Killer Immunoglobulin-Like Receptor 2DS2 (KIR2DS2), KIR2DL2-HLA-C1, and KIR2DL3 as Genetic Markers for Stratifying the Risk of Cytomegalovirus Infection in Kidney Transplant Recipients

Platelet-derived major histocompatibility complex class I coating on Treponema pallidum attenuates natural killer cell lethality

The evasive tactics of Treponema pallidum pose a major challenge in combating and eradicating syphilis. Natural killer (NK) cells mediate important effector functions in the control of pathogenic infection, preferentially eliminating targets with low or no expression of major histocompatibility complex (MHC) class I. To clarify T. pallidum's mechanisms in evading NK-mediated immunosurveillance, experiments were performed to explore the cross-talk relations among T. pallidum, NK cells, and platelets. T. pallidum adhered to, activated, and promoted particle secretion of platelets. After preincubation with T. pallidum, platelets expressed and secreted high levels of MHC class I, subsequently transferring them to the surface of T. pallidum, potentially inducing an immune phenotype characterized by the "pseudo-expression" of MHC class I on the surface of T. pallidum (hereafter referred to a "pseudo-expression" of MHC class I). The polA mRNA assay showed that platelet-preincubated T. pallidum group exhibited a significantly higher copy number of polA transcript than the T. pallidum group. The survival rate of T. pallidum mirrored that of polA mRNA, indicating that preincubation of T. pallidum with platelets attenuated NK cell lethality. Platelets pseudo-expressed the MHC class I ligand on the T. pallidum surface, facilitating binding to killer cell immunoglobulin-like receptors with two immunoglobulin domains and long cytoplasmic tail 3 (KIR2DL3) on NK cells and initiating dephosphorylation of Vav1 and phosphorylation of Crk, ultimately attenuating NK cell lethality. Our findings elucidate the mechanism by which platelets transfer MHC class I to the T. pallidum surface to evade NK cell immune clearance.

The effects of killer cell immunoglobulin-like receptor (KIR) genes on susceptibility to severe COVID-19 in the Iranian population

BACKGROUND

Variations in the innate and adaptive immune response systems are linked to variations in the severity of COVID-19. Natural killer cell (NK) function is regulated by sophisticated receptor system including Killer-cell immunoglobulin-like receptor (KIR) family. We aimed to investigate the impact of possessing certain KIR genes and genotypes on COVID19 severity in Iranians. KIR genotyping was performed on 394 age/sex matched Iranians with no underlying conditions who developed mild and severe COVID- 19. The presence and/or absence of 11 KIR genes were determined using the PCR with sequence specific primers (PCR-SSP).

RESULTS

Patients with mild symptoms had higher frequency ofKIR2DS1 (p = 0.004) and KIR2DS2 (p = 0.017) genes compared to those with severe disease. While KIR3DL3 and deleted variant of KIR2DS4 occurred more frequently in patients who developed a severe form of the disease. In this study, a significant increase of and B haplotype was observed in the Mild group compared to the Severe group (respectively, p = 0.002 and p = 0.02). Also, the prevalence of haplotype A was significantly higher in the Severe group than in the Mild group (p = 0.02).

CONCLUSIONS

These results suggest that the KIR2DS1, KIR2DS, and B haplotype maybe have a protective effect against COVID-19 severity. The results also suggest the inhibitory gene KIR2DL3 and haplotype A are risk factors for the severity of COVID-19.

Molecular relapse monitoring reveals the domination of impaired NK cell education over impaired inhibition in missing KIR-ligand recognition in patients after unrelated hematopoietic stem cell transplantation for malignant diseases

Transplantation of HLA and/or KIR mismatched allogeneic hematopoietic stem cells can lead NK cells to different states of activation/inhibition or education/resetting and change anti-tumor immunosurveillance. In this study, we used molecular relapse monitoring to investigate a correlation between either missing ligand recognition or variation of the cognate iKIR-HLA pairs with clinical outcomes in patients with hematological malignancies requiring allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients (N = 418) with acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), myelodysplastic syndrome (MDS), or lymphoma receiving T-cell repleted graft from HLA-matched or partly mismatched unrelated donors between 2012 and 2020 in our center were included in this study. Missing-ligand recognition was assessed through the presence or absence of recipients' HLA ligand for a particular inhibitory KIR (iKIR) exhibited by the donor. Inhibitory KIR-HLA pair number variation was defined by loss or gain of a new cognate pair of HLA-KIR within the new HLA environment of the recipient, compared with the donor's one. Considering the results of our research, we drew the following conclusions: (i) loss of iKIR-HLA cognate pair for C1, C2, and/or Bw4 groups led to significant deterioration of disease-free survival (DFS), molecular relapse, overall survival (OS) and non-relapse mortality (NRM) for patients undergoing allo-HSCT in the standard phase of the disease. This phenomenon was not observed in patients who underwent transplantation in advanced hematological cancer. (ii) The missing ligand recognition had no impact if the proportion of HLA mismatches was not considered; however, adjustments of HLA mismatch level in the compared groups highlighted the adverse effect of the missing ligand constellation. (iii) The adverse effect of adjusted missing ligand suggests a predominance of lost NK cell education over lost NK cell inhibition in posttransplant recipients' new HLA environment. Our results suggested that donors with the loss of an iKIR-HLA cognate pair after transplantation should be avoided, and donors who provided an additional iKIR-HLA cognate pair should be preferred in the allo-HSCT donor selection process.

High-resolution characterization of KIR genes polymorphism in healthy subjects from the Bulgarian population-A pilot study

Although killer-cell immunoglobulin-like receptor (KIR) gene content has been widely studied in health and disease, with the advancement of next-generation sequencing (NGS) technology the high-resolution characterization of this complex gene region has become achievable. KIR allele-level diversity has lately been described across human populations. The present study aimed to analyze for the first time the allele-level polymorphism of nine KIR genes in 155 healthy, unrelated individuals from the Bulgarian population by applying NGS. The highest degree of polymorphism was detected for the KIR3DL3 gene with 40 observed alleles at five-digit resolution in total, 22 of which were common. On the other hand, the KIR3DS1 gene was found to have the lowest degree of polymorphism among the studied KIR genes with one common allele: KIR3DS1*01301 (31.6%). To better understand KIR allelic associations and patterns in Bulgarians, we have estimated the pairwise linkage disequilibrium (LD) for the 10 KIR loci, where KIR2DL3*00501 allele was found in strong LD with KIR2DL1*00101 (D' = 1.00, R2  = 0.742). This is the first study investigating KIR polymorphism at the allele level in a population from the South-East European region. Considering the effect of the populationally shaped KIR allelic polymorphism on NK cell function, this data could lead to a better understanding of the genetic heterogeneity of this region and can be carried into clinical practice by improvement of the strategies taken for NK-mediated diseases.

The role of immune checkpoints in antitumor response: a potential antitumor immunotherapy

Immunotherapy aims to stimulate the immune system to inhibit tumor growth or prevent metastases. Tumor cells primarily employ altered expression of human leukocyte antigen (HLA) as a mechanism to avoid immune recognition and antitumor immune response. The antitumor immune response is primarily mediated by CD8+ cytotoxic T cells (CTLs) and natural killer (NK) cells, which plays a key role in the overall anti-tumor immune response. It is crucial to comprehend the molecular events occurring during the activation and subsequent regulation of these cell populations. The interaction between antigenic peptides presented on HLA-I molecules and the T-cell receptor (TCR) constitutes the initial signal required for T cell activation. Once activated, in physiologic circumstances, immune checkpoint expression by T cells suppress T cell effector functions when the antigen is removed, to ensures the maintenance of self-tolerance, immune homeostasis, and prevention of autoimmunity. However, in cancer, the overexpression of these molecules represents a common method through which tumor cells evade immune surveillance. Numerous therapeutic antibodies have been developed to inhibit immune checkpoints, demonstrating antitumor activity with fewer side effects compared to traditional chemotherapy. Nevertheless, it's worth noting that many immune checkpoint expressions occur after T cell activation and consequently, altered HLA expression on tumor cells could diminish the clinical efficacy of these antibodies. This review provides an in-depth exploration of immune checkpoint molecules, their corresponding blocking antibodies, and their clinical applications.

The KIR repertoire of a West African chimpanzee population is characterized by limited gene, allele, and haplotype variation

Introduction

The killer cell immunoglobulin-like receptors (KIR) play a pivotal role in modulating the NK cell responses, for instance, through interaction with major histocompatibility complex (MHC) class I molecules. Both gene systems map to different chromosomes but co-evolved during evolution. The human KIR gene family is characterized by abundant allelic polymorphism and copy number variation. In contrast, our knowledge of the KIR repertoire in chimpanzees is limited to 39 reported alleles, with no available population data. Only three genomic KIR region configurations have been mapped, and seventeen additional ones were deduced by genotyping.

Methods

Previously, we documented that the chimpanzee MHC class I repertoire has been skewed due to an ancient selective sweep. To understand the depth of the sweep, we set out to determine the full-length KIR transcriptome - in our MHC characterized pedigreed West African chimpanzee cohort - using SMRT sequencing (PacBio). In addition, the genomic organization of 14 KIR haplotypes was characterized by applying a Cas9-mediated enrichment approach in concert with long-read sequencing by Oxford Nanopore Technologies.

Results

In the cohort, we discovered 35 undescribed and 15 already recorded Patr-KIR alleles, and a novel hybrid KIR gene. Some KIR transcripts are subject to evolutionary conserved alternative splicing events. A detailed insight on the KIR region dynamics (location and order of genes) was obtained, however, only five new KIR region configurations were detected. The population data allowed to investigate the distribution of the MHC-C1 and C2-epitope specificity of the inhibitory lineage III KIR repertoire, and appears to be skewed towards C2.

Discussion

Although the KIR region is known to evolve fast, as observed in other primate species, our overall conclusion is that the genomic architecture and repertoire in West African chimpanzees exhibit only limited to moderate levels of variation. Hence, the ancient selective sweep that affected the chimpanzee MHC class I region may also have impacted the KIR system.

Natural killer cells and their exosomes in viral infections and related therapeutic approaches: where are we?

Innate immunity is the first line of the host immune system to fight against infections. Natural killer cells are the innate immunity lymphocytes responsible for fighting against virus-infected and cancerous cells. They have various mechanisms to suppress viral infections. On the other hand, viruses have evolved to utilize different ways to evade NK cell-mediated responses. Viruses can balance the response by regulating the cytokine release pattern and changing the proportion of activating and inhibitory receptors on the surface of NK cells. Exosomes are a subtype of extracellular vesicles that are involved in intercellular communication. Most cell populations can release these nano-sized vesicles, and it was shown that these vesicles produce identical outcomes to the originating cell from which they are released. In recent years, the role of NK cell-derived exosomes in various diseases including viral infections has been highlighted, drawing attention to utilizing the therapeutic potential of these nanoparticles. In this article, the role of NK cells in various viral infections and the mechanisms used by viruses to evade these important immune system cells are initially examined. Subsequently, the role of NK cell exosomes in controlling various viral infections is discussed. Finally, the current position of these cells in the treatment of viral infections and the therapeutic potential of their exosomes are reviewed. Video Abstract.

Association of KIR genes polymorphism and its HLA ligands in Diffuse Large B-cell Lymphoma

INTRODUCTION

Non-Hodgkin lymphoma (NHL) is a heterogeneous disease, with each subtype associated with different risk factors. Within this group, diffuse large B-cell lymphoma (DLBCL) can be highlighted, the most common type of NHL.NK cells are key components of the innate immune response and may play an important antitumor role.

OBJECTIVE

The objective of the present work was to determine the polymorphism of KIR genes in Brazilian patients with DLBCL.

MATERIALS AND METHODS

Furthermore, we evaluated the association between the polymorphism of these genes and their ligands with the clinical course of the disease. For the study, 112 patients with DLBCL and 222 voluntary blood and bone marrow donors. The genetic material of these samples were extracted for KIR and HLA typing, determination of HLA ligands, determination of the KIR haplotype and search for the deletion of 22 bp in the KIR2DS4 gene. KIR genotype distributions were made by direct counting using 2 × 2 contingency tables using Fisher's exact test. The magnitude of the association was measured by odds ratio (OR) and 95% confidence interval. P values <.05 were considered significant. Overall survival and progression-free survival were assessed with a Kaplan-Meier estimator.

RESULTS

In the present study, an association of HLA-Bw4 and HLA-Bw480I ligand was found with more advanced stages of the disease. Also, an association of the KIR2DL3 gene with a better response to treatment was found.

CONCLUSION

With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment.Non-Hodgkin lymphoma (NHL) is a heterogeneous disease, with each subtype associated with different risk factors. Within this group, diffuse large B-cell lymphoma (DLBCL) can be highlighted, the most common type of NHL.NK cells are key components of the innate immune response and may play an important antitumor role. The objective of the present work was to determine the polymorphism of KIR genes in Brazilian patients with DLBCL. Furthermore, we evaluated the association between the polymorphism of these genes and their ligands with the clinical course of the disease. For the study, 112 patients with DLBCL and 222 voluntary blood and bone marrow donors. The genetic material of these samples were extracted for KIR and HLA typing, determination of HLA ligands, determination of the KIR haplotype and search for the deletion of 22 bp in the KIR2DS4 gene. KIR genotype distributions were made by direct counting using 2 × 2 contingency tables using Fisher's exact test. The magnitude of the association was measured by odds ratio (OR) and 95% confidence interval. P values <.05 were considered significant. Overall survival and progression-free survival were assessed with a Kaplan-Meier estimator. In the present study, an association of HLA-Bw4 and HLA-Bw480I ligand was found with more advanced stages of the disease. Also, an association of the KIR2DL3 gene with a better response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment was found. With this, we can conclude that the polymorphism of KIR genes and the association with HLA ligands can influence the prognosis of DLBCL, as well as the response to treatment.

KIR genotype and haplotype frequencies in the multi-ethnic population of Malaysia

Killer cell immunoglobulin-like receptors (KIR) genotype and haplotype frequencies have been reported to vary distinctly between populations, which in turn contributes to variation in the alloreactivity of natural killer (NK) cells. Utilizing the diverse KIR genes to identify suitable transplant donors would prove challenging in multi-ethnic countries, even more in resource-limited countries where KIR genotyping has not been established. In this study, we determined the KIR genotypes from 124 unrelated Malaysians consisting of the Malays, Chinese, Indians, and aboriginal people through polymerase chain reaction sequence-specific primer (PCR-SSP) genotyping and employing an expectation-maximization (EM) algorithm to assign haplotypes based on pre-established reference haplotypes. A total of 27 distinct KIR haplotypes were discerned with higher frequencies of haplotype A (55.2%) than haplotype B (44.8%). The most frequent haplotypes were cA01:tA01 (55.2%), cB01:tB01 (18.1%), and cB02:tA01 (13.3%), while the least frequent haplotypes were cB03:tB01 (1.2%), cB04:tB03 (0.4%), and cB03:tA01 (0.4%). Several haplotypes were identified to be unique to a specific ethnic group. The genotype with the highest frequency was genotype AB (71.8%), followed by AA (19.4%), and BB (8.9%). The Indians exhibited the lowest genotype AA but the highest genotype BB, whereas genotype BB was absent in the aboriginal people. Despite the limitations, the genotype and haplotypes in the Malaysian population were successfully highlighted. The identification of ethnic-specific KIR genotypes and haplotypes provides the first step to utilizing KIR in identifying suitable transplant donors to further improve the transplant outcome in the Malaysian population.

Risk factors for cytomegalovirus infection and disease after kidney transplantation: A meta-analysis

OBJECTIVE

To investigate the risk factors for cytomegalovirus (CMV) infection and disease in kidney transplantation recipient, and provide references for the prevention and control of CMV infection and disease in kidney transplantation patients.

METHODS

Chinese and international literature related to risk factors for CMV infection and disease in renal transplant recipients was searched using databases, including China National Knowledge Infrastructure; WanFang Data; Wiper; Chinese Biomedical Literature database; PubMed; Embase; Web of Science, and the Cochrane Register of Controlled Trials. Two researchers independently screened the literature, extracted the data, and evaluated the quality of the literature according to published standards. A meta-analysis was performed using RevMan 5.4 software to extract the risk factors for CMV infection and disease in renal transplant recipients.

RESULTS

A total of 59,847 subjects were included in 24 studies. The risk factors for CMV infection were ATG [OR = 2.76, 95% CI (2.10, 3.63), P < 0.00001], Donor (D) CMV-IgG(+) Receptor (R)(-): (D+/R-) [OR = 2.97, 95% CI (1.63, 5.44), P = 0.004 < 0.05], recipient age [OR = 1.96, 95% CI (1.50, 2.54), P < 0.00001], lymphocytopenia [OR = 3.26, 95% CI (1.46, 7.31), P < 0.00001], and mycophenolate [OR = 3.22, 95% CI (2.02, 5.46), P < 0.00001]. The protective factor for CMV infection was glomerular filtration rate (GFR) [OR = 0.98, 95% CI (0.97, 0.99), P < 0.00001], and the uncertain factors were the use of tacrolimus [OR = 0.91, 95% CI (0.64, 1.28), P = 0.58 > 0.05], rejection [OR = 1.32, 95% CI (0.49, 3.53), P = 0.58 > 0.05], donor age [OR = 1.00, 95% CI (0.99, 1.01), P = 0.67 > 0.5], and preemptive therapy [OR = 0.51, 95% CI (0.11, 2.36), P = 0.86 > 0.05]. The risk factors for CMV disease were D+/R- [OR = 4.78, 95% CI (3.76, 6.07), P < 0.00001], ATG [OR = 1.83, 95% CI (1.25, 2.67), P < 0.00001], rejection [OR = 1.42, 95% CI (1.26, 1.59), P < 0.00001], mycophenolate [OR = 1.67, 95% CI (1.38, 2.02), P < 0.00001], recipient age [OR = 1.03, 95% CI (1.02, 1.03), P < 0.00001], donor age [OR = 1.01, 95% CI (1.00, 1.01), P = 0.001 < 0.05], Donor (D) CMV-IgG(+) Receptor(R)(+): (D+/R+) [OR = 1.92, 95% CI (1.49, 2.46), P < 0.00001], the use of prednisolone [OR = 1.59, 95% CI (1.32, 1.92), P < 0.00001], and diabetes mellitus[OR = 1.18, 95% CI (1.01, 1.37), P = 0.03 < 0.05], and the uncertain factors were donor type [OR = 4.10, 95% CI (0.28, 59.79), P = 0.30 > 0.05], time of transplantation [OR = 0.95, 95% CI (0.78, 1.16), P = 0.64 > 0.05], and the use of cyclosporine [OR = 1.50, 95% CI (0.62, 3.64), P = 0.37 > 0.05].

CONCLUSION

There are many factors influencing CMV infection and disease in kidney transplant patients. Risk factors should be carefully monitored, protective factors strengthened, and more attention paid to uncertain factors.

Understanding Immune Responses to Viruses-Do Underlying Th1/Th2 Cell Biases Predict Outcome?

Emerging and re-emerging viral diseases have increased in number and geographical extent during the last decades. Examples include the current COVID-19 pandemic and the recent epidemics of the Chikungunya, Ebola, and Zika viruses. Immune responses to viruses have been well-characterised within the innate and adaptive immunity pathways with the outcome following viral infection predominantly attributed to properties of the virus and circumstances of the infection. Perhaps the belief that the immune system is often considered as a reactive component of host defence, springing into action when a threat is detected, has contributed to a poorer understanding of the inherent differences in an individual's immune system in the absence of any pathology. In this review, we focus on how these host factors (age, ethnicity, underlying pathologies) may skew the T helper cell response, thereby influencing the outcome following viral infection but also whether we can use these inherent biases to predict patients at risk of a deviant response and apply strategies to avoid or overcome them.

The Activating receptor KIR2DS2 bound to HLA-C1 reveals the novel recognition features of activating receptor

Killer cell immunoglobulin-like receptors (KIRs) are important receptors for regulating the killing of virus-infected or cancer cells of natural killer (NK) cells. KIR2DS2 can recognize peptides derived from hepatitis C virus (HCV) or global flaviviruses (such as dengue and Zika) presented by HLA-C*0102 to activate NK cells, and have shown promising results when used for cancer immunotherapy. Here, we present the complex structure of KIR2DS2 with HLA-C*0102 at a resolution of 2.5Å. Our structure reveals that KIR2DS2 can bind HLA-C*0102 and HLA-A*1101 in two different directions. Moreover, Tyr45 (in activating receptor KIR2DS2) and Phe45 (in inhibitory KIRs) distinguish the two different binding models and binding affinity between activating KIRs and inhibitory KIRs. The conserved "AT" motif of the peptide mediates recognition and determines the peptide specificity of recognition. These structural characteristic shed light on how KIRs activate NK cells and can provide a molecular basis for immunotherapy by NK cells.

KIR Receptors as Key Regulators of NK Cells Activity in Health and Disease

Natural killer (NK) cells are part of the cellular immune response. They target mainly cancer and virally infected cells. To a high extent cytotoxic activity of NK cells is regulated inter alia by signals from killer immunoglobulin-like receptors (KIR). The major histocompatibility complex (MHC) class I molecules are important ligands for KIR receptors. Binding of ligands (such as MHC I) to the KIR receptors has the important role in solid organ or hematopoietic cell transplantation. Of note, the understanding of the relationship between KIR and MHC receptors may contribute to the improvement of transplant results. Donor-recipient matching, which also includes the KIR typing, may improve monitoring, individualize the treatment and allow for predicting possible effects after transplantation, such as the graft-versus-leukemia effect (GvL) or viral re-infection. There are also less evident implications of KIR/MHC matching, such as with pregnancy and cancer. In this review, we present the most relevant literature reports on the importance of the KIR/MHC relationship on NK cell activity and hematopoietic stem cell transplantation (HSCT)/solid organ transplantation (SOT) effects, the risk of allograft rejection, protection against post-transplant cytomegalovirus (CMV) infection, pregnancy complications, cancer and adoptive therapy with NK cells.

HLA Class I Molecules as Immune Checkpoints for NK Cell Alloreactivity and Anti-Viral Immunity in Kidney Transplantation

Natural killer (NK) cells are innate lymphocytes that can kill diseased- or virally-infected cells, mediate antibody dependent cytotoxicity and produce type I immune-associated cytokines upon activation. NK cells also contribute to the allo-immune response upon kidney transplantation either by promoting allograft rejection through lysis of cells of the transplanted organ or by promoting alloreactive T cells. In addition, they protect against viral infections upon transplantation which may be especially relevant in patients receiving high dose immune suppression. NK cell activation is tightly regulated through the integrated balance of signaling via inhibitory- and activating receptors. HLA class I molecules are critical regulators of NK cell activation through the interaction with inhibitory- as well as activating NK cell receptors, hence, HLA molecules act as critical immune checkpoints for NK cells. In the current review, we evaluate how NK cell alloreactivity and anti-viral immunity are regulated by NK cell receptors belonging to the KIR family and interacting with classical HLA class I molecules, or by NKG2A/C and LILRB1/KIR2DL4 engaging non-classical HLA-E or -G. In addition, we provide an overview of the methods to determine genetic variation in these receptors and their HLA ligands.

Analysis of HLA haplotype and clinical factors during hematopoietic stem cell transplantation

BACKGROUND

The human leukocyte antigen (HLA) haplotype of the recipient in hematopoietic stem cell transplantation (HSCT) is a key factor in its success or failure. We analyzed the relationship between HLA haplotype frequency and associated clinical factors in HSCT patients.

METHODS

Patients who underwent allogeneic HSCT between 2000 and 2019 at our institution were enrolled in this study. The HSCT composition was 77 bone marrow transplantations (BMT), 38 peripheral blood stem cell transplantations (PBSCT), and 36 cord blood transplantations (CBT). Patients were classified into three groups according to their donor HLA haplotype frequency in the Japan Population: group A, top 1-10 haplotypes; group B, top 11-100 haplotypes; and group C, haplotype 101-. We then compared various items including clinical biomarkers with the HLA haplotype frequency.

RESULTS

A significant negative correlation was identified between older persons and length of survival. There are also significant correlations between survival and levels of immunoglobulin G, D-dimer, and C-reactive protein, as well as the platelet-large cell ratio before transplantation. A total of 96, 30, and 25 patients were classified into groups A, B, and C, respectively. The HSCT match rate was significantly higher in group A patients than in those of groups B and C. In contrast, the death rate, D-dimer level, and length of time for engraftment were significantly higher in group B and C patients than in those of group A.

CONCLUSION

An assessment of transplant-related complications is important in improving the performance of HSCT. The present data suggest that a special therapeutic strategy is necessary for HSCT using low-frequency HLA haplotypes.

Activating killer cell immunoglobulin-like receptors: Detection, function and therapeutic use

Killer cell immunoglobulin-like receptors (KIRs) have a central role in the control of natural killer (NK) cell function. The functions of the activating KIRs, as compared to those of the inhibitory KIR, have been more difficult to define due to difficulties in antibody-mediated identification and their apparent low affinities for HLA class I. Immunogenetic studies have shown associations of activating KIRs with the outcome of autoimmune diseases, pregnancy-associated disorders, infectious diseases and cancers. Activating KIR are thus thought to have important roles in the control of natural killer cell functions and their role in disease. In this review, we discuss current knowledge on activating KIR, their ligands and, their roles in the pathogenesis and potential therapy of human diseases.