KIR Genotype Research Articles

Role of Killer Immunoglobulin-like Receptor–Ligand Interactions in Human Leukocyte Antigen–Matched Sibling Hematopoietic Stem Cell Transplantation

IntroductionKiller immunoglobulin-like receptor (KIR)-ligand mismatches lead to natural killer cell alloreactivity after hematopoietic stem cell transplantation (HSCT). However, their clinical impact on HSCT outcomes is controversial due to complexity of KIR haplotypes, genotypes, and phenotypes as well as their diversity among patient populations. The present study investigated the role of KIR-ligand interactions in human leukocyte antigen (HLA)-matched sibling transplants. MethodsThe recipient cohort, which included patients diagnosed with aplastic anemia, acute leukemia, and myelodysplastic syndrome, received granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells. HLA typing was performed using polymerase chain reaction - sequence specific oligo probes (PCR-SSO). The KIR genotype of the donors and the ligands C1 (Asparagine 80), C2 (Lysine 80), and Bw4 recipient typings were performed using polymerase chain reaction - sequence specific primers (PCR-SSP). We assessed acute and chronic graft-versus-host disease (GVHD), relapse, and overall survival. ResultsWhile 84.5% of donors carried a Bx KIR, 15.5% carried the AA haplotype. The effect of a recipient's lack of ligands among 88.5% of cases was associated with 39% of subjects developing GvHD. Lack of C1 may lead to manifestations of acute GvHD and lack of C2 to manifestation of chronic GvHD. The presence of both C1 and C2 seemed to be protective against both forms of GvHD. The role of two Bw4 alleles, threonine (T) or isoleucine (I) at position 80, was evaluated. 73% of recipients who carried Bw4 80(I) versus 27% with the Bw4 80(T) allele. The presence of Bw4-80(T) allele appeared to reduce the risk of GvHD, indicating its stronger inhibitory effect than its 80(I) counterpart. ConclusionKIR-ligand interactions influenced HSCT outcomes.

Molecular monitoring of minimal residual disease in two patients with MLL-rearranged acute myeloid leukemia and haploidentical transplantation after relapse

This report describes the clinical courses of two acute myeloid leukemia patients. Both had MLL translocations, the first a t(10;11)(p11.2;q23) with MLL-AF10 and the second a t(11;19)(q23;p13.1) with MLL-ELL fusion. They achieved a clinical remission under conventional chemotherapy but relapsed shortly after end of therapy. Both had a history of invasive mycoses (one had possible pulmonary mycosis, one systemic candidiasis). Because no HLA-identical donor was available, a haploidentical transplantation was performed in both cases. Using a specially designed PCR method for the assessment of minimal residual disease (MRD), based on the quantitative detection of the individual chromosomal breakpoint in the MLL gene, both patients achieved complete and persistent molecular remission after transplantation. The immune reconstitution after transplantation is described in terms of total CD3+/CD4+, CD3+/CD8+, CD19+, and CD16+/CD56+ cell numbers over time. The KIR and HLA genotypes of donors and recipients are reported and the possibility of a KIR-mediated alloreactivity is discussed. This report illustrates that haploidentical transplantation may offer a chance of cure without chronic graft-versus-host disease in situations where no suitable HLA-identical donor is available even in a high-risk setting and shows the value of MRD monitoring in the pre- and posttransplant setting.

Association of Killer Cell Immunoglobulin–Like Receptor and Human Leukocyte Antigen-C Genotype with Dry Eye Disease in a Chinese Han Population

Dry eye is one of the most prevalent eye diseases and dry eye disease (DED) is associated with ocular surface inflammation. The interaction between killer cell immunoglobulin-like receptors (KIRs) and human leukocyte antigens (HLAs) regulates the activation of natural killer (NK) cells and certain T cell subsets in response to inflammation. The objective of this study was to explore whether KIR gene and HLA-C allele polymorphisms were associated with DED in a Chinese Han population. Polymerase chain reaction with sequence-specific primers method was used to genotype KIR genes and HLA-C alleles in 106 DED patients and 220 healthy controls. Framework genes KIR2DL4, KIR3DL2, KIR3DL3, and KIR3DP1 were present in all individuals. There were no significant differences in the frequencies of inhibitory KIR genes between the two groups. However, the frequency of KIR2DS2 was significantly higher in severe DED patients than that in healthy controls (p=0.031, odds ratio [OR]=1.828, 95% confidence interval [CI]=1.05-3.17). Significantly different distributions of HLA-C allele groups were not observed in severe DED patients and controls. The frequency of the combination of HLA-C1 allele group with KIR2DS2 was significantly higher in severe DED patients compared with controls (p=0.013, OR=2.083, 95% CI=1.16-3.74). These data suggested that this genotype combination was associated with susceptibility to severe DED and that NK cells might have a role in the pathogenesis of DED. The results led to an interesting future research question of whether or not KIR and HLA-C genotypes were involved in the predisposition to or pathogenesis of DED.

Pregnancy Close to the Edge: An Immunosuppressive Infiltrate in the Chorionic Plate of Placentas from Uncomplicated Egg Cell Donation

In pregnancies achieved after egg donation (ED) tolerance towards a completely allogeneic fetus is mediated by several complex immunoregulatory mechanisms, of which numerous aspects are still unknown. A distinct lesion not described previously in the literature, was repeatedly found in the chorionic plate in a substantial portion of placentas from ED pregnancies, but never in placentas from normal term pregnancies. The aim of this study was to assess its origin and its cellular composition. The relation between the lesion, the clinical and histological parameters were assessed. In addition we investigated the relation with the number of HLA-mismatches and KIR genotype of mother and child.In ten out of twenty-six (38.5%) placentas from ED pregnancies an inflammatory lesion was present in the chorionic plate. A significantly lower incidence of pre-eclampsia was found in the group with the lesion; 0% versus 45.5%. A significant relation was found between this lesion and the presence of intervillositis, chronic deciduitis, presence of plasma cells and fibrin deposition in the decidua. Fluorescent in situ hybridisation with X/Y-chromosome probes showed that the majority of cells present in the lesion are of maternal origin. The expression of the macrophage marker CD14+ and of the type 2 macrophage (M2) marker CD163+ was significantly higher in the lesion. The incidence of a fetal HLA-C2 genotype was significantly higher in cases with a lesion compared to the group without the lesion. In conclusion, a striking relationship was observed between the presence of a not previously described inflammatory lesion in the chorionic plate and the absence of pre-eclampsia in ED pregnancies. The lesion consists of mainly maternal cells with a higher expression of the macrophage marker CD14+ and the M2 marker CD163+. These findings suggest a protective immune mechanism which might contribute to the prevention of severe clinical complications like pre-eclampsia.

Associations of killer cell immunoglobulin- like receptor genes with rheumatoid arthritis.

Objective: Rheumatoid Arthritis (RA) is an autoimmune and chronic inflammatory disease of unknown etiology. Killer cell immunoglobulin-like receptors are expressed on the surface of natural killer cells and CD28null T-cells, both present in synovial membrane of RA. Therefore we evaluated the associations of KIR genes with RA. Methods: 16 KIR genes were genotyped in 100 healthy subjects (HS) and 100 RA patients from Western Mexico using PCR-SSP. Differences in KIR genotypes and gene frequencies were assessed using the X2 test. Results: Gene frequency of KIR2DL3 was lower in RA than in HS (p = 0.0019), whereas KIR2DL2 and KIR2DS2 were higher in RA than HS (p = 0.0004 and p = 0.0487, respectively). In addition were identified 38 genotypes (from G1-G38) in both studied groups, and the genotype frequencies of G1, G6 and G14 showed significant differences (p = 0.0001, p = 0.0208 and p = 0.0300, respectively). Conclusions: The presence of KIR2DL2, KIR2DS2 and absence of KIR2DL3 are associated with RA. Moreover, two genotypes BX are associated with RA. These results suggest that KIRs can be involved in RA susceptibility.

The Effect of KIRs Expression Profile in Donor/Recipient Pairs in HLA-Identical Sibling Hematopoietic Stem Cell Transplantation,

Abstract 4017 Objective:We investigated the distribution characteristics of KIRs expression profile in donor/recipient pairs with acute leukemia (AL) receiving HLA-identical sibling hematopoietic stem cell transplantation (sib-HSCT). We further explored the effect of KIRs expression profile in donor/recipient pairs on clinical outcome, including dynamics of donor T cell and NK cell engraftment. Methods:The genotypes of donor/recipient KIRs were determinated by polymerase chain reaction- sequence specific primer (PCR-SSP) for 80 pairs of donor/recipient receiving HLA-identical sibling hematopoietic stem cell transplantation. The multiple short tandem repeat (STR) PCR was used to evaluate the status of engraftment of donor T cells and NK cells at +14 days, 21 days, 28 days, 60 days and 90 days after transplantation in 24 cases. Results: 1.In 80 pairs of donor/recipient: (i) the KIRs were completely identical in 57.5% of donor/recipient pairs; (ii) the donors' KIRs contained the recipients' in 13.75% pairs; (iii) the recipients' KIRs contained the donors' in 17.5% of pairs; (iv) the KIRs were completely different in 11.25% pairs. The graft versus host (GVH) direction KIR-matched group was 75%. The percentage of group donor B/X and group donor A/A was 50%, respectively. 2. Comparing the patients from GVH direction KIR-matched and mismatched group, the incidence of acute (a) GVHD was 60% and 30%, respectively (P =0.0222), and 2-year OS was 62.96% and 94.12%, respectively (P =0.0492). Particularly, grade III-IV aGVHD rate of KIR-matched group was higher than that of non-KIR matched group(15% vs 0%). 3. Donor B/X group had a higher 2-year OS and 2-year relapse-free survival (RFS) compared with donor A/A group (89.23% vs 49.57%, P =0.0159, and 90% vs 59.71%, P =0.0239, respectively). Patients with three or less aKIRs had a lower 2-year OS (58.9% vs 92.44%, P =0.0338) and a lower RFS (65.14% vs 92.59%, P =0.0398), compared with patients with more aKIR. 4. Sequential monitoring of chimerism status of donor NK-cells in 24 cases revealed that on day+14, the percentage of full donor NK cells chimerism was higher in non-KIR matched patients than that of KIR matched patients (85.7% vs 52.9%, P =0.0456). Conclusions:Donor KIR genotype appears to have a direct impact on aGVHD, OS and RFS. Therefore, donor KIR genotype should be evaluated as an outcome predictor of the HLA-identical sib-HSCT. Disclosures:No relevant conflicts of interest to declare.

30-OR Influence of HLA class I and KIR genotypes on HIV-1 positive subjects from Rio Grande do Sul, Brazil

30-OR Influence of HLA class I and KIR genotypes on HIV-1 positive subjects from Rio Grande do Sul, Brazil

31-OR: KIR genotypes indicative of less inhibition but more activation are strongly associated with pulmonary tuberculosis (PTB)

31-OR: KIR genotypes indicative of less inhibition but more activation are strongly associated with pulmonary tuberculosis (PTB)

Genetic polymorphism analysis of killer cell immunoglobulin-like receptor genes in the Chinese Uygur population

Human killer cell immunoglobulin-like receptors are expressed in natural killer cells and subsets of T lymphocytes. They regulate these cells upon interaction with human leukocyte antigen class I molecules and other ligands presented by target cells. KIR gene frequencies and haplotype distributions have been shown to differ significantly between populations from different geographical regions and ethnic origins, which relates to functional variations in the immune response. We have investigated KIR gene frequencies and genotype diversities of 15 KIR genes (KIR2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 2DS1, 2DS2, 2DS3, 2DS4, ID, 2DS5, 3DL1, 3DL2, 3DL3, 3DS1) and two pseudogenes (KIR3DP1 and 2DP1) in 120 unrelated healthy individuals of the Uygur population living in the Xinjiang autonomous region of China. All individuals were typed positive for the four framework loci KIR3DL3, 2DL4, 3DL2 and KIR3DP1, while activating genes (KIR2DS1, 2DS2, 2DS3, 2DS5 and KIR3DS1) indicated some variation in this population. KIR3DS1 was found in a higher frequency in the studied population than in other groups from China. Linkage disequilibrium among KIR genes displayed a wide range. χ(2) analysis, conducted among non-ubiquitous genes, based on the KIR gene frequency data from our study population and previously published population data, revealed significant differences in the KIR2DL1, 2DL2, 2DL3, 2DL5, 3DL1, 2DS1, 2DS2, 2DS3, 2DS5, and 3DS1 genes. A neighbor-joining phylogenic tree, built using the observed carrier frequencies data of 13 KIR loci (KIR2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 3DL1, 3DL2, 3DL3, 2DS1, 2DS2, 2DS3, 2DS5, and 3DS1), showed relationships between the population studied and other previously reported populations. The present study can therefore be valuable for enriching the ethnical gene information resources of the KIR gene pool, for population origin studies and for KIR-related clinical practice.

Lack of KIR2DL4 gene in a fertile Caucasian woman

Killer cell immunoglobulin-like receptor (KIR2DL4) gene is present in virtually all humans. It encodes a receptor present on uterine and decidual natural killer (NK) cells and some peripheral blood NK cells. Its only known ligand is human leukocyte antigen-G molecule expressed on extravillous trophoblasts invading the decidua. Therefore, KIR2DL4 has been regarded as a molecule important for successful pregnancy. However, a multiparous woman from Africa, lacking KIR2DL4 gene, was described suggesting that this gene is not absolutely required for successful human reproduction. Here, we describe a Polish woman who delivered a child and who is not only lacking KIR2DL4 gene, but also possessing a KIR genotype virtually identical to that of the African woman mentioned above. Their genotypes are compared with few other KIR2DL4-negative genotypes and haplotypes described so far.

KIR/HLA-I mismatching and risk of relapse in paediatric patients undergoing non-haploidentical allogeneic haematopoietic stem cell transplantation

In HSCT setting, KIR-driven alloreactivity might be better predicted if the donor KIR genotype is considered in addition to the recipient HLA genotype. The prediction of NK cell alloreactivity relies on the missing ligand in the recipient, a scenario that can be found in HLA-identical and non-identical allotransplants. The aim of this study was to investigate at genetic level the prognostic impact of recipient HLA-I lacking for donor KIR on allotransplanted patients outcome. We analysed donors KIR genotype and HLA genotype of 60 paediatric patients who received related (n=15) or unrelated (n=45) transplantation. When patients were grouped based on the KIR gene type involved in the KIR/HLA-I mismatch, we did not observe any relapse in the group of patients characterized by mismatches involving only inhibitory KIR. On the contrary, all relapses were observed in patients showing at least one activating gene involved in the mismatch (p<0.05). Although the biological mechanism accounting for this putative genetic rule is still to be clarified, we suggest that a careful survey of KIR/HLA-I mismatching should be taken into account in the selection of donor in related and unrelated HSCT.

Donor KIR2DS1 and KIR3DS1 Are Associated With Improved Outcomes Following Unrelated Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia

Current concepts of NK alloreactivity are based on donor/recipient KIR ligand mismatching and on donor KIR genotype variants, while little is known about the role of specific activating KIR genes. Specifically, the importance of the telomeric KIR2DS1 and KIR3DS1genes, and the centromeric KIR2DS2 gene has not been studied in detail. We tested the hypothesis that individual donor activating KIR genes would influence the outcome of AML patients undergoing unrelated allogeneic HCT.

Donor selection for natural killer cell receptor genes leads to superior survival after unrelated transplantation for acute myelogenous leukemia

AbstractKiller-cell immunoglobulin-like receptor (KIR) genes form a diverse, immunogenetic system. Group A and B KIR haplotypes have distinctive centromeric (Cen) and telomeric (Tel) gene-content motifs. Aiming to develop a donor selection strategy to improve transplant outcome, we compared the contribution of these motifs to the clinical benefit conferred by B haplotype donors. We KIR genotyped donors from 1409 unrelated transplants for acute myelogenous leukemia (AML; n = 1086) and acute lymphoblastic leukemia (ALL; n = 323). Donor KIR genotype influenced transplantation outcome for AML but not ALL. Compared with A haplotype motifs, centromeric and telomeric B motifs both contributed to relapse protection and improved survival, but Cen-B homozygosity had the strongest independent effect. With Cen-B/B homozygous donors the cumulative incidence of relapse was 15.4% compared with 36.5% for Cen-A/A donors (relative risk of relapse 0.34; 95% confidence interval 0.2-0.57; P < .001). Overall, significantly reduced relapse was achieved with donors having 2 or more B gene-content motifs (relative risk 0.64; 95% confidence interval 0.48-0.86; P = .003) for both HLA-matched and mismatched transplants. KIR genotyping of several best HLA-matched potential unrelated donors should substantially increase the frequency of transplants by using grafts with favorable KIR gene content. Adopting this practice could result in superior disease-free survival for patients with AML.

Association of KIR2DS1 and KIR2DS3 with fatal outcome in Ebola virus infection

Zaïre ebolavirus (ZEBOV) infection rapidly outruns the host's immunity and leads to death within a week. Fatal cases have been associated with an aberrant innate, proinflammatory immune response followed by a suppressed adaptive response leading to the rapid depletion of peripheral NK cells and lymphocytes. A critical role for NK cells has been suggested but not elucidated. In this genetic study, we investigated the association of KIR genotype with disease outcome by comparing genotypes of a Gabonese control population, IgG+ contacts, survivors, and fatalities of ZEBOV infection. We showed that the activating KIR2DS1 and KIR2DS3 genes associate with fatal outcome in Ebola virus infection. In addition, this study brings supplemental evidence in favor of the specificity of the IgG+ contact population. The outcome of fulminating Ebola virus infection could depend in part on the host's inherited KIR gene repertoire. This supports a key role for KIRs in disease susceptibility to infections.

KIR Genotype and Risk for Developing Crohn's Disease in Canadian Children

KIR Genotype and Risk for Developing Crohn's Disease in Canadian Children

Selection of Donors with Favorable KIR B Genotypes for Unrelated Hematopoietic Cell Transplantation Results in Superior Relapse Protection and Better Relapse-Free Survival for Patients with AML.

Abstract 665Unrelated donor (URD) transplants from donors with KIR group B/x genotypes (vs. A/A) confer a significant relapse-free survival (RFS) benefit for patients with acute myeloid leukemia (AML) (RR: 0.70 [95% CI: 0.55-0.88]; P = .002; Blood 2009; 113[3]). This new analysis was designed to investigate the beneficial effect of KIR B donors and to develop a donor selection strategy to improve clinical outcomes after hematopoietic cell transplantation (HCT) for leukemia. Based on an analysis of 27 unique KIR haplotype sequences we identified common centromeric and telomeric gene content motifs. KIR A haplotypes contain a Cen-A motif (defined by the presence of the inhibitory KIR gene 2DL3) and a Tel-A motif (defined by the presence of the activating gene 2DS4). The B haplotypes were defined as containing Cen-B (presence of 2DS2 and/or 2DL2) and/or Tel-B (presence of 2DS1), with further subdivisions possible at the allelic level. Thus, based on gene content alone, donor KIR genotypes can be classified as homogyzous A/A or defined by the type (Cen-B or Tel-B) or number (0, 1, 2 or ≥3; B domain content score) of B domains. Multivariate models were used to evaluate the effect of donor KIR genotypes on clinical outcomes after URD transplants facilitated by the National Marrow Donor Program for AML (n=1086) and acute lymphoblastic leukemia (ALL: n=334) between 1988 and 2006. The improved RFS associated with donor KIR B genotypes (Cen-A/B, Cen-B/B, Tel-A/B or Tel-B/B) vs. KIR A genotypes (Cen-A/A or Tel-A/A) in AML was most evident in the 115 donors (10.6%) who were homogyzous for the Cen-B motif (RR 0.72 [95% CI 0.55-0.94]; p=0.014). Likewise, Cen-B/B donors conferred significant protection against relapse (RR 0.34 [95% CI 0.2-0.57]; p < 0.0001); with absolute relapse rates of only 10% (Cen-B/B) vs. ∼31% (A/A). Similarly, multivariate models demonstrated that compared to KIR A/A donors, donors with higher KIR B domain content scores resulted in improved RFS (2B motifs: (RR 0.78 [95% CI 0.63-0.95]; p=0.013; n=244) or ≥3 B motifs: (RR 0.76 [95% CI 0.57-1.02]; p=0.07; n=84) and less relapse (2B motifs: (RR 0.54 [95% CI 0.39-0.74]; p=0.0001) or ≥3 B motifs: (RR 0.45 [95% CI 0.27-0.74]; p=0.0017). Donor KIR genotype had no effect on rates of graft vs. host disease or treatment related mortality. Importantly, the use of KIR B donors of any type was not associated with any improvement in clinical outcomes for patients with ALL. These data suggest that AML blasts may be particularly sensitive to killing by NK cells and raises the possibility that activating genes present in the donor KIR B haplotypes may uniquely recognize ligands on AML blasts. The KIR B genotype effects were not affected by the degree of HLA matching. Therefore, these data support the consideration of KIR genotyping with HLA typing into the unrelated donor search criteria for patients with AML. To capture the benefit of Cen-B and/or higher B domain content scores we propose that the ∼30% of donors who have ≥2 B domains (includes all Cen-B/B donors) be given preference over donors with 0 or 1 KIR B domains. In this large retrospective dataset, assignment by that rule resulted in significant improvements in RFS (RR 0.80 [95% CI 0.68-0.94]; p=0.0063) and relapse (RR 0.53 [95% CI 0.41-0.69]; p<0.0001). A prospective trial to test this strategy is planned. Disclosures:No relevant conflicts of interest to declare.

Presence of the Killer Immunoglobulin-Like Gene KIR3DS1 Is Associated with Poor Progression Free and Overall Survival Following Autologous Stem Cell Transplantation in Patients with Myeloma.

Abstract 2840Poster Board II-816Multiple myeloma (MM) remains incurable with a median survival of 3–4 years. Despite high dose therapy and autologous stem cell transplant (ASCT) most patients relapse with median progression-free survival (PFS) of 2.5–4 years and overall survival (OS) of 4–5 years. Although allogeneic SCT (allo-SCT) is potentially curative due to a graft-versus-myeloma effect, its applicability is significantly limited by high transplant related mortality (TRM). Therefore, the identification of additional independent biological predictors of outcome is required in order to tailor therapy to disease. Natural killer (NK) cells provide first line defence against tumors. NK cells have been shown to recognize and kill myeloma cells both in the allogeneic and autologous settings and donor NK genotype has been shown to influence leukemia free survival following allo-SCT. The aim of this study was to investigate the impact of KIR genotype on event-free (EFS) and OS following ASCT for MM. We performed KIR genotyping on 190 patients with MM receiving a first autologous transplant. KIR genotype and haplotype frequencies were comparable to those published for normal controls. Factors found on univariate analysis to be associated with a shorter EFS included haplotype Bx (containing at least 1 of the KIR B haplotype-defining loci- KIR2DL5, 2DS1, 2DS2, 2DS3, 2DS5, or 3DS1) (median 547 vs 656 days, P = 0.036), ≥3 activating KIR genes (median 547 vs 615 days, P = 0.046), the presence of activating KIR genes KIR2DS1 and KIR3DS1 (median 456 vs 589 days, and 464 vs 619 days, P=0.045 and 0.01 respectively). Disease status at ASCT was the most highly predictive factor for EFS. In patients with good risk disease (CR or PR at ASCT) KIR3DS1 status was highly predictive for EFS 464 days (341–586) vs 731 days (599–862) (P = 0.003) and OS 807days (713-901) vs 967 (925-1009) (P=0.023). KIR3DS1 was not predictive in patients with poor risk disease (P=0.36). Of note KIR3DS1+ve patients were equally represented in good risk (CR and PR) and poor risk (refractory or relapsed) groups at ASCT (around 30% in both groups). Notably the median EFS for KIR3DS1+ good risk patients was not significantly different to poor risk disease patients (P = 0.061). ASCT outcome was then determined according to 3 main groups based on disease status and KIR3DS1 status; A: Good Risk, KIR3DS1-ve; B: Good Risk, KIRDS1+ ve; and C Poor risk (KIR3DS1+ve or -ve). The RR of relapse or death was 1.0, 1.9 (P=0.002, 95% CI 1.3-3.1), and 3.0 (P=0.0001, 95% CI 1.9-4.8) respectively. By multivariate analysis, after adjusting for the presence of adverse cytogenetics and serum albumin and β2m, the KIR3DS1 status and grouping remained highly predictive of poor EFS, RR of 1.0, 2.7 (P= 0.021, 95%CI 1.2-6.2) and 5.3 (P= < 0.0001, 95%CI 2.4-11.7) respectively. The prognostic value of KIR3DS1 however, was greatest in patients in whom the ligand for the corresponding inhibitory KIR3DL1, Bw4 was missing. KIR3DS1+ KIR3DL1+ HLA-Bw4 negative patients had significantly reduced median EFS of 400d (315-495) vs 615 (545-684) for all other patients (P=0.048). Again this was most striking in good risk patients. Patients who had the genotype KIR3DS1+ KIR3DL1+ HLA-Bw4 –ve had a significantly shorter EFS survival of 372 days compared to 509 days in KIR3DS1+KIR3DL1+HLA-Bw4+ patients and 793 days for KIR3DS1 negative individuals (P=0.004). In conclusion: Our data from 190 patients with MM suggests that KIR3DS1, a gene previously linked to an increase risk of progression to invasive cervical carcinoma, independently predicts for poor EFS and OS following ASCT. A significant proportion (30%) of patients who are defined as good risk at ASCT (CR and PR) are KIR3DS1+ve and have an EFS which is not significantly different from patients who have refractory/relapsed disease at ASCT. This effect of KIR3DS1 is more significant in the absence of HLA-Bw4, the ligand for the inhibitory receptor KIR3DL1. The mechanism for this is effect is unclear and we are currently performing functional studies to further understand these findings. Disclosures:Apperley:Novartis: Consultancy, Honoraria. Marin:Novartis: Consultancy, Research Funding.

Susceptibility to Crohn’s disease is mediated by KIR2DL2/KIR2DL3 heterozygosity and the HLA-C ligand

In the present study, we investigated the relationship between the KIR loci and the genes encoding their HLA ligands and genetic susceptibility to Crohn's disease (CD). Analyses of the interactions between KIR3DL1, KIR2DL1, KIR2DL2, and KIR2DL3 with their respective HLA ligands indicate that there is a protective effect for KIR2DL2 in the absence of its HLA ligand C1. Given that KIR2DL2 and KIR2DL3 segregate as alleles, we compared their genotypic distributions to expectations under Hardy-Weinberg Equilibrium (HWE) with regard to the HLA ligand C1 status. While all the genotypic distributions conform to expectations under HWE in controls, in C2 ligand homozygous cases there is significant deviation from HWE, with a reduction of KIR2DL2, KIR2DL3 heterozygotes. KIR2DL2, KIR2DL3 heterozygosity is the only genotypic combination that confers protection from CD. In addition to the protective effect (OR = 0.44, CI = 0.22-0.87; p = 0.018) observed in C2 ligand homozygotes, the KIR2DL2, KIR2DL3 genotype is predisposing (OR = 1.34, CI = 1.03-4.53; p = 0.031) in the presence of C1 ligand. A test for trend of HLA class I C ligand group genotypes with KIR2DL2, KIR2DL3 heterozygosity in cases and controls indicates that C1, C2 ligand group heterozygotes have an intermediate effect on predisposition. These results show for the first time that disease susceptibility may be related to heterozygosity at a specific KIR locus, and that HLA ligand genotype influences the relative effect of the KIR genotype.

Influence of activating and inhibitory killer immunoglobulin-like receptors on predisposition to recurrent miscarriages

Sir, We read with interest the paper from Faridi et al. (2009) ‘Influence of activating and inhibitory killer immunoglobulin-like receptors on predisposition to recurrent miscarriages’ published recently in Human Reproduction. This is one of many recent papers on this topic which have presented frustratingly conflicting results and conclusions. There have been reports of a lack of association of recurrent miscarriage with maternal KIR repertoire (Witt et al., 2004), a lack of inhibitory receptors (Varla-Leftheriota, 2005), a lack of activating receptors (Hiby et al., 2008; Hong et al., 2008) or related to an increase in the frequency of activating KIR (Wang et al., 2007). Of concern is the disparity in the findings in these studies with no consensus and increasing confusion. The reasons for this are likely to be as follows. The studies all have small numbers of patients that have used different selection criteria. To determine any influence of the highly polymorphic KIR genes in a heterogenous condition such as recurrent miscarriage, it is essential to strictly define the affected group. Only women with three or more first trimester miscarriages and no live births should be included. Investigations ruling out other possible causes should be undertaken (e.g. anti-phospholipid antibodies, thyroid disease, uterine anomalies etc.). The controls should be matched with regard to age and ethnicity and should all have had a normal first pregnancy with no history of preeclampsia or fetal growth restriction. There are large numbers of KIR haplotypes that differ in both gene content and allelic polymorphism at individual KIR loci. These have been categorized as KIR A or KIR B haplotypes based on the presence/absence of particular KIR genes, and it is essential that they are defined in the same way. A current working definition provided by the IPD KIR database being as follows; Group B haplotypes are characterized by one or more of the following genes: KIR2DL2, KIR2DL5, KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS5 and KIR3DS1. Conversely, Group A haplotypes are characterized by the absence of all these genes. The distinction between Group A and B haplotypes is a useful one, having potential biological and medical significance. Studies of populations worldwide have established that KIR gene frequencies and KIR genotype occurrence vary markedly among different ethnic groups (Middleton et al., 2008; Single et al., 2008). In view of the above considerations, there are several possible explanations for why this paper on recurrent miscarriage has conflicting findings. The patients and controls were carefully selected on the basis of their clinical characteristics but consisted of four different caste groups divided into 12 different populations. It is known that the KIR gene frequencies differ quite considerably in some of these groups, and this may have skewed their findings (Rajalingam et al., 2002; Kulkarni et al., 2008). Even though the authors have tried to match numerically the controls and affected women as closely as possible with such small numbers, bias is still likely to be introduced. There is also some concern because the KIR gene frequencies in the controls are very different from those previously published in a North Indian population (Rajalingam et al., 2002). This latter study was performed by an experienced KIR reference lab giving additional confidence in their findings. Genotyping for the very similar KIR genes, often employing a PCR–SSP method (as used in the Faridi et al. study), is not trivial. We suggest that in future each group should check their KIR typing in reference to controls provided by designated KIR reference laboratories. The UCLA International KIR Exchange Program (ude.alcu.tendem@CIUecivreStneilC) now used by some 60 typing laboratories worldwide provides such a source of DNA to help confirm the accuracy and reliability of the KIR typing method employed. Otherwise, experienced typing groups can be approached individually to check typing schemes through the exchange of DNA samples. We suggest that in future vigorous verification of such anonymized samples is performed on studies such as these, so clarification and not confusion about the role of KIR in recurrent miscarriage is possible.

Anti-leukemia activity of alloreactive NK cells in KIR ligand-mismatched haploidentical HSCT for pediatric patients: evaluation of the functional role of activating KIR and redefinition of inhibitory KIR specificity

AbstractWe analyzed 21 children with leukemia receiving haploidentical hematopoietic stem cell transplantation (haplo-HSCT) from killer immunoglobulin (Ig)–like receptors (KIR) ligand-mismatched donors. We showed that, in most transplantation patients, variable proportions of donor-derived alloreactive natural killer (NK) cells displaying anti-leukemia activity were generated and maintained even late after transplantation. This was assessed through analysis of donor KIR genotype, as well as through phenotypic and functional analyses of NK cells, both at the polyclonal and clonal level. Donor-derived KIR2DL1+ NK cells isolated from the recipient displayed the expected capability of selectively killing C1/C1 target cells, including patient leukemia blasts. Differently, KIR2DL2/3+ NK cells displayed poor alloreactivity against leukemia cells carrying human leukocyte antigen (HLA) alleles belonging to C2 group. Unexpectedly, this was due to recognition of C2 by KIR2DL2/3, as revealed by receptor blocking experiments and by binding assays of soluble KIR to HLA-C transfectants. Remarkably, however, C2/C2 leukemia blasts were killed by KIR2DL2/3+ (or by NKG2A+) NK cells that coexpressed KIR2DS1. This could be explained by the ability of KIR2DS1 to directly recognize C2 on leukemia cells. A role of the KIR2DS2 activating receptor in leukemia cell lysis could not be demonstrated. Altogether, these results may have important clinical implications for the selection of optimal donors for haplo-HSCT.