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Endometriosis is defined as the presence of functional endometrial tissue outside the uterine cavity. Several hypotheses have attempted to explain the etiology and pathogenesis of endometriosis. Recently, it has been suggested that a defect of the natural killer (NK) activity in the recognition and lysis of endometrial cells is one of the crucial points in the development of this disease. Natural killer cells can express killer immunoglobulin-like receptors (KIR), which recognize class I human leukocyte antigens on target cells. We asked whether polymorphisms in KIR, HLA-C, and HLA-B genes are risk factors for endometriosis. We tested 153 women with endometriosis diagnosed on the basis of laparoscopic and histological examination, and 213 control healthy women, who gave birth to at least one child. The frequency of KIR genes in patients was similar to that in controls except for KIR2DS5, which exerted a protective effect only in HLA-C C2-positive individuals. Moreover, KIR2DS5-positive women with endometriosis had 13 times lower chance that the disease would occupy the peritoneum than KIR2DS5- and KIR2DS4del-negative ones (OR = 0.077, P = 0.0061). Similarly, KIR2DS4del-positive endometriotic persons had 11 times lower chance for peritoneal disease (OR = 0.094, P < 0.001). Negative linkage disequilibrium between KIR2DS5 and KIR2DS4del indicates that these genes are mutually exclusive. Our data suggest that KIR2DS5 may be associated with protection from endometriosis, whereas KIR2DS4del seems to be associated with higher disease stages, possibly by exclusion of protective KIR2DS5. [ABSTRACT FROM AUTHOR]

Background: KIR2DS5 gene encodes an activating natural killer cell receptor whose ligand is not known. It was recently reported to affect the outcome of hematopoietic stem cell transplantation. Methodology/Principal Findings: In our studies on KIR2DS5 gene associations with human diseases, we compared the frequencies of this gene in patients and relevant controls. Typing for KIR2DS5 gene was performed by either individual or multiplex polymerase chain reactions which, when compared in the same samples, gave concordant results. We noted an apparently protective effect of KIR2DS5 gene presence in several clinical conditions, but not in others. Namely, this effect was observed in ankylosing spondylitis (p = 0.003, odds ratio [OR] = 0.47, confidence interval [CI] = 0.28-0.79), endometriosis (p = 0.03, OR = 0.25, CI = 0.07-0.82) and acute rejection of kidney graft (p = 0.0056, OR = 0.44, CI = 0.24-0.80), but not in nonsmall- cell lung carcinoma, rheumatoid arthritis, spontaneous abortion, or leukemia (all p>0.05). In addition, the simultaneous presence of KIR2DS5 gene and HLA-C C1 allotype exhibited an even stronger protective effect on ankylosing spondylitis (p = 0.0003, OR = 0.35, CI = 0.19-0.65), whereas a lack of KIR2DS5 and the presence of the HLA-C C2 allotype was associated with ankylosing spondylitis (p = 0.0017, OR = 1.92, CI = 1.28-2.89), whereas a lack of KIR2DS5 and presence of C1 allotype was associated with rheumatoid arthritis (p = 0.005, OR = 1.47, CI = 1.13-1.92). The presence of both KIR2DS5 and C1 seemed to protect from acute kidney graft rejection (p = 0.017, OR = 0.47, CI = 0.25-0.89), whereas lack of KIR2DS5 and presence of C2 seemed to favor rejection (p = 0.0015, OR = 2.13, CI = 1.34-3.37). Conclusions/Significance: Our results suggest that KIR2DS5 may protect from endometriosis, ankylosing spondylitis, and acute rejection of kidney graft. [ABSTRACT FROM AUTHOR]

Primary human cytomegalovirus (HCMV) infection usually goes unnoticed, causing mild or no symptoms in immunocompetent individuals. However, some rare severe clinical cases have been reported without investigation of host immune responses or viral virulence. In the present study, we investigate for the first time phenotypic and functional features, together with gene expression profiles in immunocompetent adults experiencing a severe primary HCMV infection. Twenty primary HCMV-infected patients (PHIP) were enrolled, as well as 26 HCMVseronegative and 39 HCMV-seropositive healthy controls. PHIP had extensive lymphocytosis marked by massive expansion of natural killer (NK) and T cell compartments. Interestingly, PHIP mounted efficient innate and adaptive immune responses with a deep HCMV imprint, revealed mainly by the expansion of NKG2C+ NK cells, CD16+ V+2(γ) γδ T cells, and conventional HCMV-specific CD8+ T cells. The main effector lymphocytes were activated and displayed an early immune phenotype that developed toward a more mature differentiated status. We suggest that both massive lymphocytosis and excessive lymphocyte activation could contribute to massive cytokine production, known to mediate tissue damage observed in PHIP. Taken together, these findings bring new insights into the comprehensive understanding of immune mechanisms involved during primary HCMV infection in immunocompetent individuals. IMPORTANCE HCMV-specific immune responses have been extensively documented in immunocompromised patients and during in utero acquisition. While it usually goes unnoticed, some rare severe clinical cases of primary HCMV infection have been reported in immunocompetent patients. However, host immune responses or HCMV virulence in these patients has not so far been investigated. In the present study, we show massive expansion of NK and T cell compartments during the symptomatic stage of acute HCMV infection. The patients mounted efficient innate and adaptive immune responses with a deep HCMV imprint. The massive lymphocytosis could be the result of nonadapted or uncontrolled immune responses limiting the effectiveness of the specific responses mounted. Both massive lymphocytosis and excessive lymphocyte activation could contribute to massive cytokine production, known to mediate tissue damage. Furthermore, we cannot exclude a delayed immune response caused by immune escape established by HCMV strains. [ABSTRACT FROM AUTHOR]

Abstract: Atopic dermatitis (AD) is a common skin disease of complex etiology including affected humoral and cellular immune responses. The role of NK cells in development of this disease has been recently postulated, but is still poorly documented. The current study was undertaken to determine the impact of genes for the most polymorphic NK cell receptors, known as killer cell immunoglobulin-like receptors (KIRs), on the development of AD. We compared 240 patients suffering from AD with 570 healthy controls. Frequencies of the great majority of KIR genes did not differ between patients and controls, except for KIR2DS1, whose frequency was significantly (OR=0.629, CI95% (0.45; 0.87), p corr =0.0454) lower in patients than in controls. These results were confirmed in a second cohort of 201 patients. When both patient groups were combined and compared to the control group, the result for KIR2DS1 achieved even higher significance (OR=0.658, CI95% (0.5; 0.86), p corr =0.0158). To the best of our knowledge, this is the first report on KIR gene contribution to AD, and to allergy in general. [Copyright &y& Elsevier]

Abstract: The killer cell Ig-like receptor (KIR)–MHC class I pathway is an integral part of natural killer cell immunity, and its role in host protection from both cancer and infection is important. In addition, we have shown elevated KIR2DS2 and 2DS4 expression in PBMCs of patients undergoing hematopoietic cell transplantation (HCT) [1]. Since all inhibitory KIR promoters are known to be heavily methylated, the question asked here is how and when KIR2DS2 and 2DS4 promoters had changed their methylation profile in association with HCT. Genomic DNA, extracted from 20 KIR2DS2/4+ donor and recipient cells, was treated with sodium bisulfate that will modify the unmethylated cytosine into uracil. Sequencing chromatographs were examined for C/T double peak indicative of base conversion. A CpG island in KIR2DS2 promoter spans from −160 to +26 with six cytosine sites. In contrast, the KIR2DS4 promoter CpG island contains three cytosine sites. The noted increase of unmethylated sites was associated with increased KIR expression as measured by mRNA–cDNA Q-PCR. In addition, the frequency of unmethylated sites in the CpG island was increased after HCT. The mechanism through which hypomethylation occurs after HCT is not known but it suggests a linkage to NK clonal expansion during the process of NK education in response to transplant therapy or viral infection. [Copyright &y& Elsevier]

Abstract: Most human immunodeficiency virus (HIV) patients are seropositive for cytomegalovirus (CMV) but a smaller proportion experience end-organ disease. This observation may reflect variations in genes affecting inflammatory and natural killer cell responses. DNA samples were collected from 240 HIV-infected patients followed at the University Hospitals/Case Medical Center (Cleveland, OH) between 1993 and 2008. Seventy-eight patients (African Americans = 41, Caucasians = 37) experienced CMV disease. Genotypes were determined using allele-specific fluorescent probes or multiplex polymerase chain reaction sequence-specific primers. IL12B3′UTR*(1) and SLC11A1 D543N*(1,2) were associated with CMV disease in African American patients (p = 0.04 and p = 0.02, respectively). IL10-1082*(1,2) and LILRB1 I142T*(1) were associated with CMV disease in Caucasians (p = 0.02 and p = 0.07, respectively). DARC T-46C*(1) and CD14 C-159T*(2) were associated with low nadir CD4+ T cell counts in African American patients (p = 0.002 and p = 0.01, respectively). Caucasian patients carrying TNFA-308*2, TNFA-1031*(2), IL2-330*(1), CCL2-2518*(2), or LILRB1 I142T*(1) had significantly lower nadir CD4+ T cells in a bootstrapped multivariable model (p = 0.006–0.02). In general, polymorphisms associated with CMV disease and CD4+ T cell counts were distinct in Caucasian and African American patients in the United States. The LILRB1 I142T polymorphism was associated with both CMV disease and low nadir CD4+ T cell counts in Caucasians, but the clearest determinant of low nadir CD4+ T cell count in African American patients was DARC T-46C. [Copyright &y& Elsevier]

Abstract: Spontaneous abortion is the most common complication of human pregnancy. Natural killer (NK) cells expressing killer immunoglobulin-like receptors (KIRs), which may recognize HLA-C (i.e. its C1 or C2 groups) on trophoblast cells, constitute a large leukocyte population in the endometrium. This study investigated whether genetic polymorphisms in the KIR and HLA-C genes are risk factors for spontaneous abortion. One hundred and twenty-five couples with at least two spontaneous abortions, including eighty-five couples with idiopathic recurrent abortion (RSA; three or more abortions), and 117 control couples (with two or more healthy-born children) were tested. The frequencies of the individual KIR genes in the patients were similar to those in the controls. In the group of KIR AA women with HLA-C C2C2 partners, the HLA-C C1C2 heterozygotes were present in the controls but not in the patients (p =0.015 for all patients and p =0.0048 for RSA, but both comparisons lost significance after Bonferroni correction), whereas both homozygotes, C1C1 and C2C2, were absent in the control women but present among the aborting ones. Therefore, our results suggest that among KIR AA women who have HLA-C C2C2 partners, HLA-C heterozygous females show a trend towards an increased chance of successful pregnancy. [Copyright &y& Elsevier]

Abstract: Human T-lymphotropic virus 1 (HTLV-1)–associated myelopathy/tropical spastic paraparesis (HAM/TSP) affects approximately 5% of HTLV-1–infected individuals. It is poorly understood why only some infected subjects develop this disease, but host genetic factors may determine susceptibility. The innate immune system may influence disease outcome in HTLV-1–infected individuals because of its role in early immune responses to viral infections. Variation in genes encoding killer cell immunoglobulin-like receptors (KIR) and their human leukocyte antigen (HLA) molecule ligands may affect the risk of HAM/TSP. We performed a two-stage case-control study to examine the distribution of KIR genes and HLA-Cw groups in Peruvian HTLV-1–infected HAM/TSP individuals and asymptomatic carriers. We also tested for epistatic effects between specific KIR genes and HLA-Cw groups. In the first stage, we found several trends toward association with HAM/TSP or proviral load (PVL). However, these results were not replicated in the second stage. In conclusion, this is the first report on KIR gene frequencies in the Peruvian population and may be of significance in hematopoietic stem-cell transplants. Our study did not reveal significant associations between KIR genes and HLA-Cw groups and HAM/TSP or PVL. However, because our study was powered to detect only larger effects, additional studies using larger cohorts are needed. [Copyright &y& Elsevier]

Alloreactive NK cells lyse target cells lacking self-HLA-C or the HLA-B-Bw4 epitope. Prior to haploidentical stem cell transplants, donor alloreactivity toward the patient is evaluated by natural killer (NK) cloning followed by testing of the clones in the 51Cr-release assay. As only a few percent of NK clones are alloreactive, a large number of NK clones must be established and evaluated. This approach is laborious and time consuming, with a complete evaluation taking up to 6 weeks. We developed a flow cytometry-based cytotoxicity assay utilizing CD107a expression on 12-day polyclonally expanded NK cells and showed that NK alloreactivity mediated by inhibitory and activating KIR can be detected by measuring CD107a expression following incubation with targets lacking the appropriate class I epitope. The percentage of alloreactive NK cells varied greatly between individuals and was easily estimated by the CD107a assay. For each epitope (C1, C2, Bw4), donors were found who did not have alloreactivity, although alloreactivity was predicted by the current rules thought to govern alloreactivity. The data emphasize the importance of demonstrating alloreactivity in a functional assay. [Copyright &y& Elsevier]

Background/Aims: Combinations of killer immunoglobulin-like receptors (KIRs) and HLA class I ligands that reduce natural killer (NK) cell inhibition have been shown to increase risk for autoimmune diseases. We aimed to clarify to what extent such combinations influence susceptibility to primary sclerosing cholangitis (PSC). Methods: Three hundred and sixty-five Scandinavian PSC patients and 368 healthy controls were genotyped for the presence or absence of genes encoding all KIRs using a PCR-SSP approach. KIR binding site variation of HLA-A, -B and -C was also determined. Results: The KIR gene frequencies were similar among patients and controls. However, the frequency of HLA-Bw4 and -C2, which are ligands for the inhibitory KIRs 3DL1 and 2DL1, respectively, was significantly reduced in PSC patients as compared with controls (38.2% vs. 54.7%, P corrected[P c]=0.0006 and 42.7% vs. 56.9%, P c =0.009, respectively). Two HLA risk haplotypes in PSC (carrying DRB1*0301 or DRB1*1501, respectively) were devoid of both of these alleles, and carried the 5.1 variant of the major histocompatibility complex class I chain-related A (MICA) gene previously reported to influence PSC susceptibility. Conclusions: Particular variants of ligands for NK cell receptors encoded at three neighbouring genes in the HLA complex may contribute to PSC associations observed in this genetic region. [Copyright &y& Elsevier]

Abstract: In hematopoietic cell transplantation (HCT), natural killer cell alloreactivity conferred by inhibitory ligands of killer immunoglobulin-like receptors (iKIRLs) may result in beneficial or detrimental outcomes. More data may contribute to resolution of this complex issue. We analyzed 378 primary allogeneic transplants with T-replete grafts for acute lymphoblastic leukemia (n = 101), acute myeloid leukemia and myelodysplastic syndrome (n = 149), and chronic myeloid leukemia (n = 128). The cohort was divided into 3 groups: in group 1, HLA class I matched at the antigen level (n = 260); in group 2, HLA class I mismatched at the antigen level (n = 57); and in group 3, HLA class I and iKIRLs mismatched (n = 61). One-year overall survival (OS) across groups 1 (59%), 2 (49%), and 3 (30%) was significantly different (P = .002). In contrast to group 2, group 3 had statistically lower OS (P = .05) and event-free survival (P = .01). Relapse and relapse-free mortality appeared to contribute to the low OS in group 3. The detrimental effect of natural killer alloreactivity was also evident when HLA-matched transplants were analyzed for patients lacking iKIRLs. One-year OS in patients lacking the HLA-Cw group 1 or 2 iKIRL was significantly lower than that in patients having the iKIRLs (55% vs 67%, n = 246, P = .01). Our observations indicate that, in T-replete unrelated HCT, iKIRL mismatches and the absence of iKIRLs confer higher risk to patients after HCT. [Copyright &y& Elsevier]

• The incidence of AML relapse is reduced with CMV reactivation. • NK cells are involved in CMV-associated protection from AML relapse. • CMV infection trigger/enhance a response by NK expressing activating KIRs. Multiple retrospective studies have demonstrated an association between cytomegalovirus (CMV) reactivation and reduced risk of AML relapse. However, the potential mechanism explaining this association remains elusive. We investigated a homogeneous cohort of 288 adult patients with AML in remission who received allogeneic hematopoietic stem cell transplantation (HCT) from matched sibling/unrelated donors between 1995 and 2011. The 5-year cumulative incidence of relapse was greater in patients without CMV reactivation compared with those with reactivation (30.2% vs. 12.1%, p = 0.001) in a landmark analysis. In multivariate analyses CMV reactivation was independently associated with reduced relapse risk (HR: 0.49 [0.25-0.95], p = 0.036) and increased non-relapse mortality (26.5% vs. 13.1%, p = 0.002) resulting in similar 5-year overall survival (64.5% vs. 59.1%, p = 0.8). In further subgroup analyses the protective effect of CMV reactivation was significant in patients who received HCT from donors with KIR Bx compared to KIR AA (11.7% vs. 29.5%, p = 0.01). Likewise, the protective effect of CMV reactivation was more significant when the donors had 2DS1 activating KIR (11.5% vs. 30.7%, p = 0.05) compared with those without 2DS1 (14.3% vs. 27.5%, p = 0.12). Our data independently confirmed the association between CMV reactivation and AML relapse, suggesting the involvement of donor KIR genotypes and NK cell-mediated graft-versus-leukemia effect. [ABSTRACT FROM AUTHOR]

Aim NK cells have the ability to destroy leukemic cells when lacking the ligand for the corresponding inhibitory KIRs. It is documented, that a strong GVHD effect mediated by alloreactive NK cells, results in a reduced risk for relapse in acute myeloid leukemia, and it depends of the inhibitory and stimulatory signals mediated through their KIR ligands. We looked for KIR gene frequencies and haplotypes in ALL Mexican Mestizo children. Methods KIR and HLA genotyping was performed in 66 ALL patients and 357 controls, all of them, Mexican Mestizos. The presence of 14 KIR genes was detected using a PCR-SSP technique with four multiplex reactions. HLA typing was done using a Luminex PCR-SSOP method. Frequency (%) for KIR genes was determined by direct counting. Genotypes were assigned according to www.allelefrequencies.net. A and B haplotypes were deduced from the genotype data. The gene content and haplotype frequencies were compared between patients and controls, using the Chi 2 test with the SPSS17 software. Results We found a significant decrease of 2DS4 (54.5% vs. 72.8%; OR = 0.45; CI = 0.26–0.77; p = 0.003), 2DL2 (21.2% vs. 42.9%; OR = 0.36; CI = 0.19–0.67; p = 0.001), 2DS2 (19.7% vs. 44.8%; OR = 0.302; CI = 0.16–0.57; p < 0.001) and 2DS3 (7.6% vs. 24.4%; OR = 0.25; CI = 0.10–0.65; p = 0.001) in ALL children. Framework genes were present in all individuals (2DL4, 3DL2 and 3DL3). The frequency of AA genotype was significantly decreased in the cases vs. controls (31.9% vs. 45.5%; OR = 0.56; CI = 0.33–0.96; p = 0.03). Conclusions A low risk was shown for ALL, if carrying 2DS4, 2DL2, 2DS2 or 2DS3 in Mexicans. We also found that the AA haplotype is protective and contains the 2DS4 activating gene. Controversial results exist in ALL depending on ethnicity. In Canadians, a reduced risk exists when activating KIR genes are present, while in Germans no association was shown; AA was not associated in non-hispanics, while an increased risk was observed in Hispanics. Thus, it is crucial to analyze specific ethnic groups, since Hispanics include many different racial backgrounds. In our study, which is the first one done in Mexicans with ALL, only Mestizos were included. Our results are consistent with data demonstrating that KIR genes play an important role in disease survival. Therefore, more studies of KIR genes and ALL must be done in non-Caucasians. [ABSTRACT FROM AUTHOR]

Aim Receptor-ligand (KIR-HLA) interaction of natural killer (NK) cells with HLA antigens plays critical role in immune responses against viral infection and tumor transformation. Both gene families are highly polymorphic, their co-evolution and overall diversity is critical for population survival and reproduction. HLA class I antigens can be grouped as KIR ligands: A∗03, A∗11; HLA-A (Bw4), HLA-B (Bw4-I or T at position 80) and HLA-C (C1/C2), there are recognized by lineage II and III KIRs. Methods We estimate (Arlequin software) HLA Class I allele and haplotype frequencies for 3239 HSC transplant candidates at City of Hope typed during 2010–2014 at high resolution (SBT, SSO and/or Group-specific SSP). Results (Table): 75% of HLA-A and 64% of HLA-B lacks epitopes for KIR. Four main groups (A3/11, Bw4-A, Bw4-B-80I and Bw4-B-80T) binding KIR lineage II are distributed evenly (16–19% each). 50% of population is negative for any Bw4 haplotype, however, only 5% has both Bw4 (A/B). Majority of patients have C1 (62% allele frequency), however, their overall expression (frequency corrected by MFI coefficient as published in Science 2013) is similar to less frequent C2 group. In conclusion, HLA class I haplotypes have evolved to maximize interaction of KIR receptors. [ABSTRACT FROM AUTHOR]