HLA-C C1C2 heterozygosity may protect women bearing the killer immunoglobulin-like receptor AA genotype from spontaneous abortion.

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.

Does the KIR2DS5 gene protect from some human diseases?

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 non-small-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.

Killer immunoglobulin-like receptor ligand HLA-Bw4 protects against multiple sclerosis.

OBJECTIVE: Multiple sclerosis (MS) is a chronic inflammatory disease affecting the central nervous system. A human leukocyte antigen (HLA) class II association is well established (DRB1*1501-DQB1*0602), but more recently HLA class II-independent associations with HLA class I variants have also been reported. The HLA class I (HLA-A, -B, -C) molecules serve as ligands for both T-cell receptors and killer immunoglobulin-like receptors (KIRs). We investigated the HLA class I alleles defined by their KIR binding motifs and the KIR genes to evaluate whether these genes could influence MS susceptibility or severity, alone or in combination. METHODS: We typed Norwegian MS patients (n = 631) and controls (n = 555) for HLA-A, -B, -C and -DRB1 alleles as well as the presence or absence of genes encoding inhibitory (KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL5, KIR3DL1, KIR3DL2, KIR3DL3) and activating (KIR2DS1, KIR2DS2, KIR2DS3, KIR2DL4, KIR2DS4, KIR2DS5, KIR3DS1) KIRs. RESULTS: The frequency of the HLA-Bw4 specificity, which is the ligand for the inhibitory KIR3DL1, was significantly reduced in MS patients as compared with controls (41.4% vs 55.1%, p(uncorrected (uc)) = 4.6 x 10(-6)). Also after stratifying for known HLA class II associations, the HLA-Bw4 association was seen (p(uc) = 0.002). No significant differences in gene carrier frequencies of inhibitory and activating KIRs were observed. However, our data indicate that MS patients who carry the activating KIR2DS2 and the inhibitory KIR2DL2 genes have more severe disease than patients not carrying these genes. INTERPRETATION: Carriage of the ligand of the inhibitory KIR3DL1 receptor, HLA-Bw4, was found to protect against MS in an HLA-DRB1 independent manner.

Particular genetic variants of ligands for natural killer cell receptors may contribute to the HLA associated risk of primary sclerosing cholangitis.

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.

Identification of new MHC-restriction elements for presentation of the p210(BCR-ABL) fusion region to human cytotoxic T lymphocytes.

Chronic myelogenous leukemia (CML) is characterized by a t(9;22) translocation resulting in expression of BCR-ABL fusion oncoproteins which are unique to the leukemic cells, necessary for oncogenesis, and potentially immunogenic. We have previously shown that human dendritic cells transduced with an adeno-associated virus vector encoding the fusion region of the b3a2 splice variant (p210(b3a2)) of the BCR-ABL oncoprotein elicit specific T-cell responses in vitro. Two cytotoxic T lymphocyte (CTL) clones generated in this fashion displayed restriction with previously unreported HLA alleles. The first, T1/B9, was CD4(+) and restricted by DRB5*0101 (autologous) or DRB1*1101 (allogeneic). The minimum cytotoxic epitope (MCE) binding to DRB5*0101 for this clone was identified as FKQSSKALQ, overlapping the p210(b3a2) fusion point (boldface). The MCE of DRB1*1101 for this clone differed from DRB5*0101, but also included the fusion point. The clonality of CTL T1/B9 was verified by analyses of TCRalpha/beta chain usage and DNA sequence analyses. To our knowledge, this is the first description of a single clone recognizing both DRB5*0101 and DRB1*1101. The other CTL clone, T1/33, was CD8+ and recognized HLA-B*3501 or B*3503 complexed with an MCE, RPVASDFEP, derived from the c-abl sequence in proximity to the p210(b3a2) fusion point. K562 cells transfected with plasmids encoding HLA-DRA + B5*0101, B*3501, or B*3503 but not controls expressing DRA + DRB1*1501 were lysed by cognate CTL clones, confirming that DRB5*0101 and B*3501/3 could present p210(b3a2) joining region epitopes via endogenous processing. The identification of three additional HLA alleles (DRB5*0101, B*3501, and B*3503) presenting the p210(b3a2) fusion-region antigen will broaden the application of vaccine strategies for targeting CML cells. The findings of single CTL clones cross-recognizing autologous (DRB5*0101 or B*3501) and allogeneic (DRB1*1101 or B*3503) HLA alleles presenting BCR-ABL fusion-region epitopes implies the potential separation of graft-versus-leukemia from graft-versus-host effects.

Immunogenicity of a p210(BCR-ABL) fusion domain candidate DNA vaccine targeted to dendritic cells by a recombinant adeno-associated virus vector in vitro.

Chronic myelogenous leukemia (CML) is characterized by a t(9;22) translocation, which results in the expression of chimeric BCR-ABL fusion oncoproteins that are necessary for oncogenesis, unique to the leukemic clones, and represent enticing targets for immunotherapy. As a strategy for the immunotherapy of CML, we constructed a recombinant adeno-associated virus vector encoding the p210(BCR-ABL) b3a2 variant fusion region with flanking sequences (CWRBA) and used it to express the BCR-ABL fusion region within primary human dendritic cells (DCs), the most potent antigen-presenting cells currently known. Peripheral blood mononuclear cells from healthy donors were primed and restimulated in vitro with autologous DCs transduced with purified CWRBA, CWRAP (negative control), or pulsed with a peptide corresponding to the fusion domain (positive control). No specific responses were generated using DCs transduced with CWRAP. In contrast, CWRBA-transduced DCs primed autologous T cells in an antigen-specific, MHC-restricted fashion to levels comparable with the positive control. CWRBA-transduced DCs elicited both cytotoxic CD4+/Th1 and CD8+ responses, although the former were more readily detected in this system. Cytotoxicity against a tumor cell line endogenously expressing the p210(BCR-ABL) b3a2 variant fusion region was also demonstrable. In addition, HLA-DRB5(*)0101+DRA (DR2a) was identified as a new restriction element capable of presenting the b3a2 BCR-ABL fusion region epitope. Thus, the construct developed herein may serve as a candidate vaccine for gene-based antigen-specific immunotherapy of CML and may serve as a paradigm for the use of DCs transduced with recombinant adeno-associated virus vectors encoding multiepitope immunogens for vaccine development.