An allelic typing method for 2DS4 variant used in study of haplotypes of killer cell immunoglobulin-like receptor gene

NK cell defects: implication in acute myeloid leukemia

Acute Myeloid Leukemia (AML) is a complex disease with rapid progression and poor/unsatisfactory outcomes. In the past few years, the focus has been on developing newer therapies for AML; however, relapse remains a significant problem. Natural Killer cells have strong anti-tumor potential against AML. This NK-mediated cytotoxicity is often restricted by cellular defects caused by disease-associated mechanisms, which can lead to disease progression. A stark feature of AML is the low/no expression of the cognate HLA ligands for the activating KIR receptors, due to which these tumor cells evade NK-mediated lysis. Recently, different Natural Killer cell therapies have been implicated in treating AML, such as the adoptive NK cell transfer, Chimeric antigen receptor-modified NK (CAR-NK) cell therapy, antibodies, cytokine, and drug treatment. However, the data available is scarce, and the outcomes vary between different transplant settings and different types of leukemia. Moreover, remission achieved by some of these therapies is only for a short time. In this mini-review, we will discuss the role of NK cell defects in AML progression, particularly the expression of different cell surface markers, the available NK cell therapies, and the results from various preclinical and clinical trials.

Impact of donor KIRs and recipient KIR/HLA class I combinations on GVHD in patients with acute leukemia after HLA-matched sibling HSCT

In addition to T cells, NK cells can also participate in the outcome of hematopoietic stem cell transplantation (HSCT) mainly through the interaction between donor killer cell immunoglobulin-like receptors (KIRs) and recipient human leukocyte antigen (HLA) class I molecules. There is a risk of GVHD other than leukemia relapse after allogeneic HSCT that activation of donor NK cells in the absence of appropriate inhibitory ligands will be one of the reasons. To investigate the impact of donor KIRs and recipient KIR/HLA class I combinations on GVHD and leukemia relapse in patients with acute leukemia after HSCT, 100 patients with acute leukemia who received HSCT from their HLA-matched siblings were included in this study. Genotypes of 16 KIR genes and two 2DS4 variants (full length and deleted alleles), along with HLA-A/B genotypes, were determined by PCR-SSP. HLA-C genotyping was done with the SSO-Luminex method. Chimerism analysis was done using 16 short tandem repeats (STRs) to detect early leukemia relapse. Acute (a)GVHD occurred in 38 patients, and 16 of them died during the study. None of the recipients showed any sign of leukemia relapse after HSCT. Full donor chimerism was observed in all tested patients during the first year after HSCT. Our results also indicated an increased risk of aGVHD in AA recipients with the C2/Cx, Bw4⁺ (or A-Bw4⁺) or HLA-A3^-/A11^- genotypes who received HSCT from Bx donors. Our results showed that donor selection based on donor-recipient KIR genotypes and recipient HLA class I status can improve the outcome of HSCT.

Study on the association of the polymorphism of HLA-II gene with leukemia

We explored the association between the HLA-II gene polymorphisms and the occurrence of leukemia. For this study, we selected 53 patients with leukemia treated at Zhongnan Hospital of Wuhan University from February 2014 to September 2015 and 46 healthy patients as the control group. We used polymerase chain reaction with sequence specific primers for DNA typing which was carried out to analyze the patients HLA-A/B gene polymorphism. We also used enzyme-linked immunosorbent assay and western blotting method to measure the protein expression of different genotypes and activity. Compared to the control group, HLA-A04, B08 gene frequencies were significantly lower than those of HLA-A04, B08 gene frequencies of the observation group; results were statistically significant (χ²=16.28, P<0.05; χ²=16.47, P<0.05). However, in the control group, the frequency of HLA-A09 gene was significantly higher than that of the observation group; there was a significant difference between the two groups (χ²=15.28, P<0.05). Through the measurement of the protein expression levels of the different genotypes in the control group and the observation group, it was found that in the observation group, HLA-A04, B08 protein contents (4.6 and 3.2 µg/l) were significantly higher than those of the control group (0.13 and 0.1 µg/l). While the control group HLA-A09 genotype protein content (3.7 µg/l) was significantly higher than that of the observation group (0.2 µg/l); there were significant differences between both (P<0.05). Therefore, there is a significant correlation between HLA-II gene polymorphism and leukemia that is higher than HLA-A04 and B08 gene frequency and can help promote the occurrence of leukemia. The higher frequency of HLA-A09 gene can help to suppress the occurrence of leukemia.

[The role of different KIR haplotypes in haplo-identical hematopoietic stem cell transplantation]

OBJECTIVE

To investigate the role of different immunoglobulin- like receptor (KIR)haplotypes in haplo- identical hematopoietic stem cell transplantation (HSCT).

METHOD

Killer cell KIR genotyping was performed on 468 individuals from 156 unrelated families by PCR-SSP. A total of 624 KIR haplotypes from the parents were used for haplotype analysis. Ninety-two patients received haplo-identical HSCT from one of the parents.

RESULTS

The family study showed segregation of one A haplotype and at least 20 unique B haplotypes. The frequency of haplotype A was 72.92% (455/624). The most commonly observed haplotypes in group B were B1, B2, and B3, present at a frequency of 10.26%, 5.77%, and 4.48%, respectively. Compared to KIR gene matched donors (n=17), grafts from KIR gene mismatched donors (n= 14) had a positive effect on survival after haplo- identical HSCT for AML/MDS patients (OS: 88.2%vs 42.9%,P=0.015; RFS: 88.2%vs 35.7%,P=0.007). No effect was observed for ALL/NHL patients (OS: 76.0%vs 75.0%,P=0.727; RFS: 68.0%vs 65.0%,P=0.866). A significantly lower survival rate was observed for transplants from AA (n=52) and AB1/AB2 donors (n=15), compared to other group Bx donors (n=25) (OS: 53.3%vs 96.0%,P=0.017; RFS: 53.3%vs 92.0%,P=0.019). Meanwhile, the risk of relapse was much higher in AA group (n=52) compared to Bx group (n=40) (25.0%vs 5.0%,P=0.009). A higher risk of TRM was observed in AB1/AB2 group (P=0.012). In addition, transplant from donors carried Cen-B was associated with an increased survival compared with Cen-A homozygous donors (OS: 94.7%vs 68.5%,P=0.036; RFS: 89.5%vs 64.4%,P=0.045).

CONCLUSION

Overall, KIR genotyping and haplotype analyses should be useful for selection of the most optimal donors with favorable KIR gene grafts. KIR gene mismatch donors should be preferred for AML/MDS patients. Selecting donors carried Cen- B and avoiding the selection of donors of KIR genotype AA/AB1/AB2 was strongly advisable for haplo-identical HSCT.

KIR-HLA profiling shows presence of higher frequencies of strong inhibitory KIR-ligands among prognostically poor risk AML patients

The expression and interaction between killer cell immunoglobulin-like receptors (KIRs) and HLA are known to be associated with pathogenesis of diseases, including hematological malignancies. Presence of B haplotype KIR in donors is associated with a lower relapse risk for acute myeloid leukemia (AML) after hematopoietic stem cell transplants (HSCT). However, the association of KIR and HLA repertoire with disease development and other clinical features is not well studied for AML. In this study, 206 Chinese patients with AML were analyzed for their FAB subtypes, risk groups, and chemo-responsiveness to assess possible association with their KIR and HLA profile. The results revealed that a B-content score of 2 was significantly more prevalent in AML patients when compared to normal controls. Notably, there is also a differential frequency in the distribution of B haplotype KIR across distinct FAB subtypes, where the M3 subtype had significantly lower frequencies of B haplotype KIR compared to the M5 subtype (p < 0.05). In addition, the stronger inhibitory KIR ligands HLA-C2 and HLA-Bw4-80I were present in significantly higher frequencies in the prognostically "poor" risk group compared to those with "favourable" risk (p < 0.01). Taken together, these associations with clinical features of AML suggest a role of the KIR-HLA repertoire in the development and biological behavior of AML.

KIR diversity in three ethnic minority populations in China

BACKGROUND

Killer cell immunoglobulin-like receptors (KIRs) show extensive variation in genetic content and allelic polymorphi sms among different populations.

MATERIALS AND METHODS

We analyzed the distribution of KIR genes in the Tibetan ethnic minority of Lhasa city, the Uyghur and Kazakh ethnic minorities of Urumqi city populations in China. Genotyping of 16 KIR genes was tested in 479 randomly selected individuals using the multiple PCR-SSP method.

RESULTS

A total of 42 KIR genotypes were detected, of which, 29 were predicted to be AB genotypes, 12 were BB genotypes and one was AA genotypes. 27 KIR genotypes were identified in Kazakhs, 30 KIR genotypes were identified in Uyghurs and 20 KIR genotypes were identified in Tibetans. The predominant genotype 1(AA genotypes) occurred most frequently in Tibetans (52.7%, 118/224), Kazakhs (43.2%, 54/125) and Uyghurs (34.9%, 45/130). Not only the four framework genes were present in all individuals, but the pseudogene 2DP1 could also be detected in all Uyghur individuals. Tibetans were different from Kazakh and Uyghur groups in KIR genetic content and KIR allelic variation. Intriguingly, Tibetans (29.5%, 66/224) had lower frequencies of 2DS4-v when compared with Uyghurs (60.8%, 79/130) and Kazakh s (59.2%, 74/125). Uyghurs (25.4%, 33/130) displayed higher frequencies of Bx genotypes with C4Tx (absence of KIR3DS1-2DL5-2DS5-2DS1) than both Kazakhs (11.2%, 14/125) and Tibetans (3.6%, 8/224).

CONCLUSIONS

The study showed that profile of KIR genotypes in three ethnic minority populations in China displayed ethnic diversity. It could be valuable for enriching the ethnical information resources for KIR gene, as well as facilitating further research on KIR-related diseases.

Characterization of Killer cell immunoglobulin-like receptor (KIR) genotypes and haplotypes in Chinese Han population

We performed Killer cell immunoglobulin-like receptor (KIR) genotyping on 1271 individuals of Chinese Han origin including 102 families and 965 unrelated individuals. The families (with one child and both parents) were subjected for haplotype analysis. Forty-one different genotypes were identified. The frequencies of the KIR genotypes found in the family panel were confirmed by those found in the unrelated panel. The family study showed segregation of one A haplotype and at least 15 unique B haplotypes. The most commonly observed haplotypes in group B were B1, B2, and B3, present at a frequency of 10.05%, 6.62%, and 4.90%, respectively. On the basis of the combination of KIR genes, six centromeric and seven telomeric gene motifs have been identified. Motif cB02 was the most frequent haplotype B specific centromeric segment while tB01 was the most frequent haplotype B specific telomeric segment. The distinct distribution of KIR haplotypes in each population may reflect the history of directional and balancing selection of different races. The gene combinations of group A and B1/B2/B3 haplotype were the most frequent genotypes named as Bx1, Bx2, and Bx3, present at a frequency of 13.72%, 7.35%, and 4.41% in the family panel, and at a frequency of 15.86%, 10.15%, and 5.80% in the unrelated panel, respectively. Overall, this study showed the diversity of KIR haplotypes and genotypes in Chinese Han population and developed a criterion for distinguish KIR haplotypes/genotypes for the population. KIR genotyping and haplotype analysis should be useful for selection of the most optimum donor grafts with favorable KIR gene content for transplants.

Role of KIR genes and genotypes in susceptibility to or protection against hepatitis B virus infection in a Turkish cohort

BACKGROUND

Killer cell immunoglobulin-like receptors (KIRs) are a family of inhibitory and activating receptors expressed by natural killer (NK) cells and regulate NK cell activity in the innate response against viral infections. The aim of this study was to determine the possibility of KIR genes and genotypes as a candidate for susceptibility to or protection against chronic hepatitis B virus (HBV) infection or spontaneous remission of the infection in a Turkish cohort.

MATERIAL AND METHODS

The present study was carried out on 37 patients with chronic HBV infection, 36 patients in spontaneous remission of HBV infection, and 85 healthy subjects. Sequence-specific oligonucleotide probes analysis was used to investigate 16 KIR genes. All data were statistically analyzed by the Fisher exact test.

RESULTS

The rate of inhibitory KIR2DL3 (p=0.0) and 3DS1 (p=0.0) were higher in the healthy group than the group composed of chronic HBV patients and patients with spontaneous remission. There were no statistically significant differences between the rate of AA and Bx genotypes of chronic HBV patients and patients with spontaneous remission and the control group (p>0.05).

CONCLUSIONS

Our results suggest that KIR2DL3 and KIR3DS1 genes could be protector genes for HBV infection and they could be important immuno-genetic markers in determining antiviral immunity in the Turkish population.

KIR2DS4 allelic variants: Differential effects on in utero and intrapartum HIV-1 mother-to-child transmission

KIR2DS4 is the only activating gene within the A haplotype, and alleles of KIR2DS4 can encode either functional (KIR2DS4-f) or non-functional (KIR2DS4-v) variants. To establish the role of KIR2DS4 in the context of HIV-1 mother-to-child transmission, we KIR genotyped 145 HIV-1 non-transmitting mothers (NT) and their exposed uninfected infants (EU), and 72 HIV-1 transmitting mothers (TR) and their infected infants [intrapartum (IP), in utero (IU) or IU2 (an IU-enriched infected group)]. The frequency of KIR2DS4-v was significantly higher in IU2 infants compared to EU infants (P=0.022, OR=2.88); this association was more significant amongst AA haplotypes (P=0.004, OR=18.4). Possession of KIR2DS4-f in the mother with absence in the infant (M+I- discordance) was associated with a higher risk of IP transmission (P=0.005, OR=3.84); whilst in M-I+ discordance, infant possession of KIR2DS4-v was associated with increased risk of IU acquisition (P=0.002; OR=6.40). This study highlights the importance of KIR2DS4 in HIV-1 transmission/acquisition.

Genetic profile of KIR and HLA in southern Chinese Han population

KIR and their HLA ligands are encoded by two of the most diverse gene families in the human genome. The function of KIR on the NK cell is highly dependent on the normal expression of class I HLA on the target cell. Previous population studies in southern Chinese have been focused on the KIR framework genes and genotypes but little is known about the compound profiles of KIR/HLA. The present study examined 503 unrelated individuals from southern Chinese Han population for the polymorphism of KIR and class I HLA genes. All 16 KIR genes were detected in the study population and the four framework genes KIR3DL2, 3DL3, 3DP1, and 2DL4 were present in all individuals. Thirty unique KIR gene profiles were found reflecting a rather limited number of KIR haplotypes in this population. KIRAA1 was the most common profile observed in 54.7% of the samples. Among the AA1 individuals, 15.6% were homozygous for the deleted KIR2DS4. Haplotype A (74.8%) was more common than haplotype B (25.2%). HLA-C1 was a much more common ligand for 2D KIRs than C2. Bw4-80I, Bw4-80T, and the Bw4-bearing HLA-A alleles were detected at similar frequencies. The matched KIR+HLA pairs 2DL2/3+C1 (98.1%), 3DL1+Bw4 (73.3%), 3DL2+A3/11 (60.0%) were the most common ones whereas 3DS1+Bw4-80I was the least common (9.4%). A total of 193 unique compound profiles of KIR-HLA were identified in 480 informative individuals, 130 of the profiles being detected only once. The study provided a comprehensive analysis of the KIR/HLA profiles in southern Chinese in regards of the presence/absence of KIR genes, HLA ligands, matched KIR+HLA pairs, and KIR/HLA compound profiles. The results could help to better understand the role played by KIR/HLA interaction in associated diseases and clinical transplantation in southern Chinese.

Killer cell immunoglobulin-like receptor genes in patients with breast cancer

Killer cell immunoglobulin-like receptors (KIRs) contribute to the pathogenesis of diverse kind of diseases. Previous studies have shown associations between KIR genes, their ligands and either protection or susceptibility to leukemias or virally associated solid tumors. However, the possible roles of KIR gene polymorphisms in the development of breast cancer remain largely unknown. To investigate the association of KIR gene polymorphisms with breast cancer, we carried out the present study on 33 breast cancer patients and 77 healthy controls by means of sequence-specific oligonucleotide probes analysis, and then all data were statistically analyzed by Fisher exact test. Our results showed that the frame genes KIR2DL4, 3DL2, 3DL3, and 3DP1 were found in all patients and all controls. The rate of activating KIR2DS1 was much higher in patients with breast cancer than that in healthy controls (P = 0.032) while the allelic types of activating 2DS4 (2DS4 003/4/6/7) were lower in patients with breast cancer compared with healthy controls (P = 0.028). Additionally, there was a statistically significant negative correlation between 2DL1 genes and breast cancer development (P = 0.025). In conclusion, this study suggests that the activating KIR2DS1 may trigger breast cancer development, while 2DL1 gene and 2DS4 003/4/6/7 alleles are possibly protectors for breast cancer.