Mass, Spectroscopy, and Two-Neutron Decay of

The structure and decay of the most neutron-rich beryllium isotope, ^{16}Be, has been investigated following proton knockout from a high-energy ^{17}B beam. Two relatively narrow resonances were observed for the first time, with energies of 0.84(3) and 2.15(5) MeV above the two-neutron decay threshold and widths of 0.32(8) and 0.95(15) MeV, respectively. These were assigned to be the ground (J^{π}=0^{+}) and first excited (2^{+}) state, with E_{x}=1.31(6) MeV. The mass excess of ^{16}Be was thus deduced to be 56.93(13) MeV, some 0.5 MeV more bound than the only previous measurement. Both states were observed to decay by direct two-neutron emission. Calculations incorporating the evolution of the wave function during the decay as a genuine three-body process reproduced the principal characteristics of the neutron-neutron energy spectra for both levels, indicating that the ground state exhibits a strong spatially compact dineutron component, while the 2^{+} level presents a far more diffuse neutron-neutron distribution.

Radiologic-histopathologic correlation of fatty island sign with fat necrosis in atypical lipomatous tumor and lipoma.

AIM: This study aimed to assess the imaging features of atypical lipomatous tumors (ALTs) and lipoma with fat necrosis. METHODS: This study included patients with histopathologically proven fat necrosis within adipocytic tumors who underwent preoperative imaging. Magnetic resonance imaging (MRI) and/or computer tomography (CT) findings of fat necrosis associated with lipomatous tumors were retrospectively reviewed, emphasizing the "fatty island sign (FIS)." FISs were defined as well-demarcated, focal fat-containing areas surrounded by more thickened septa compared with other intratumoral septa. Imaging findings of FIS were compared between ALT and lipoma. RESULTS: Fat necrosis was histopathologically confirmed in 17 patients (6 ALTs and 11 lipomas). Among them, 18 FISs were observed in 10 lesions (59%). Multiple FISs within a lesion were observed in 4 (40%) patients. The median maximum diameter of the FISs was 37 mm. Hypointense areas within FISs relative to the subcutaneous fat on T1- and T2-weighted images were observed in 8 (80%) and 9 (90%), respectively, whereas hyperintense areas within FISs on fat-suppressed T2-weighted images were observed in 2 (20%). Nonfatty solid components within FISs were observed in 2 (20%). On CT, increased fat attenuation and pure fat attenuation within FISs were observed in 6 (86%) and 1 (14%), respectively. The imaging findings of FIS were not significantly different between ALT and lipoma. CONCLUSION: FISs were observed in 59% of the histologically proven ALT and lipoma patients with fat necrosis. The hypointense areas relative to the subcutaneous fat on T1- and T2-weighted images and increased fat attenuation on CT were usually observed within FISs.

Anti-A and anti-B titers, age, gender, biochemical parameters, and body mass index in Japanese blood donors.

It has been reported that anti-A and anti-B (ABO antibody) titers decrease with age, but little is known about the association between ABO antibody titers and physiologic/biochemical parameters such as body mass index (BMI), gamma-glutamyl transpeptidase (GGT), and total cholesterol (T-Cho). We investigated the present situation of ABO antibody titers among healthy blood donors in Japan and the physiologic/biochemical factors that may be associated with changes in ABO antibody titers. Plasma from 7450 Japanese blood donors was tested for ABO antibody titers using ABO reverse typing reagents by an automated microplate system; donor samples were classified into low, middle, and high titers according to the agglutination results obtained with diluted plasma samples. Multivariate regression analysis was performed to analyze the association between ABO antibody titers and age, gender, biochemical parameters (alanine transaminase [ALT], GGT, globulin, T-Cho, and glycosylated albumin [GA]), and BMI according to the ABO blood groups. A significant correlation between ABO antibody titers and age/gender, except for gender in anti-A of blood group B donors, was observed. BMI showed significant but negative correlations with anti-A and anti-B (ß = -0.085 and -0.062, respectively; p < 0.01) in blood group O donors. In addition, significant but negative correlations between GGT and T-Cho with anti-B of blood group A donors (ß = -0.055 and -0.047, respectively; p < 0.05) were observed. Although differences existed among the ABO blood groups, ABO antibody titers seem to be associated with physiologic and biochemical parameters of healthy individuals.

Biochemical characterization of Bombyx mori α-N-acetylgalactosaminidase belonging to the glycoside hydrolase family 31.

Horizontal gene transfer is an important evolutionary mechanism not only for bacteria but also for eukaryotes. In the domestic silkworm Bombyx mori, a model species of lepidopteran insects, some enzymes are known to have been acquired by horizontal transfer; however, the enzymatic features of protein BmNag31, belonging to glycoside hydrolase family 31 (GH31) and whose gene was predicted to be transferred from Enterococcus sp. are unknown. In this study, we reveal that the transcription of BmNag31 increases significantly during the prepupal to pupal stage, and decreases in the adult stage. The full-length BmNag31 and its truncated mutants were heterologously expressed in Escherichia coli and characterized. Its catalytic domain exhibits α-N-acetylgalactosaminidase activity and the carbohydrate-binding module family 32 domain shows binding activity towards N-acetylgalactosamine, similar to the Enterococcus faecalis homolog, EfNag31A. Gel filtration chromatography and blue native polyacrylamide gel electrophoresis analyses indicate that BmNag31 forms a hexamer whereas EfNag31A is monomeric. These results provide insights into the function of lepidopteran GH31 α-N-acetylgalactosaminidase.

Quasifree Neutron Knockout Reaction Reveals a Small s-Orbital Component in the Borromean Nucleus

A kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus ^{17}B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s_{1/2} and 0d_{5/2} orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s_{1/2}. Our finding of such a small 1s_{1/2} component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in ^{17}B. The present work gives the smallest s- or p-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo.

Surface Localization of the Dineutron in

The formation of a dineutron in the ^{11}Li nucleus is found to be localized to the surface region. The experiment measured the intrinsic momentum of the struck neutron in ^{11}Li via the (p,pn) knockout reaction at 246 MeV/nucleon. The correlation angle between the two neutrons is, for the first time, measured as a function of the intrinsic neutron momentum. A comparison with reaction calculations reveals the localization of the dineutron at r∼3.6 fm. The results also support the density dependence of dineutron formation as deduced from Hartree-Fock-Bogoliubov calculations for nuclear matter.

Pancreatic MRI associated with pancreatic fibrosis and postoperative fistula: comparison between pancreatic cancer and non-pancreatic cancer tissue.

AIM: To evaluate the potential value of magnetic resonance imaging (MRI) for predicting postoperative pancreatic fistula (POPF) in patients with pancreatic cancer (PC) and non-pancreatic cancer (non-PC). MATERIAL AND METHODS: This retrospective study was approved by the institutional review board and written informed consent was waived. Forty patients underwent pancreatoduodenectomy due to PC (n=31) and non-PC (n=9). The pancreas-to-muscle signal intensity ratio (SIR) on three-dimensional (3D)- fast field echo (FFE) T1-, in- and opposed-phase T1-, and T2-weighted images, as well as the apparent diffusion coefficient (ADC) value of the pancreas were measured. The frequency of POPF and MRI measurements were compared between patients with PC and non-PC. The MRI measurements were also compared with the grade of pancreatic fibrosis on pathological findings, fat deposition, and interstitial oedema. RESULTS: The frequency of POPF was significantly higher in patients with non-PC than in those with PC (p=0.0067), with an odds ratio of 10.4. The SIR on 3D-FFE T1-weighted images was significantly higher in patients with non-PC (p=0.0001) and those with POPF (p=0.017) than in those with PC and those without POPF, respectively. Multiple regression analysis demonstrated that the SIR on 3D-FFE T1-weighted image was independently associated with the grade of pancreatic fibrosis (p<0.0001). CONCLUSION: The frequency of POPF was significantly higher in patients with non-PC than in those with PC was inversely related to the grade of pancreatic fibrosis. The SIR on 3D-FFE T1-weighted image might be a potential imaging biomarker for predicting POPF.

CT and MRI characteristics for differentiating mediastinal Müllerian cysts from bronchogenic cysts.

AIM: To evaluate how computed tomography (CT) and magnetic resonance imaging (MRI) characteristics can be used to differentiate immunohistochemically confirmed mediastinal Müllerian cysts (MMCs) from bronchogenic cysts (BCs). MATERIALS AND METHODS: Sixteen patients with histopathologically and immunohistochemically confirmed mediastinal cysts (four with MMCs and 12 with BCs) were included in this study. CT and MRI images were reviewed retrospectively and the location, size, CT attenuation, and MRI signal intensity of the two pathologies were compared. RESULTS: On review of CT images, cysts could be located to the anterior mediastinum in four BCs, middle mediastinum in three MMCs and seven BCs, and posterior mediastinum in one MMC and one BC. Contact with a vertebral body was observed in 4/4 MMCs (100%) and 6/12 BCs (50%). The ratios of minimum-to-maximum diameter (0.57±0.09 versus 0.74±0.11, p<0.01), CT attenuation (7.8±6 versus 44.3±12 HU, p<0.01), and cyst-to-spinal cord signal intensity ratios (SIRs) on T1-weighted images (0.56±0.2 versus 1.31±0.4, p<0.01) were significantly lower for MMCs than BCs. No significant differences in maximum diameter, minimum diameter, and SIRs on T2-weighted images were found between MMCs and BCs. CONCLUSION: In characterising mediastinal cysts in a middle-aged female patient, contact with a vertebral body, flattened configuration, hypodensity on CT, and hypointensity compared to spinal cord on T1-weighted images are features that are specific to MMCs.

Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the Sun.

We analyze the Sun's shadow observed with the Tibet-III air shower array and find that the shadow's center deviates northward (southward) from the optical solar disk center in the "away" ("toward") interplanetary magnetic field (IMF) sector. By comparing with numerical simulations based on the solar magnetic field model, we find that the average IMF strength in the away (toward) sector is 1.54±0.21_{stat}±0.20_{syst} (1.62±0.15_{stat}±0.22_{syst}) times larger than the model prediction. These demonstrate that the observed Sun's shadow is a useful tool for the quantitative evaluation of the average solar magnetic field.

The B allele with a 5·8 kb deletion in intron 1 of the ABO gene is the major allele in Japanese individuals with Bm and A1 Bm phenotypes.

Bm and A1 Bm phenotypes are the most frequent ABO variants in the Japanese population. The B antigen on Bm red blood cells is only detectable by adsorption and elution tests, and plasma B-transferase activity is usually detected at half or less levels compared with that of common B. Recently, a B allele lacking an erythroid cell-specific transcription enhancer in intron 1 of the ABO gene was identified from individuals with Bm and A1 Bm phenotypes, which could explain the unique serologic properties of Bm . In the Japanese Red Cross Society, eight Blood Centers tested blood samples from donors throughout Japan and collected blood samples from 888 Bm and 415 A1 Bm individuals. DNA analysis revealed that 1300 of 1303 (99·77%) individuals had the B allele with a 5·8 kb deletion (c.28 + 5110_10889del), which included the enhancer element.

Crystalline structure of pulverized dental calculus induces cell death in oral epithelial cells.

BACKGROUND AND OBJECTIVE: Dental calculus is a mineralized deposit attached to the tooth surface. We have shown that cellular uptake of dental calculus triggers nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation, leading to the processing of the interleukin-1ß precursor into its mature form in mouse and human phagocytes. The activation of the NLRP3 inflammasome also induced a lytic form of programmed cell death, pyroptosis, in these cells. However, the effects of dental calculus on other cell types in periodontal tissue have not been investigated. The aim of this study was to determine whether dental calculus can induce cell death in oral epithelial cells. MATERIAL AND METHODS: HSC-2 human oral squamous carcinoma cells, HOMK107 human primary oral epithelial cells and immortalized mouse macrophages were exposed to dental calculus or 1 of its components, hydroxyapatite crystals. For inhibition assays, the cells were exposed to dental calculus in the presence or absence of cytochalasin D (endocytosis inhibitor), z-YVAD-fmk (caspase-1 inhibitor) or glyburide (NLRP3 inflammasome inhibitor). Cytotoxicity was determined by measuring lactate dehydrogenase (LDH) release and staining with propidium iodide. Tumor necrosis factor-α production was quantified by enzyme-linked immunosorbent assay. Oral epithelial barrier function was examined by permeability assay. RESULTS: Dental calculus induced cell death in HSC-2 cells, as judged by LDH release and propidium iodide staining. Dental calculus also induced LDH release from HOMK107 cells. Following heat treatment, dental calculus lost its capacity to induce tumor necrosis factor-α in mouse macrophages, but could induce LDH release in HSC-2 cells, indicating a major role of inorganic components in cell death. Hydroxyapatite crystals also induced cell death in both HSC-2 and HOMK107 cells, as judged by LDH release, indicating the capacity of crystal particles to induce cell death. Cell death induced by dental calculus was significantly inhibited by cytochalasin D, z-YVAD-fmk and glyburide, indicating NLRP3 inflammasome involvement. In permeability assays, dental calculus attenuated the barrier function of HSC-2 cell monolayers. CONCLUSION: Dental calculus induces pyroptotic cell death in human oral epithelial cells and the crystalline structure plays a major role in this process. Oral epithelial cell death induced by dental calculus might be important for the etiology of periodontitis.

Health state utility values and patient-reported outcomes before and after vertebral and non-vertebral fractures in an osteoporosis clinical trial.

We assessed the health state utility value (HSUV) reductions associated with vertebral fractures using data collected in the Japanese Osteoporosis Intervention Trial-03 (JOINT-03). Our analysis revealed that assessment of HSUVs after morphometric vertebral fracture is important to capture the burden of vertebral fractures. INTRODUCTION: Evaluation of the HSUV after fracture is important to calculate the quality-adjusted life years (QALYs) of osteoporosis patients, which is essential information in the context of health economic evaluation. METHODS: JOINT-03 study patients were aged ≥65 years and treated with risedronate and vitamin K2 or risedronate alone. Radiographic information and patient-reported outcomes measured by EQ-5D and a visual analogue scale (VAS) were assessed at registration and followed up after 6, 12, and 24 months. According to differences among the dates of these assessments and the radiographic information, we classified the follow-up HSUVs calculated based on EQ-5D results into before or after fracture categories regardless of clinical symptoms. RESULTS: Among 2922 follow-up HSUVs, 201 HSUVs were categorized as HSUVs that were observed after incident vertebral fractures on X-ray films. The median time from the detection of an incident vertebral fracture until the EQ-5D assessment was 53 days (25th percentile, 0 day; 75th percentile, 357 days). The impact of incident vertebral fractures on HSUVs was quantified as -0.03. Among the five health profile domains on the EQ-5D, an incident vertebral fracture had significant effects on anxiety/depression, self-care, and usual activities. CONCLUSIONS: The results suggest that incident morphometric vertebral fracture was associated with impairment of the HSUV for patients with osteoporosis not only immediately but also several months after the fracture.

Short communication: Neonatal calves coagulate first-milking colostrum and produce a large curd for efficient absorption of immunoglobulins after first ingestion.

Calves are fed milk and milk replacer for their growth until approximately 2 mo after birth. During this period, their abomasa produce curd and whey from milk. It has been thought that curd formation is important for digestion and absorption of milk nutrients and immune substances in calves. However, no study has been done observing abomasal contents in neonatal calves after first ingestion of first milking colostrum. Here we report curd formation in neonatal calves and its physiological function with a focus on immunoglobulin absorption. We first examined curd formation by ultrasonography in 3 neonatal calves after first ingestion of first-milking colostrum. Between 0.5 and 8 h after colostrum ingestion, a curd was visualized as a large echogenic image with a clear outline, which was surrounded by an anechoic image corresponding to whey. We next compared serum IgG and IgA concentrations in 10 calves fed the pooled colostrum and 7 calves fed the whey solution that did not coagulate into curds. Serum from 1 calf in the pooled colostrum sample set was excluded due to incomplete curd formation in that the whole colostrum did not coagulate into a large mass of curd and a portion of the colostrum remained as its residue caseins detectable from the abomasal fluid. Serum IgG and IgA concentrations were significantly higher in the 9 calves fed the colostrum than the 7 calves fed the whey solution. One calf exhibiting incomplete curd formation showed low levels of serum IgG and IgA after ingestion, similar to the calves fed the whey solution. These results indicate that curd formation is associated with IgG and IgA absorption in neonatal calves after first ingestion of colostrum.

Two-dimensional gas chromatography time-of-flight mass spectrometry-based serum metabolic fingerprints of neonatal calves before and after first colostrum ingestion.

Neonatal calves show a remarkable increase in serum IgG levels after first ingestion of colostrum. They can absorb high-molecular IgG from colostrum in the small intestine by nonspecific receptor-independent fluid pinocytosis within 24 h after birth. However, little is known about the temporal changes in serum small-molecule metabolites, such as carbohydrates and AA, in neonatal calves after first colostrum ingestion. In this study, we examined temporal changes in serum metabolites of neonatal calves after first ingestion of colostrum by comprehensive 2-dimensional gas chromatography mass spectrometry (GC×GC-MS). Forty serum samples obtained from 5 calves at 8 time points between 0 and 12 h after first colostrum ingestion were analyzed in triplicate by GC×GC-MS. Multivariate analyses of 120 GC×GC-MS results revealed significant variations in the serum metabolites, primary individual differences among the calves, and secondary temporal changes within each individual calf. Several serum metabolites increased temporally after ingestion in each calf, but only a limited number of compounds were increased universally in all 5 calves. Eight compounds, including oligosaccharides such as lactose, were associated with temporal changes in IgG. Some essential AA that must be supplied from the diet increased temporally after ingestion, but differed from the temporal pattern of the oligosaccharides and IgG. These results suggest that the colostral contents may be absorbed by complex mechanisms that include intestinal pinocytosis for IgG and oligosaccharides, along with others such as specific transporters in the intestinal epithelial cells for AA in calves.

Sequence and localization of an ultraviolet (sws1) opsin in the retina of the Japanese sardine Sardinops melanostictus (Teleostei: Clupeiformes).

A full-length complementary (c)DNA encoding ultraviolet (UV)-sensitive opsin (sws1) was isolated from the retina of the Japanese sardine Sardinops melanostictus. The sws1 phylogenetic tree showed a sister group relationship with the Cypriniformes, following the ray-finned fish phylogeny. By expressing reconstituted opsin in vitro, it was determined that the maximum absorbance spectrum (λmax ) of sws1 is around 382 nm, being intermediate in position between two subtypes of sws1 pigment that are UV sensitive (λmax = 355-380 nm) and violet sensitive (λmax = 388-455 nm), which have been reported to date. The ocular media transmitted >20% transmittance of light in the range of 360-600 nm. In situ hybridization analyses revealed that sws1 messenger (m)RNA is localized in a central single cone surrounded by four double cones in a square mosaic. The square mosaic occupies the ventro-temporal quadrant of the retina and the in situ hybridization signals were dominant in this area suggesting that the fish may use UV vision when looking upward. Based on these results, considerable significances of potential UV sensitivity, in relation to characteristic habits of S. melanostictus, are discussed.

Intestinal epithelial culture under an air-liquid interface: a tool for studying human and mouse esophagi.

This study investigated whether an intestinal epithelial culture method can be applied to mouse and human esophageal cultures. The esophagi harvested from 1-day-old mice and adult humans were maintained in collagen gels. A commercially available culture medium for human embryonic stem cells was used for the human esophageal culture. We discovered that the intestinal epithelial culture method can be successfully applied to both mouse and human esophageal cultures. The long-term cultured esophageal organoids were rod-like luminal structures lined with myofibroblasts. We discovered that regeneration of the esophageal mucosal surface can be almost completely achieved in vitro, and the advantage of this method is that organoid cultures may be generated using host-derived fibroblasts as a niche. This method is a promising tool for mouse and human research in intestinal biology, carcinogenesis, and regenerative medicine.

Extension of the N=40 Island of Inversion towards N=50: Spectroscopy of (66)Cr, (70,72)Fe.

We report on the measurement of the first 2(+) and 4(+) states of (66)Cr and (70,72)Fe via in-beam γ-ray spectroscopy. The nuclei of interest were produced by (p,2p) reactions at incident energies of 260 MeV/nucleon. The experiment was performed at the Radioactive Isotope Beam Factory, RIKEN, using the DALI 2γ-ray detector array and the novel MINOS device, a thick liquid hydrogen target combined with a vertex tracker. A low-energy plateau of 2(1)(+) and 4(1)(+) energies as a function of the neutron number was observed for N≥38 and N≥40 for even-even Cr and Fe isotopes, respectively. State-of-the-art shell model calculations with a modified Lenzi-Nowacki-Poves-Sieja (LNPS) interaction in the pfg(9/2)d(5/2) valence space reproduce the observations. Interpretation within the shell model shows an extension of the island of inversion at N=40 for more neutron-rich isotopes towards N=50.

Enhanced in vitro biological activity generated by surface characteristics of anodically oxidized titanium--the contribution of the oxidation effect.

Anodically oxidized titanium surfaces, prepared by spark discharge, have micro-submicron surface topography and nano-scale surface chemistry, such as hydrophilic functional groups or hydroxyl radicals in parallel. The complexity of the surface characteristics makes it difficult to draw a clear conclusion as to which surface characteristic, of anodically oxidized titanium, is critical in each biological event. This study examined the in vitro biological changes, induced by various surface characteristics of anodically oxidized titanium with, or without, release of hydroxyl radicals onto the surface. Anodically oxidized titanium enhanced the expression of genes associated with differentiating osteoblasts and increased the degree of matrix mineralization by these cells in vitro. The phenotypes of cells on the anodically oxidized titanium were the same with, or without, release of hydroxyl radicals. However, the nanomechanical properties of this in vitro mineralized tissue were significantly enhanced on surfaces, with release of hydroxyl radicals by oxidation effects. In addition, the mineralized tissue, produced in the presence of bone morphogenetic protein-2 on bare titanium, had significantly weaker nanomechanical properties, despite there being higher osteogenic gene expression levels. We show that enhanced osteogenic cell differentiation on modified titanium is not a sufficient indicator of enhanced in vitro mineralization. This is based on the inferior mechanical properties of mineralized tissues, without either being cultured on a titanium surface with release of hydroxyl radicals, or being supplemented with lysyl oxidase family members.

Biological significance of fluorine-18-α-methyltyrosine (FAMT) uptake on PET in patients with oesophageal cancer.

PURPOSE: (18)F-FAMT as an amino-acid tracer for positron emission tomography (PET) is useful for detecting human neoplasms. (18)F-FAMT is accumulated in tumour cells solely via L-type amino-acid transporter 1 (LAT1). This study was conducted to investigate the biological significance of (18)F-FAMT uptake in patients with oesophageal cancer. METHODS: From April 2008 to December 2011, 42 patients with oesophageal cancer underwent both (18)F-FAMT PET/CT and (18)F-FDG PET/CT before surgical treatment. The immunohistochemical analysis of LAT1, CD98, Ki-67, CD34, p53, p-Akt and p-mTOR was performed on the primary lesions. In vitro experiments were performed to examine the mechanism of (18)F-FAMT uptake. RESULTS: High uptake of (18)F-FAMT was significantly associated with advanced stage, lymph node metastasis and the expression of LAT1, CD98, Ki-67 and CD34. LAT1 expression yielded a statistically significant correlation with CD98 expression, cell proliferation, angiogenesis and glucose metabolism. In vitro experiments revealed that (18)F-FAMT was specifically transported by LAT1. CONCLUSIONS: The uptake of (18)F-FAMT within tumour cells is determined by the LAT1 expression and correlated with cell proliferation and angiogenesis in oesophageal cancer. The present experiments also confirmed the presence of LAT1 as an underlying mechanism of (18)F-FAMT accumulation.

Suppression of allo-human leucocyte antigen (HLA) antibodies secreted by B memory cells in vitro: intravenous immunoglobulin (IVIg)†versus a monoclonal anti-HLA-E IgG that mimics HLA-I reactivities of IVIg.

B memory cells remain in circulation and secrete alloantibodies without antigen exposure > 20 years after alloimmunization postpartum or by transplantation. These long-lived B cells are resistant to cytostatic drugs. Therapeutically, intravenous immunoglobulin (IVIg) is administered to reduce allo-human leucocyte antigen (HLA) antibodies pre- and post-transplantation, but the mechanism of reduction remains unclear. Recently, we reported that IVIg reacts with several HLA-I alleles and the HLA reactivity of IVIg is lost after its HLA-E reactivity is adsorbed out. Therefore, we have generated an anti-HLA-E monoclonal antibody that mimics the HLA-reactivity of IVIg to investigate whether this antibody suppresses IgG secretion, as does IVIg. B cells were purified from the blood of a woman in whose blood the B memory cells remained without antigen exposure > 20 years after postpartum alloimmunization. The B cells were stimulated with cytokines using a well-defined culture system. The anti-HLA-E monoclonal antibody (mAb) significantly suppressed the allo-HLA class-II IgG produced by the B cells, and that this suppression was far superior to that by IVIg. These findings were confirmed with HLA-I antibody secreted by the immortalized B cell line, developed from the blood of another alloimmunized woman. The binding affinity of the anti-HLA-E mAb for peptide sequences shared (i.e. shared epitopes) between HLA-E and other ß2-microglobulin-free HLA heavy chains (open conformers) on the cell surface of B cells may act as a ligand and signal suppression of IgG production of activated B memory cells. We propose that anti-HLA-E monoclonal antibody may also be useful to suppress allo-HLA IgG production in vivo.