Effect of low-level laser therapy on orthodontic dental alignment: a systematic review and meta-analysis.

The aim of this study is to systematically summarize the available evidence regarding low-level laser therapy (LLLT) speed-up effect on dental alignment in comprehensive orthodontic treatment. An extensive electronic search was conducted in PubMed, ScienceDirect, Cochrane, Web of Science, and Scopus up to February 20, 2023. The Cochrane risk of bias tool and the Newcastle-Ottawa Quality Assessment Form were used by two authors independently to assess the risk of bias (RoB). Statistical analysis was performed by Review Manager 5.3. The eight eligible trials were reviewed and included in qualitative synthesis. Four studies reported the overall time of leveling and alignment (OLAT, days), enabling a synthesizing of the data. The meta-analysis results showed that LLLT significantly reduced the overall time of leveling and alignment compared to control group (MD=-30.36, 95% CI range -41.50 to -19.22, P<0.0001), with moderate heterogeneity (χ2=4.10, P=0.25, I2=27%). Based on the data available, statistically significant evidence with moderate risk of bias suggests that LLLT may have a positive effect on accelerating dental alignment. However, due to the differences in intervention strategy and evaluating method, the conclusions should be interpreted with caution.

Effects of low-level laser therapy on orthodontic miniscrew stability: a systematic review.

BACKGROUND: Miniscrews as auxiliary anchorage devices in orthodontic treatment have definite advantages and efficacy. The aim of the present study was to investigate the scientific evidence including randomized controlled trials (RCTs) or controlled clinical trials (CCTs) to support the application of low-level laser therapy to improve miniscrews stability in orthodontic treatment. METHODS: An extensive literature research was conducted with the Cochrane Library, PubMed, EMBASE, Web of Science and ScienceDirect without language limitations. All searches were inclusive until June 2020. The Cochrane Risk of Bias Tool was used to assess the risk of bias (RoB) in the included RCTs. RESULTS: Through the electronic searches, 428 titles and abstracts were identified. From these, 4 articles were retrieved for review, and 3 of these met the inclusion criteria. Two RCTs reported increased miniscrews stability with low-intensity laser therapy, but the other one reported no difference. Except one study assessed as "high risk of bias" the other two were rated as "low risk of bias". CONCLUSION: There is insufficient evidence to support or refute the effectiveness of LLLT for improvement of miniscrew stability. Further studies with a better study design, reliable evaluation method, comprehensive evaluation intervals and appropriate loading protocol are required to provide more reliable evidence for the clinical application of LLLT.

Effects Of Triptolide On Tooth Movement And Root Resorption In Rats.

PURPOSE: The aim of this study was to investigate the effects of triptolide on the tooth movement and root resorption in rats during orthodontic treatment. MATERIAL AND METHODS: A total of 48 male Wistar rats were divided into three groups of 16 each. The right maxillary first molars of rats were drawn mesially by closed coil nickel-titanium spring with a force of 50 g. The two experimental groups received intraperitoneal injections of triptolide for 14 days at a dose of 15 µg/kg/day and 30 µg/kg/day, respectively. The control group received vehicle injections. After 14 days, the rats were humanely killed. The amount of tooth movement was measured. Eight rats from each group were randomly chosen for analysis of the percentage of root resorption area by scanning electron microscopy. For the remaining eight rats in each group, the H&E staining, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemistry analysis were performed. RESULTS: The amount of tooth movement and the ratio of root resorption area were significantly decreased in the triptolide-treated rats. The number of TRAP-positive cells was significantly lower in triptolide-treated groups. Moreover, the expression of nuclear factor kappa B ligand (RANKL) was reduced. In contrast, the expression of osteoprotegerin was significantly up-regulated. In the tension side, the expressions of runt-related transcription factor 2 and osteocalcin were significantly enhanced by triptolide injection. CONCLUSION: Triptolide injection could arrest orthodontic tooth movement and reduce root resorption in rats via inhibition of osteoclastogenesis. In addition, triptolide may exert a positive effect on osteoblastogenesis.

Muscone Promotes The Adipogenic Differentiation Of Human Gingival Mesenchymal Stem Cells By Inhibiting The Wnt/ß-Catenin Signaling Pathway.

OBJECTIVES: This study was performed to evaluate the effects of muscone on the proliferation, migration and differentiation of human gingival mesenchymal stem cells (GMSCs) and to explore the relevant mechanisms. MATERIALS AND METHODS: We performed studies to determine the effects and mechanisms of muscone on GMSC proliferation, migration and differentiation. We conducted CCK-8, colony formation, transwell chamber, scratch wound, alkaline phosphatase (ALP) staining and activity, and alizarin red and oil red O staining assays, as well as real-time quantitative polymerase chain reaction (qRT-PCR), to ascertain the effects of muscone on GMSC proliferation, migration and differentiation in vitro. The mechanism by which muscone influences the osteogenic and adipogenic differentiation of GMSCs was elucidated by qRT-PCR and Western blotting. RESULTS: We found that muscone significantly promoted GMSC proliferation, chemotaxis, wound healing and fat droplet formation and inhibited ALP activity and mineral deposition. Notably, we observed that the Wnt/ß-catenin pathway was closely related to the ability of muscone to inhibit the osteogenic differentiation and promote the adipogenic differentiation of GMSCs. The effect of muscone on the multidirectional differentiation capacity of GMSCs was significantly reversed by the agonist lithium chloride through the Wnt/ß-catenin signaling pathway. CONCLUSION: Muscone effectively increased the proliferation and migration, promoted the adipogenic differentiation and inhibited the osteogenic differentiation of GMSCs by inhibiting the Wnt/ß-catenin signaling pathway. These results may provide a theoretical basis for the application of GMSCs and muscone in tissue engineering and regenerative medicine.

Erythropoietin enhances osteogenic differentiation of human periodontal ligament stem cells via Wnt/ß-catenin signaling pathway.

OBJECTIVES: The aim of this study is to examine the roles of erythropoietin (EPO) in regulating proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and analyze the underlying signaling of these processes. MATERIALS AND METHODS: PDLSCs were isolated and characterized. The PDLSCs were transfected with ß-catenin shRNA. qRT-PCR and Western blot analysis were used to examine the osteogenic effects of EPO on the expression of osteogenic-related genes and protein (Runx2, OCN and Osterix) in PDLSCs. Alizarin Red-S staining was used to detect mineralized nodule formation. In addition, the relationship between the Wnt/ß-catenin pathway and the effect of EPO on the osteogenesis of PDLSCs was investigated. RESULTS: The results suggested that EPO exerts positive osteogenic effects on PDLSCs. The results showed that EPO decreased the growth of PDLSCs slightly and increased alkaline phosphatase activity and calcium deposition in a dose-dependent manner. The expression of Runx2, Osterix and OCN was increased after EPO administration. EPO increases ß-catenin and Cyclin D1 in PDLSCs. After transfected with ß-catenin shRNA, the osteogenic effect of EPO on PDLSCs was attenuated. CONCLUSION: EPO promotes osteogenic differentiation of PDLSCs. The underlying mechanism may be activating Wnt/ß-catenin signaling pathway.

Erythropoietin attenuates high glucose-induced oxidative stress and inhibition of osteogenic differentiation in periodontal ligament stem cell (PDLSCs).

Diabetes mellitus and periodontitis have long been considered to be biologically linked. Erythropoietin (EPO) has multiple biological functions, such as stimulating the proliferation and differentiation of erythroid progenitor cells and reducing glucose-induced oxidative stress via different mechanisms, acting as a direct antioxidant. The purposes of the study to examine the anti-oxidative effect of EPO on reducing high glucose-induced oxidative stress of hPDLSCs and provide a better understanding of the mechanism of these processes. PDLSCs were induced by highglucose (HG, 30 mM) in the presence or absence of EPO. Cell proliferation was measured by MTT assay. The reactiveoxygen species (ROS) level, malondialdehyde (MDA) level and superoxide dismutase (SOD) activity were detected to evaluate oxidative stress. qRT-PCR and western blot analysis were used to examine the expression of osteogenic related genes and protein (Runx2 and Osterix). Alizarin Red-S staining was used to detect mineralized nodule formation. The results showed that EPO promote the proliferation of PDLSCs, which was suppressed by high glucose (30 mM). Moreover, EPO attenuated high glucose (30 mM) induced oxidative stress by reducing the levels of ROS and MDA, and increasing the SOD activity. Furthermore,EPO alleviate high glucose(30 mM) induced suppression of osteogenic differentiation ability in PDLSCs, as evidenced by the up-regulated mRNA and protein expression of Runx2 and Osterix and increased ALP activity. In conclusion, EPO attenuates high glucose-induced oxidative stress, inhibitory effect of proliferation and inhibition of osteogenic differentiation in periodontal ligament stem cell (PDLSCs).

Novel strategy of sirolimus plus thymalfasin and huaier granule on tumor recurrence of hepatocellular carcinoma beyond the UCSF criteria following liver transplantation: A single center experience.

Although liver transplantation (LT) lengthens the survival time of patients with hepatocellular carcinoma (HCC), LT patients exhibit a high recurrence rate; particularly those that had advanced HCC associated with the tumor biological characteristics and long-term application of immunosuppressants. A consensus on optimal prophylaxis and treatment for recurrent HCC following LT does not currently exist. The present study retrospectively analyzed data from 36 non-University of California at San Francisco criteria-eligible patients with advanced HCC who underwent LT, and then treated them with sirolimus (SRL)-based therapy with thymalfasin and huaier granules (SRL+, n=18), or with tacrolimus-based therapy (controls; n=18). The SRL+ group had significantly longer recurrence times (P=0.008) and survival times (P<0.0001) (OS, 1-year: 100%, 3-year: 94.4%, 5-year: 77.8%; DFS, 1-year: 88.9%, 3-year: 55.6%, 5-year: 50.0%). Furthermore, compared with pre-LT values and the control group, the SRL+ group had significantly lower serum α-fetoprotein (AFP) levels (both P<0.0001) and percentage of Forkhead box P3 (FoxP3)+ Treg lymphocytes (P<0.001) during the first year. In the SRL+ group, FoxP3+/cluster of differentiation (CD)8+ Treg lymphocyte percentages decreased significantly following LT (P<0.001); however, CD8+/CD3+ T-cells significantly increased (P<0.001). Levels of serum AFP and FoxP3+ Treg cells increased when tumors relapsed, and decreased to near-normal when relapse foci were cured or stabilized. SRL+ therapy may decrease AFP and Treg levels, while increasing CD8+ T cells, indicating an associated mechanism among them. In conclusion, SRL+ therapy appears to be safe and effective in preventing HCC recurrence following LT with no significant adverse events, and warrants further investigation.

[Influence of fixed orthodontic treatment on oral health-related quality of life in adolescent and adult: a comparative study].

PROPOSE: To compare the changes in oral health-related quality of life(OHRQoL) among adolescent patients and adult patients during orthodontic treatment. METHODS: The clinical data were collected from 81 patients (aged 15 to 25 years old) who underwent comprehensive orthodontic treatment. The participants were divided into 2 groups: adolescent patients (n=43) and adult patients (n=38) by age. OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14). All subjects were examined and interviewed at baseline and the end of 3 stages during orthodontics treatment. Friedman 2-way analysis of variance (ANOVA) and Wilcoxon signed rank tests were used to compare the relative changes of OHRQoL among different time points with SPSS 20.0 software package. RESULTS: The scores of OHIP-14 and all domains except communication disorder and social disability domain in adolescent and adult patients showed significant changes as well as a decrease trend. Only adults showed significant changes in communication disorder.Both groups had no significant difference. CONCLUSIONS: The impact of comprehensive orthodontic treatment on patients' OHRQoL is quite different. Orthodontists should pay attention to the differences and guide the patients accordingly.

Upper airway asymmetry in skeletal Class III malocclusions with mandibular deviation.

The purpose of this study was to investigate the relationship between bilateral differences of upper airway and mandibular morphologic patterns in subjects with skeletal Class III mandibular deviation. 47 skeletal Class III (ANB < 0°) adult patients with and without mandibular deviation were divided into 2 groups. Bilateral differences of minimum cross-sectional area, mean cross-sectional area, volume of subdivisions (nasopharynx, palatopharynx, glossopharynx, hypopharynx) were assessed paired t test. Stepwise linear regression analysis and Pearson correlation coefficients were computed between a significant pair of upper airway variables and a pair of mandibular deviation variables to examine the quantitative relationship between the upper airway asymmetry and mandibular deviation. The mean cross-sectional area and the volume of palatopharynx on the deviated side in mandibular deviated group was significantly smaller than non-deviated side. The asymmetry index of the palatopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.49) and Ramus asymmetry (r = 0.54). However, in the glossopharyngeal and hypopharyngeal segment, the mandibular deviated group showed significant asymmetry, characterized by larger mean cross-sectional area and volume in deviated side. The asymmetry index of the glossopharyngeal volume and hypopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.42), Me-s (r = 0.72) and Me-s (r = 0.67) respectively.

Assessing changes in quality of life using the Oral Health Impact Profile (OHIP) in patients with different classifications of malocclusion during comprehensive orthodontic treatment.

BACKGROUND: The objectives of this study were to investigated changes in OHRQoL among patients with different classifications of malocclusion during comprehensive orthodontic treatment. METHODS: Clinical data were collected from 81 patients (aged 15 to 24) who had undergone comprehensive orthodontic treatment. Participants were classified 3 groups: Class I (n = 35), II (n = 32) and III (n = 14) by Angle classification. OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14). All subjects were examined and interviewed at baseline (T0), after alignment and leveling (T1), after correction of molar relationship and space closure (T2), after finishing (T3). Friedman 2-way analysis of variance (ANOVA) and Wilcoxon signed rank tests were used to compare the relative changes of OHRQoL among the different time points. A Bonferroni correction with P < 0.005 was used to declare significance. RESULTS: Significant reductions were observed in all seven OHIP-14 domains of three groups except for social disability (P > 0.005) in class I and class II, Handicap in class II and class III (P > 0.005). Class I patients showed significant changes for psychological disability and psychological discomfort domain at T1, functional limitation, physical pain at T2. Class III patients showed a significant benefit in all domains except physical pain and functional limitation. Class II patients showed significant changes in the physical pain, functional disability, and physical disability domains at T1. CONCLUSIONS: The impact of comprehensive orthodontic treatment on patients' OHRQoL do not follow the same pattern among patients with different malocclusion. Class II patients benefits the most from the stage of space closure, while class I patients benefits the first stage (alignment and leveling) of treatment in psychological disability and psychological discomfort domains.

[Correlation analysis between psychosomatic symptoms of adult and cooperation behaviors].

PURPOSE: To investigate whether the psychosomatic symptoms of patients are related to the degree of cooperation. METHODS: Ninety-one malocclusion adults (31 males, 60 females, aged from 20 to 45 years) were selected and determined with Symptom Checklist-90 (SCL-90) to evaluate their psychosomatic symptoms. The inspected and filed noncooperation behaviors were examined and recorded 6 months after orthodontic treatment started. The data was analyzed by one-sample t test, independent-sample t test and Spearman rank correlation coefficient with SPSS 20.0 software package. RESULTS: Adult malocclusion patients scored significantly higher than the nation norm on the factors of interpersonal sensitivity, anxiety, schizophrenia and compulsion (P<0.05). The score of noncooperation behaviors showed a scale of 0 to 19, with an average of 7.2 ± 1.4 points. There was positive correlation between psychological problems and noncooperation behaviors of adult patients (r=0.35). CONCLUSIONS: The study confirms that the psychosomatic symptoms of adult malocclusion patients are associated with the degree of cooperation. Having known well about the psychology of adult malocclusion patient before orthodontic treatment is initiated, and orthodontists can relieve psychological disorders in patients to improve their cooperating quality.

New strategies for prevention and treatment of splenic artery steal syndrome after liver transplantation.

AIM: To explore a prophylactic procedure to prevent splenic artery steal syndrome (SASS), as well as a therapeutic intervention to correct it. METHODS: Forty-three liver transplant patients were enrolled in a non-randomized controlled trial, with the eligible criterion that the diameter of the splenic artery is more than 5 mm and/or 1.5 times of the diameter of the hepatic artery. The procedure of splenic artery banding was performed in 28 of the 43 patients, with the other 15 patients studied as a control group. SASS and other complications were compared between these two groups. A new therapeutic intervention, temporary incomplete blockade of the splenic artery with a balloon, was performed to treat SASS in this study. RESULTS: The incidence of SASS was decreased by banding the splenic artery (0/28 vs 5/15, P = 0.006), and the same result was observed in total complications associated with prophylactic procedures (2/28 vs 6/15, P = 0.014). Five patients in the control group developed SASS within 5 d after OLT, 2 of whom were treated by coil embolization of the splenic artery, whereas the other 3 by temporary blockade of the splenic artery. Reappeared or better hepatic arteries with improved systolic amplitude and increased diastolic flow were detected by Doppler ultrasonography in all the 5 patients. Local splenic ischemic necrosis and nonanastomotic biliary stricture were diagnosed respectively in one patient treated by coil embolization, and no collateral complication was detected in patients treated by temporary blockade of the splenic artery. CONCLUSION: SASS should be avoided during the operation by banding the splenic artery. Temporary blockade of the splenic artery is a new safe and effective intervention for SASS.

[Three-dimensional finite element analysis of different reactive force direction of maxillary protraction on temporomandibular joint].

OBJECTIVE: To analyze the influence of different reactive force direction of protractions on temporomandibular joint (TMJ) by establishing a three-dimensional finite element model (FEM) of craniomaxillofacial complex. METHODS: The CT image of the head of a healthy young male volunteer was obtained.With the help of Mimics software, we established a three-dimensional finite element model of craniomaxillofacial complex which included TMJ. The force pattern of maxillary protraction appliance was imitated. The force (5 N) was applied on the chin and the direction of force was from 22° to 49° relative to the occlusal plane. The displacement and stress distribution of TMJ were analyzed. RESULTS: The contact stress on the maxilla decreased with the angle of the force direction increased from 22° to 40°, and increased with the angle increased from 40° to 49°. The stress on the condyle decreased with the angle of the force direction increased. The stress on the condylar neck decreased initially and then increased with the angle of the force direction increased. Comprehensively, the stress was the smallest when the angle of the force direction was 40°. The clockwise rotation of the mandible was found when the angle of the force direction was smaller than 40°. The displacement value was relatively small when the angle was 40°. CONCLUSIONS: Stress and displacement were relatively small when the angle of the force direction was 40° relative to the occlusal plane.

Uptake of donor lymphocytes treated with 8-methoxypsoralen and ultraviolet A light by recipient dendritic cells induces CD4+CD25+Foxp3+ regulatory T cells and down-regulates cardiac allograft rejection.

Extracorporeal photopheresis (ECP) is an effective immunomodulatory therapy and has been demonstrated to be beneficial for graft-vs-host disease and solid-organ allograft rejection. ECP involves reinfusion of a patient's autologous peripheral blood leukocytes treated ex vivo with 8-methoxypsoralen and UVA light radiation (PUVA). Previous studies focused only on ECP treatment of recipient immune cells. Our study is the first to extend the target of ECP treatment to donor immune cells. The results of in vitro co-culture experiments demonstrate uptake of donor PUVA-treated splenic lymphocytes (PUVA-SPs) by recipient immature dendritic cells (DCs). Phagocytosis of donor PUVA-SPs does not stimulate phenotype maturation of recipient DCs. In the same co-culture system, donor PUVA-SPs enhanced production of interleukin-10 and interferon-gamma by recipient DCs and impaired the subsequent capability of recipient DCs to stimulate recipient naïve T cells. Phagocytosis of donor PUVA-SP (PUVA-SP DCs) by recipient DCs shifted T-cell responses in favor of T helper 2 cells. Infusion of PUVA-SP DCs inhibited cardiac allograft rejection in an antigen-specific manner and induced CD4(+)CD25(high)Foxp3(+) regulatory T cells. In conclusion, PUVA-SP DCs simultaneously deliver the donor antigen and the regulatory signal to the transplant recipient, and thus can be used to develop a novel DC vaccine for negative immune regulation and immune tolerance induction.

[Impact of novel negative immunoregulatory dendritic cells on regulatory T cells in cardiac allograft recipient rats].

AIM: To investigate the effect of recipient dendritic cells (DC) loaded with PUVA-treated donor splenic lymphocytes (PUVA-SP) on CD4(+) CD25(+) regulatory T cells (Treg) and the survival time of cardiac allograft in rats. METHODS: Cardiac allografts from DA donor rats were transplanted into LEW recipient rats. Donor splenic lymphocytes were treated with 8-methoxypsoralen plus UVA irradiation (PUVA). Recipient bone marrow-derived DCs were co-cultured with PUVA-treated donor splenic lymphocytes (PUVA-SP) and the phenotype of the treated DCs was analyzed with flow cytometry. Seven days before transplantation, recipients were given infusion of recipient DCs loaded with PUVA-treated donor splenic lymphocytes (PUVA-SP DC) through the peripheral vein. The cardiac allograft survival time was evaluated by palpation every day. The frequency of CD4(+)CD25(+) T cells and CD4(+) CD25(high) T cells and their Foxp3 expression were analyzed using flow cytometry. Fourteen days after transplantation, T lymphocytes of the recipient rats receiving PUVA-SP DC were transferred to the normal LEW rats. The delayed type hypersensitivity (DTH) of the transferred LEW rats to the donor DA rats antigen then was measured. RESULTS: After co-cultured with PUVA-SP, recipient DCs still maintained an immature phenotype with low levels of MHC II, CD80 and CD86. The injection of PUVA-SP DCs significantly increased the frequencies of CD4(+)CD25(+) T cells and CD4(+) CD25(high) T cells and the expression of Foxp3 in the peripheral blood, and prolonged the allograft survival time. The donor antigen specific hyporesponsiveness could be transferred to normal LEW rats through adoptive transfusion. CONCLUSION: PUVA-SP DCs effectively up-regulate CD4(+) CD25(+) Foxp3(+) Treg and induce donor antigen specific hyporesponsiveness, thus prolonging the allograft survival time.

[Immune regulation effect of rat dendritic cells phagocytosing photochemotherapy-treated allogeneic cells on syngeneic T cells].

The aim of this study was to investigate the immune regulatory effect of dendritic cells phagocytosing photochemotherapy-treated allogeneic spleen lymphocytes on syngeneic T cells. DA rat spleen lymphocytes were treated with 8-methoxypsoralen plus UVA irradiation (PUVA). LEW rat bone marrow-derived DCs were co-cultured with PUVA-treated DA spleen lymphocytes (PUVA-SP), and the surface markers (MHC-II, CD86 and CD40) of treated DC were detected by flow cytometry. CFSE-labeled PUVA SP were incubated with LEW DCs and the phagocytosis of DCs on PUVA-SP was observed by using fluorescent microscope. The ability of DC phagocytosing allogeneic PUVA-SP (PUVA-SP DC) to stimulate the proliferation of LEW T cells was analyzed by mixed leukocyte reactions (MLR). The production of IL-4, IL-10, IL-2, IFN-gamma in MLR culture supernatant was determined by luminex method. The results indicated that the PUVA treatment effectively induced early apoptosis of DA rat spleen lymphocytes. After co-culture, DC efficiently phagocytosed allogeneic PUVA-SP and still maintained an immature phenotype with low levels of MHC II, CD40 and CD86. PUVA-SP DC induced LEW T cell hyporesponsiveness to DA rat antigen, and led to skewing of T cell cytokine expression toward Th2 (IL-10 and IL-4). It is concluded that the PUVA-SP DC effectively down-regulate T cell response to alloantigen and induce Th2 immune deviation in vitro.

The diversity of KIR gene in Chinese Northern Han population and the impact of donor KIR and patient HLA genotypes on outcome following HLA-identical sibling allogeneic hematopoietic stem cell transplantation for hematological malignancy in Chinese people.

Killer cell immunoglobulin-like receptors (KIRs) are members of a group of molecules that specifically recognize HLA class I ligands and are found on subsets of human lymphopoetic cells. The number of KIR loci can vary between individuals, resulting in a heterogeneous array of possible KIR genes. The range of observed profiles has been explained by the occurrence of two haplotype families termed A and B, which can be distinguished on the basis of certain KIR sequences. Immunogenetic analysis of different ethnic populations shows significant differences in terms of the distribution for group A and group B haplotypes. Recently, attention has been focused on the role of killer cell immunoglobulin-like receptor (KIR)-ligand incompatibility in the graft-versus-host direction between donor and recipient in allogeneic hematopoietic stem-cell transplantation (ASCT). The goal of this study was to study the frequency of specific KIR genes in Chinese Northern Han population and evaluate the role of KIR-ligand mismatch in Chinese HLA-identical sibling hematopoietic stem cell transplantation patients with hematological malignancy. Here genomic DNA from 150 Northern Chinese Han individuals was typed for the presence or absence of KIR genes. Seventy-four allogeneic stem cell transplantation donor/recipient pairs were typed for HLA-A, B, C and KIR. Sixteen KIR genes were observed in the population, and framework genes 3DL3, 3DP1, 2DL4, and 3DL2 were present in all individuals. Twenty-two different genotypes were found. Group A haplotypes outnumbered group B haplotypes in frequency by approximately 3:1, with individuals having two group A haplotypes accounting for 51.9% (78/150). We observed that 57 out of 74 (77.3%) donor-recipient pairs could be characterized by lack of recipient HLA ligand for donor KIR. We observed that 36 out of 45 (80%) donor-recipient HLA-identical sibling transplant pairs could be characterized by lack of recipient HLA ligand for donor KIR. Cumulative incidence analysis of aGVHD in patients undergoing HLA-identical sibling hematopoietic stem cell transplantation in this study demonstrated a decreased incidence of severe aGVHD in patients lacking HLA ligand for donor-inhibitory KIR2DL1 (31.4 vs. 70%, P = 0.029). And also in AML (acute myeloid leukemia) patients lacking HLA ligand for donor-inhibitory KIR and KIR2DL1 (17.6 vs. 75%, P = 0.03). Our data demonstrated that the Chinese Han population is distinct in KIR gene frequencies and putative KIR haplotypes in comparison to some other populations. Almost all allogeneic donors could be characterized as having an inhibitory KIR for each of the three known class I ligands. KIR and KIR2DL1 mismatch is associated with lower aGVHD in Chinese after HLA-identical sibling hematopoietic stem cell transplantation.