Efficient and accurate KIR and HLA genotyping with massively parallel sequencing data.

Killer cell immunoglobulin like receptor (KIR) genes and human leukocyte antigen (HLA) genes play important roles in innate and adaptive immunity. They are highly polymorphic and cannot be genotyped with standard variant calling pipelines. Compared with HLA genes, many KIR genes are similar to each other in sequences and may be absent in the chromosomes. Therefore, although many tools have been developed to genotype HLA genes using common sequencing data, none of them work for KIR genes. Even specialized KIR genotypers could not resolve all the KIR genes. Here we describe T1K, a novel computational method for the efficient and accurate inference of KIR or HLA alleles from RNA-seq, whole-genome sequencing, or whole-exome sequencing data. T1K jointly considers alleles across all genotyped genes, so it can reliably identify present genes and distinguish homologous genes, including the challenging KIR2DL5A/KIR2DL5B genes. This model also benefits HLA genotyping, where T1K achieves high accuracy in benchmarks. Moreover, T1K can call novel single-nucleotide variants and process single-cell data. Applying T1K to tumor single-cell RNA-seq data, we found that KIR2DL4 expression was enriched in tumor-specific CD8+ T cells. T1K may open the opportunity for HLA and KIR genotyping across various sequencing applications.

Association of KIR2DL5, KIR2DS5, and KIR2DS1 allelic variation and atopic dermatitis.

Natural killer cells (NK) have been associated with the pathophysiology of atopic dermatitis (AD). NK function is regulated by killer cell Ig-like receptor family (KIR) receptors that interact with HLA ligands. The study goal was to focus on allelic variation in genes KIR2DL5, KIR2DS5, and KIR2DS1 with respect to AD. This was a case-control study of individuals with (n = 313) and without (n = 176) AD. Associations were estimated using logistic regression. The prevalence of KIR2DL5 was 52.5% (95% CI 48.0,57.0), KIR2DS5 was 33.0% (28.8,37.3), and KIR2DS1 was 33.6% (29.4,38.0). The presence of the KIR2DL5*001:01 increased the odds of having AD by about 86% (odds ratio (OR): 1.86(1.23,2.82) p = 0.003). The risk for individuals homozygous for KIR2DL5*001:01 was even greater (OR: 2.16 (95% CI 1.31,3.53) p = 0.0023). The odds of having AD with KIR2DL5*001:01 was similar in Whites and Blacks. Allelic variation in KIR2DS5 and KIR2DS1 was not associated with AD. There is no known HLA binding ligand for KIR2DL5. The effect of KIR2DL5*001:01 increased in the presence of HLA-B*-21TT leader sequence (2.46(1.37,4.41) p = 0.0025) and the HLA-C2 ligand (2.07 (1.37,4.41, p = 0.000002). Our study shows an independent association of the KIR2DL5*001:01 with AD and is the first study to associate AD with KIR allelic variation.

Killer cell immunoglobulin-like receptor (KIR) gene contents: Are they associated with cervical cancer?

Killer cell immunoglobulin-like receptors (KIRs) are required for natural killer cell function against virus-infected cells or tumor cells. KIR gene content polymorphisms in Indian women with cervical cancer (CaCx) remain unexplored. Hence, we analyzed the frequencies of KIR genes, KIR haplotypes, and Bx subsets to draw their association with CaCx. The polymerase chain reaction-sequence-specific primer method was used for KIR genotyping in three groups of women: healthy controls (n = 114), women with human papillomavirus (HPV) infection (n = 70), and women with CaCx (n = 120). The results showed that the frequency of KIR2DS5 was significantly higher in women with CaCx compared to women with HPV infection (p = 0.02) and healthy controls (p = 0.01). Whereas the frequency of KIR2DL5B was significantly higher in healthy controls than in women with HPV infection (p = 0.02). The total number of activating KIR genes was higher in women with CaCx than in healthy controls (p = 0.006), indicating their positive association with CaCx. Moreover, the C4T4 subset was higher in women with CaCx than in women with HPV infection, though not significant. In conclusion, our findings highlight KIR2DS5, the C4T4 subset, and activating KIR genes are susceptible factors or positively associated with CaCx. Besides KIR2DL5B, this study also reported for the first time significantly high frequency of KIR2DL1 in healthy controls, indicating its possible protective association against CaCx. Further, significantly high frequency of KIR2DL3 observed in HPV-infected women might be also a promising biomarker for viral infections. Thus, the study confirms the association of KIR genes with cervical cancer in women with HPV infection.

KIR2DL5B and HLA DRB1*12 alleles seems to be associated with protection against HIV-1 in serodiscordant couples in Burkina Faso.

The human immunodeficiency virus (HIV) belongs to the Retroviridae family and remains a public health problem in sub-Saharan Africa. Recent reports from WHO have shown that 33 million people died from HIV infections. HIV is one of the most serious fatal human diseases of the 20th and 21st centuries. However, variations in genetic and immunological factors are associated with protection against HIV infection in uninfected people exposed to HIV. This is the case with naturals killers which play an important role in the progression or regression of HIV infection. The objective of this study is to characterize certain HLA (human leukocyte antigen) class II genes and KIR genes in HIV-1 serodiscordant couples in Burkina Faso. This study was carried out at Burkina Faso among nineteen (19) HIV-1 serodiscordant couples. Classical multiplex PCR (SSP-PCR) was used to characterize the presence or absence of the KIR genes and certain class II HLAs (DRB1*11 and DRB1*12). The characterization of the KIR and HLA genes DRB1*11, DRB1*12 in this study demonstrated that the inhibitor KIR2DL5B, would confer protection against HIV-1 infection in seronegative partners (odd ratio [OR] = 0.13 [0.02-0.72] and p = 0.029), and the HLA DRB1*12 allele was associated with protection against HIV-1 infection in seronegative partners (OR = 0.16 [0.03-0.77] and p = 0.038). AA and Bx haplotypes were not found to be associated with HIV-1 infection in serodiscordant couples. This study confirms the involvement of the KIR genes in viral pathologies such as HIV-1 infection. Future larger-scale studies may provide a better understanding of the molecular mechanism by which the KIR haplotype and combination of KIR/HLA are associated with protection against HIV infection.

KIR and HLA-C genes in male infertility.

PURPOSE: Approximately 50% of men reporting to clinics for assisted reproduction have abnormal sperm parameters; we therefore considered whether they differ from fertile males in terms of the frequency of KIR and HLA-C genes, suggesting the involvement of NK cells and some T cells in the inflammatory reaction that can occur in the testes, vas deferens, or epididymis. METHOD: We tested a total of 1064 men: 445 of them were patients who, together with their female partners, participated in in vitro fertilization (IVF), 298 men whose female partners suffered from recurrent spontaneous abortion. Three hundred twenty-one fertile men constituted the control group. KIRs were genotyped using KIR Ready Gene kits and HLA-C by PCR-SSP methods. RESULTS: We found differences in KIR gene frequencies between men who became fathers via natural conception and men who participated in in vitro fertilization for KIR2DL2 (p/pcorr. = 0.0015/0.035, OR = 1.61), KIR2DL5 gr.2 (p/pcorr. = 0.0023/0.05, OR = 1.64), KIR2DS2 (p/pcorr. = 0.0019/0.044, OR = 1.59), and KIR2DS3 (p/pcorr. = 0.0016/0.037, OR = 1.67). KIRs in Cen AA region were significantly overrepresented in fertile males than in IVF males (p/pcorr. = 0.0076/0.03, OR = 0.67), whereas Cen AB + Cen BB frequency was higher in IVF males than in fertile males (p/pcorr. = 0.0076/0.03, OR = 1.50). We also observed a limited association in KIR-HLA-C combinations. CONCLUSION: Fertile men differ in profile of KIR genes and KIR-HLA-C combinations from men participating in IVF.

Killer immunoglobulin-like receptor genotypes and chronic myeloid leukemia outcomes after imatinib cessation for treatment-free remission.

BACKGROUND: Natural Killer (NK) cells are innate lymphoid cells that can be cytotoxic toward a large panel of solid tumors and hematological malignancies including chronic myeloid leukemia (CML). Such a cytotoxicity depends on various receptors. Killer immunoglobulin-like receptors (KIR) belong to these receptors and are involved in maturation process, then in the activation abilities of NK cells. METHODS: We investigated the prognostic impact of the KIR2DL5B genotype in 240 CML patients included in two clinical trials investigating tyrosine kinase inhibitors (TKI) discontinuation: STIM and STIM2. RESULTS: After adjustment for standard risk factors in CML, we found that the inhibitory receptor KIR2DL5B-positive genotype was independently related to a delayed second deep molecular remission (HR 0.54, 95% CI [0.32-0.91], P = 0.02) after TKI rechallenge but not to time to first deep molecular remission or treatment-free remission rates. CONCLUSION: These results suggest that KIR2DL5B could carry a role in lymphocyte-mediated control of leukemic residual disease control in patient with CML relapse.

KIR2DS1, 2DS5, 3DS1 and KIR2DL5 are associated with the risk of head and neck squamous cell carcinoma in Iranians.

BACKGROUND: Activating and inhibitory KIR receptors (aKIR, iKIR) control the development and function of NK cells whose function alterations adjust the tumor microenvironment immunity. This research was conducted to determine the KIRs gene impact on genetic predisposition to Head and Neck Squamous Cell Carcinoma (HNSCC) in Iranians. METHODS: KIR genotyping using sequence-specific primers-polymerase chain reaction (SSP-PCR) method was performed to identify the presence of all 16 KIR genes in 285 HNSCC patients, including laryngeal, oral cavity and pharyngeal SCC and 273 controls (CNs). RESULTS: Comparison of KIRs gene frequency between HNSCC and CNs revealed a highly significant increase in KIR2DL5, 2DS1, 2DS5, 3DS1 and CxT4 genotype and a decrease in KIR2DS4 deleted variant and AA genotype carriers. A significant increase was noted in individuals withhigher iKIRs than aKIRs in HNSCC compared with CNs. Individuals with ≥4 iKIR and those with ≥5 aKIRs were significantly more common in HNSCC than CNs. 68distinct KIR genotypes were identified in 558 individuals. CONCLUSION: Our findings determined the detrimental impact of KIR2DS1, 2DS5, 3DS1, 2DL5 and CxT4 genotype as well as the protective impact of KIR2DS4del and AA genotype on genetic predisposition to HNSCC in Iranians.

The effect of killer cell immunoglobulin-like receptor genotype on outcome of hematopoietic stem cell transplantation from matched sibling.

The alloreactivity of natural killer (NK) cell after allogeneic hematopoietic stem cell transplantation (AHSCT) is regulated by the interaction between donor killer immunoglobulin-like receptors (KIRs) and recipient human leukocyte antigen (HLA)-class I molecules. The aim was to identify KIR genes, haplotypes and their HLA-class I ligands and to investigate their association with transplantation outcome. The study included 65 patient/donor pairs who received AHSCT from HLA-matched identical siblings. KIR genotyping was done for donors using reverse sequence specific oligonucleotide probes (rSSO) coupled with luminex technology, while HLA-C genotyping was performed in patients using rSSO strip assay. In multivariate analysis, KIR2DS4 was associated with significant reduced incidence of relapse (p = .002). A trend towards reduced incidence of relapse was also observed with more than two KIR B motifs (p = .09), whereas a significant increased relapse was associated with homozygous HLA-C2 ligand compared to combined C1/C2 and C1/C1 (p = .04). Activating KIR2DS3 was associated with rapid leukocyte engraftment (p = .02). While, KIR 2DL5 was associated with decreased CMV infection (p = .03) and better platelets engraftment (p = .05). KIR genes, haplotypes and HLA-C alleles have an impact on HSCT outcome. Better selection of donors with favorable KIR genotype can improve HLA-matched sibling HSCT outcome especially for AML patients.

HIV exposed seronegative (HESN) compared to HIV infected individuals have higher frequencies of telomeric Killer Immunoglobulin-like Receptor (KIR) B motifs; Contribution of KIR B motif encoded genes to NK cell responsiveness.

Previously, we showed that Killer Immunoglobulin-like Receptor (KIR)3DS1 homozygotes (hmz) are more frequent in HIV exposed seronegative (HESN) than in recently HIV infected (HIV+) individuals. KIR3DS1 encodes an activating Natural Killer (NK) cell receptor (NKR). The link between KIR genotype and HIV outcomes likely arises from the function that NK cells acquire through expression of particular NKRs. An initial screen of 97 HESN and 123 HIV+ subjects for the frequency of KIR region gene carriage observed between-group differences for several telomeric KIR region loci. In a larger set of up to 106 HESN and 439 HIV+ individuals, more HESN than HIV+ subjects were KIR3DS1 homozygotes, lacked a full length KIR2DS4 gene and carried the telomeric group B KIR haplotype motif, TB01. TB01 is characterized by the presence of KIR3DS1, KIR2DL5A, KIR2DS3/5 and KIR2DS1, in linkage disequilibrium with each other. We assessed which of the TB01 encoded KIR gene products contributed to NK cell responsiveness by stimulating NK cells from 8 HIV seronegative KIR3DS1 and TB01 motif homozygotes with 721.221 HLA null cells and evaluating the frequency of KIR3DS1+/-KIR2DL5+/-, KIR3DS1+/-KIR2DS1+/-, KIR3DS1+/-KIR2DS5+/- NK cells secreting IFN-γ and/or expressing CD107a. A higher frequency of NK cells expressing, versus not, KIR3DS1 responded to 721.221 stimulation. KIR2DL5A+, KIR2DS1+ and KIR2DS5+ NK cells did not contribute to 721.221 responses or modulate those by KIR3DS1+ NK cells. Thus, of the TB01 KIR gene products, only KIR3DS1 conferred responsiveness to HLA-null stimulation, demonstrating its ligation can activate ex vivo NK cells.

Human Leukocyte Antigen C*12:02:02 and Killer Immunoglobulin-Like Receptor 2DL5 are Distinctly Associated with Ankylosing Spondylitis in the Taiwanese.

Human leukocyte antigen (HLA) class I ligands and Killer immunoglobulin-like receptors (KIRs) regulate the cytolytic activity of natural killer (NK) cells and certain T cells. We examined their genetic predisposition to disease susceptibility and clinical phenotypes in Taiwanese ankylosing spondylitis (AS) patients. KIR genotyping and Human Leucocyte Antigen C (HLA-C) sequencing were performed in 653 Taiwanese AS patients and 952 healthy controls. KIR genotype distributions and HLA-C allele frequencies were compared in patients and controls and among patients with and without HLA-B27 positivity, early age onset and spinal syndesmophytes. HLA-C alleles were functionally characterized using 3D structural modelling with peptide simulation. This study discovered that the HLA-C*12:02:02 allele (43.42% vs. 3.31%; p < 0.00001 odds ratio (OR), 16.88; 95% confidence intervals (CI): 11.27-25.28) confers a strong risk for Taiwanese AS development. The 3D modelling results identified four unique amino acid polymorphisms, Ala73, Trp156, Arg219 and Met304, that may affect the function of the HLA-C*12:02:02 allele. KIR2DL5 (p = 0.0047; pFDR = 0.0423) and the KIR Bx haplotype (p = 0.0000275) were protective against Taiwanese AS, while KIR 2DS4/1D (22 base pair truncated deletion; p = 0.0044; pFDR = 0.1998) appeared to be a risk factor for it. KIR2DL5 combined with the HLA-C1/C2 heterozygous genotype showed a protective effect (AS 5.97% vs. normal 11.66%; p = 0.002; pFDR = 0.0127, OR, 0.48 95% CI: 0.33-0.70); in contrast, KIR 2DS4/1D combined with the HLA-C1C1 homozygous genotype (AS 45.33% vs. normal 35.92%; p = 0.002; pFDR = 0.0127, OR, 1.48 95% CI: 1.21-1.81) represented a risk factor for AS development. Our data suggested that interactions between KIRs and their cognate HLA-C ligands may contribute to the pathogenesis of AS.

KIR2DL5 mutation and loss underlies sporadic dermal neurofibroma pathogenesis and growth.

Dermal neurofibromas (DNFs) are benign peripheral nerve sheath tumors thought to originate from Schwann cell progenitors. These tumors represent one of the hallmarks of the neurofibromatosis type 1 (NF1) tumor predisposition syndrome, where they can number in the thousands. While NF1-DNFs arise due to mutations in the NF1 gene, the vast majority of DNFs occur sporadically (sp-DNFs), where the genetic etiology is currently unknown. Herein, we employed whole-exome sequencing of sp-DNFs to identify a recurrent mutation in the KIR2DL5 gene, which codes for a protein suppressor of natural killer (NK) cell activity. While the function of KIR2DL5 outside of the immune system is unknown, we identified a KIR2DL5N173D mutation in three of nine sp-DNFs, resulting in loss of KIR2DL5 protein expression. In contrast, two of these subjects had unrelated tumors, which retained KIR2DL5 protein expression. Moreover, loss of KIR2DL5 expression was demonstrated in 15 of 45 independently-identified sp-DNFs. Consistent with its potential role as a negative growth regulator important for neurofibroma maintenance, ectopic KIR2DL5N173D expression in normal human Schwann cells resulted in reduced KIR2DL5 expression and increased cell proliferation. Similarly, KIR2DL5 short hairpin RNA knockdown (KD) decreased KIR2DL5 protein levels and increased cell proliferation, as well as correlated with PDGFRß and downstream RAS/AKT/mTOR hyperactivation. Importantly, inhibition of PDGFRß or AKT/mTOR activity in KIR2DL5-KD human Schwann cells reduced proliferation to control levels. Collectively, these findings establish KIR2DL5 as a new Schwann cell growth regulator relevant to sp-DNF pathogenesis, which links sporadic and NF1-associated DNFs through RAS pathway hyperactivation.

Identification of the novel KIR2DL4*00503 allele from a southern Chinese Han individual.

The novel KIR2DL4*00503 allele differs from the closest allele 2DL4*00501 by a single synonymous mutation.

Killer-cell immunoglobulin-like receptors and cytomegalovirus reactivation during late pregnancy.

Human cytomegalovirus (CMV) represents an important public health concern as it is associated with severe morbidity and mortality in transplant recipients, HIV-infected individuals and pregnant women given the risk of congenital infection. Congenital CMV is a leading cause of neurological sequelae, developmental delay and birth defects worldwide. Cytomegalovirus can be transmitted to the foetus following maternal infection or reactivation. NK cells expressing killer-cell immunoglobulin-like receptors (KIR) are part of the innate immune system and the first line of defence against viral incursions. Previous reports have shown that KIR genes are associated with CMV infections in the post-transplant setting. In this study, we set out to determine whether a protective effect of KIR genes over CMV infection is seen in Mexican pregnant women. Cytomegalovirus infection was assessed through nucleic acid testing in 200 pregnant women and 600 healthy blood donors comprising the Mexican mestizo reference population. Killer-cell immunoglobulin-like receptors and HLA-C genotypes were obtained from 200 pregnant women and 300 reference samples using a comprehensive PCR-SSP approach. We observed statistically lower carrier frequencies of cB03|tA01 gene-content haplotype, of cB03 haplotype motif, of the KIR2DL5 + 2DS3/2DS5 gene pair and of KIR2DL5 amongst CMV-positive pregnant women in comparison with those CMV negative. None of these were associated with CMV status in the reference population. Logistic regression analysis revealed that the most important factor determining CMV status during third-trimester pregnancies was the KIR2DL5 + 2DS3/2DS5 gene pair (OR 0.376 (95%CI 0.174, 0.811, P = 0.013). Our results indicate that CMV-protective KIR gene associations described in Caucasoid populations are also present in the genetically distinct Mexican mestizo population. Our results suggest that certain KIR gene combinations provide protection against CMV infections occurring during late-term pregnancies, a finding of utmost epidemiological importance given its implication with congenital CMV infections.

The investigation of killer cell immunoglobulin-like receptor genotyping in patients with systemic lupus erytematosus and systemic sclerosis.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterised by the production of autoantibodies and the involvement of multiple organ systems. Systemic sclerosis (SSc) is another autoimmune disease that causes fibrosis. We will aim to analyse the role of killer cell immunoglobulin-like receptor (KIR) genotypes and their existence with the respective HLA ligands in patients with SLE and SSc. Forty-five SLE, 25 SSc and 40 healthy controls were included. We examined the presence/absence of KIR2DL1, 2DL2, 2DL3, 2DL4, 2DL5A, 2DL5B, 2DS1, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 3DL1, 3DL2, 3DL3, 3DS1, 2DP1, 3DP1 and their known HLA ligands. In the SLE group, the KIR2DL5, KIR2DL5B and KIR2DS3 genes were significantly more frequent, and KIR2DL3 gene was significantly less than in controls (p values <0.05). In SSc patients, the KIR2DS3 gene was more frequent than in controls (p = 0.032). The KIR2DL3 gene was detected more frequently in controls while KIR2DS3 gene was more frequent in the patient group when SLE and SSc patients were combined (p values < 0.05). The KIR2DS2/HLA-C and KIR2DS2/HLA-C combinations were significantly more in both SLE and SSc groups than in controls. The KIR2DL2 and KIR2DL5B genes were protective from neurologic involvement in SLE patients (p values <0.05). The variations of some KIR genes such as KIR2DL5, KIR2DL5B, KIR2DS3 and KIR2DL3 may have a role in the pathogenesis of SLE and SSc. Also, the presence of KIR2DL2 and KIR2DL5B may cause major organ involvement, like neurologic involvement, in SLE.

KIR2DL5B genotype predicts outcomes in CML patients treated with response-directed sequential imatinib/nilotinib strategy.

Killer immunoglobulin-like receptors (KIRs) on natural killer (NK) cells have been shown to predict for response in chronic phase-chronic myeloid leukemia (CP-CML) patients treated with tyrosine kinase inhibitors. We performed KIR genotyping in 148 newly diagnosed CP-CML patients treated with a novel sequential imatinib/nilotinib strategy aimed at achievement of optimal molecular responses at defined time points. We found the presence of KIR2DL5B to be associated with inferior transformation-free survival and event-free survival and an independent predictor of inferior major molecular response (BCR-ABL1 ≤0.1%) and molecular response 4.5 (BCR-ABL1 ≤0.0032%). This suggests a critical early role for NK cells in facilitating response to imatinib that cannot be overcome by subsequent intensification of therapy. KIR genotyping may add valuable prognostic information to future baseline predictive scoring systems in CP-CML patients and facilitate optimal frontline treatment selection.

Genetic diversity of the KIR/HLA system and susceptibility to hepatitis C virus-related diseases.

BACKGROUND: The variability in the association of host innate immune response to Hepatitis C virus (HCV) infection requires ruling out the possible role of host KIR and HLA genotypes in HCV-related disorders: therefore, we therefore explored the relationships between KIR/HLA genotypes and chronic HCV infection (CHC) as they relate to the risk of HCV-related hepatocarcinoma (HCC) or lymphoproliferative disease progression. METHODS AND FINDINGS: We analyzed data from 396 HCV-positive patients with CHC (n = 125), HCC (118), and lymphoproliferative diseases (153), and 501 HCV-negative patients. All were HIV and HBV negative. KIR-SSO was used to determine the KIR typing. KIR2DL5 and KIR2DS4 variants were performed using PCR and GeneScan analysis. HLA/class-I genotyping was performed using PCR-sequence-based typing. The interaction between the KIR gene and ligand HLA molecules was investigated. Differences in frequencies were estimated using Fisher's exact test, and Cochran-Armitage trend test. The non-random association of KIR alleles was estimated using the linkage disequilibrium test. We found an association of KIR2DS2/KIR2DL2 genes, with the HCV-related lymphoproliferative disorders. Furthermore, individuals with a HLA-Bw6 KIR3DL1+ combination of genes showed higher risk of developing lymphoma than cryoglobulinemia. KIR2DS3 gene was found to be the principal gene associated with chronic HCV infection, while a reduction of HLA-Bw4 + KIR3DS1+ was associated with an increased risk of developing HCC. CONCLUSIONS: Our data highlight a role of the innate-system in developing HCV-related disorders and specifically KIR2DS3 and KIR2D genes demonstrated an ability to direct HCV disease progression, and mainly towards lymphoproliferative disorders. Moreover the determination of KIR3D/HLA combination of genes direct the HCV progression towards a lymphoma rather than an hepatic disease. In this contest IFN-α therapy, a standard therapy for HCV-infection and lymphoproliferative diseases, known to be able to transiently enhance the cytotoxicity of NK-cells support the role of NK cells to counterstain HCV-related and lymphoproliferative diseases.

Killer immunoglobulin-like receptor gene repertoire influences viral load of primary human cytomegalovirus infection in renal transplant patients.

Killer cell immunoglobulin-like receptors (KIR) are highly polymorphic members of the immunoglobulin superfamily, which influence the response of natural killer cells and some T-lymphocyte subsets. Analysis of a cohort of previously human cytomegalovirus (HCMV)-negative patients, who developed primary HCMV infection following HCMV-positive renal transplant (n=76), revealed an increase in the frequency of KIR genes located on the telomeric region of B haplotypes (Tel B). The presence of Tel B in combination with the KIR ligand HLA-C2 was significantly more frequent in this subgroup. These genetic factors were associated with resistance to HCMV infection in a second cohort (n=65), where the Tel B genes KIR2DL5, -2DS1, 2DS5 and -3DS1 were all significantly associated with high viral loads. Furthermore, the KIR haplotype Tel A when in combination with the KIR ligand HLA-C1 was significantly protective against the development of severe infection. Our results suggest that KIR are a significant factor in the control of primary HCMV infection, and that determination of KIR gene repertoire may help in detection of renal transplant patients who were most at risk.

Killer-cell immunoglobulin-like receptors and falciparum malaria in southwest Nigeria.

Killer-cell immunoglobulin-like receptors (KIRs) are a group of natural killer cell receptors (NKRs) that regulate NK-cell-mediated production of interferon gamma (IFN-γ) in response to infection. These receptors have recently been suggested to influence the severity of clinical Plasmodium falciparum malaria infection. We examined the KIR locus in relation to malaria in children from southwest Nigeria. Sequence specific priming (SSP)-PCR was used to detect the KIR genes. The presence or absence of fifteen different KIR genes was determined in each individual and the proportions compared across 3 clinical groups; asymptomatic malaria, uncomplicated clinical malaria and severe clinical malaria. The genes KIR2DL5, KIR2DS3 and KIR2DS5 were present in a significantly higher proportion of individuals in the asymptomatic control group than in the malaria cases. Furthermore, KIR2DS3 and KIR2DS5 were present in a higher proportion of uncomplicated malaria cases than severe malaria cases. Carriage c-AB2 genotype (which comprises all centromeric KIR genes including KIR2DL5, KIR2DS3 and KIR2DS5) decreases with severity of the disease suggesting that the KIR AB profile might be associated with protection from severe malaria infection in this population in Nigeria.

Gene expression profiling of peripheral blood leukocytes shows consistent longitudinal downregulation of TOMM40 and upregulation of KIR2DL5A, PLOD1, and SLC2A8 among fast progressors in early Alzheimer's disease.

We previously reported TOMM40 was significantly down-regulated in whole blood of Alzheimer's disease (AD) subjects. In this study, we examined whole blood gene profiling differences over a one-year period comparing early AD subjects based on disease progression. 6-monthly assessments and blood sampling on 29 probable AD subjects compared with age- and gender-matched controls were performed. AD subjects with change in Clinical Dementia Rating-Sum of Boxes (CDR-SB) score of ≥2 points/year were classified as fast-progressors and those with CDR-SB change of <2 points/year were classified as slow-progressors. We found statistically significant upregulation in KIR2DL5A, SLC2A8, and PLOD1 for fast- (n = 8) compared with slow-progressors (n = 21) across the time-points. TOMM40 gene expression remained significantly lower in AD patients at all time-points compared to controls, supporting our previous findings. Our novel findings of specific gene expression differences between fast- and slow-progressors in combination with consistently lower TOMM40 expression, suggest their potential role as prognostic blood biomarkers to predict progression in early AD.

Killer-cell immunoglobulin-like receptors (KIR) in severe A (H1N1) 2009 influenza infections.

Introduction of a novel influenza virus into the human population leads to the occurrence of pandemic events, such as the one caused by pandemic influenza A (H1N1) 2009 virus. The severity of infections caused by this virus in young adults was greater than that observed in patients with seasonal influenza. Fatal cases have been associated with an abnormal innate, proinflammatory immune response. A critical role for natural killer cells during the initial responses to influenza infections has been suggested. In this study, we assessed the association of killer-cell immunoglobulin-like receptors (KIRs) with disease severity by comparing KIR gene content in patients with mild and severe pandemic influenza virus infections to a control group. We found that activator (KIR3DS1 and KIR2DS5) and inhibitory (KIR2DL5) genes, encoded in group B haplotypes containing the cB01, cB03 and tB01 motifs, are associated with severe pandemic influenza A (H1N1) 2009 infections. Better understanding of how genetic variability contributes to influenza virus pathogenesis may help to the development of immune intervention strategies aiming at controlling the severity of disease.