lived oligoclonal T cells that pervade the peripheral circulation. T-cell receptor (TCR) repertoire contraction likely explains the decline in immunity with chronological age as evidenced by the increased morbidity and mortality to common and new infections, and the low rates of protective responses to vaccination in the elderly. Interestingly, in vitro senescence models and cross sectional ex vivo studies have consistently demonstrated that senescent (or pre-senescent) T cells and T cells of the aged express unusually high densities of receptors that are normally found on natural killer (NK) cells, the killer cell immunoglobulin-like receptors (KIR) being the most diverse NK receptors (NKR). Molecular studies also show that T cells are programmed to express NKRs/KIRs, and T-cell clonal lineages express a variety of NKRs towards the end stages of their replicative lifespan. We propose that NKR/KIR induction in aging T cells is an adaptational diversification of the immune repertoire. We suggest that NKR/KIR expression in oligoclonal senescent and pre-senescent T cells is a compensatory adaptation to maintain immune competence despite the overall contraction in TCR diversity with aging. NKRs comprise a diverse superfamily of receptors. Mounting evidence for NKR/KIR signaling pathways in T cells divergent from those seen in NK cells indicate that senescent NKR(+)T cells are unique immune effectors. We suggest that appreciation of the functional diversity of these unusual NK-like T cells is central to the creative development of new strategies to enhance protective immunity in the aged.

The antileukemia effect of HLA-matched NK and NK-T cells in chronic myelogenous leukemia involves NKG2D-target-cell interactions

To study natural killer (NK) cell-mediated antileukemic activity in chronic myelogenous leukemia (CML), we investigated the ability of HLA-matched and mismatched CD56(+) cells to inhibit granulocyte macrophage-colony-forming unit (CFU-GM) formation by leukemic CD34(+) cells. In 14 HLA-identical donor-recipient pairs, donor CD56(+) cells inhibited CML CFU-GM comparably to effectors from 14 HLA-mismatched unrelated individuals (mean inhibition 42% +/- 9% vs 39.5% +/- 7% at a 10:1 effector-to-target (E/T) ratio), suggesting that killer inhibitory receptor (KIR) incompatibility was not essential for an antileukemic effect. Both CD56(+)CD3(-) (natural killer [NK]) and CD56(+)CD3(+)(NK-T) cells inhibited CFU-GM growth of CML but not normal CD34(+) cells. A mechanism for this leukemia-specific cytotoxicity was suggested by the abnormal overexpression of major histocompatibility class I chain-related gene A or gene B (MICA/B) on CML CD34 cells and their ability to bind the NK activation ligand NKG2D. However, in vivo, CML cells may avoid NK-cell-mediated immune destruction by immune escape, shedding MICA into the plasma, thereby down-regulating NKG2D on CML CD56(+) cells.

NK-KIR Transcript Kinetics Correlate With Acute Graft-Versus-Host Disease Occurrence After Allogeneic Bone Marrow Transplantation

Natural killer (NK) cell alloreactivity observed during stem cell transplantation (SCT) can be either beneficial (graft-versus-leukemia effect) or detrimental to the host (graft-versus-host disease). Killer immunoglobulin-like receptors (KIRs), expressed on NK and CD8 memory T cells, are regulated at a posttranscriptional level and, because there are currently no KIR-specific antibodies available, the analysis of these receptors remains elusive. To better define the role of cells expressing KIR after SCT, we studied KIR transcript repertoires in 29 grafted patients who received myeloablative or nonmyeloablative regimens. We restricted our analysis to 3DL1, 3DL2, 2DL4, 2DS3, and 2DS4 KIR transcripts 6 months after SCT. Absolute counts of NK and CD8 T cells were determined by flow cytometry, and KIR transcripts were quantified by real-time reverse transcription polymerase chain reaction at days 14, 28, 60, 100, and 180 after transplantation. Three groups of patients were identified. Groups I and III were characterized by the absence or a delayed appearance of KIR transcripts, which correlated with the highest risk of acute graft-versus-host disease (aGvHD). In contrast, in group II, a significant transcript peak was observed early, and only one patient suffered from aGvHD (p = 0.025). Thus determining the kinetics of KIR transcription should make it possible to identify transplanted patients at a high risk of developing aGvHD.

Expression of CD158b on Peripheral Blood Lymphocytic Cell After Kidney Transplantation

OBJECTIVE

To investigate the expression of CD158b on peripheral blood lymphocytes after kidney transplantation.

METHODS

Sixty two kidney transplant patients were divided into two groups (normal group and rejection group) according to pathologic results and clinical situation. Blood samples were assessed for percentage of CD3+; CD19+; CD3-CD16/56+; CD3+CD158b+; CD19+CD158b+, and CD3-CD16/56+CD158b+ subsets.

RESULTS

The percentages of CD3+ cells preop as well as at 1 and 7 postoperative and the day acute rejection happened were 60.06 +/- 4.67, 40.43 +/- 4.11, 31.67 +/- 4.04, and 39.21 +/- 5.20, respectively. The percentages of CD3-CD16/56+ were 21.65 +/- 1.79, 33.84 +/- 5.45, 38.10 +/- 4.86, and 39.53 +/- 4.80, respectively. The percentages of CD3+CD158b+ were 1.46 +/- 0.31, 1.88 +/- 0.70, 2.03 +/- 1.04, and 0.65 +/- 0.12, respectively. The percentages of CD3-CD16/56+CD158b+ were 5.87 +/- 1.24, 3.57 +/- 0.57, 2.82 +/- 0.45, and 1.60 +/- 0.33, respectively.

CONCLUSIONS

The percentage of CD3+ cells in the normal and the rejection groups decreased significantly. The percentages of CD158b+T cells decreased significantly after acute rejection. The percentage of CD158b+NK cells decreased significantly after kidney transplantation, decreasing gradually after acute rejection. The percentage of CD158b+ total T cells decreased significantly following acute rejection. The percentage of CD3-CD16/56+CD158b+ of total NK cells decreased significantly after kidney transplantation and after acute rejection. Because few factors interfere with the expression of CD158b on NK cells, monitoring of this marker may be accurate and sensitive.

The KIR gene family: life in the fast lane of evolution

A hallmark of human NK cells is the expression of HLA class I-specific killer-cell immunoglobulin-like receptors (KIR). An interesting facet of the KIR family is the unusual variability of the respective gene cluster, which is changing shape at an astonishing evolutionary pace. Not only do KIR genes come in different allelic variants, but the KIR locus has also gone through drastic contractions and expansions in recent evolutionary history, resulting in a wide variety of KIR haplotypes. A new study now reveals how an originally nonfunctional KIR pseudogene, KIR3DP1, is brought back to life in certain individuals via non-reciprocal recombination between two different KIR haplotypes. This Commentary outlines how the unique architecture of the KIR locus facilitates the generation of new KIR haplotypes and discusses the functional relevance of it.