•This CLEIA for detecting SEA was developed by using a pair of highly specific mAbs.•This CLEIA for the detecting SEA is highly sensitive and specific.•It can be successfully applied to the analysis of SEA in a variety of environmental, biological matrices.In this study, detection of staphylococcal enterotoxin A (SEA) in multi-matrices using a highly sensitive and specific microplate chemiluminescence enzyme immunoassay (CLEIA) has been established. A pair of monoclonal antibodies (mAbs) was selected from 37 anti-SEA mAbs by pairwise analysis, and the experimental conditions of the CLEIA were optimized. This CLEIA exhibited high performance with a wide dynamic range from 6.4 pg mL−1 to 1600 pg mL−1, and the measured low limit of detection (LOD) was 3.2 pg mL−1. No cross-reactivity was observed when this method was applied to test SEB, SEC1, and SED. It has also been successfully applied for analyzing SEA in a variety of environmental, biological, and clinical matrices, such as sewage, tap water, river water, roast beef, peanut butter, cured ham, 10% nonfat dry milk, milk, orange juice, human urine, and serum. Thus, the highly sensitive and SEA-specific CLEIA should make it attractive for quantifying SEA in public health and diagnosis in near future.

The discovery of Sema 4D can be dated to 1992, when Boumsell's team reported a novel 150-kDa glycoprotein dimer. It was expressed on T lymphocytes that had been activated with CD3 monoclonal antibody or phytohaemagglutinin.1 Hence, this molecule has been designated CD100 by the International Workshop on Human Leukocyte Differentiation Antigen. In 1996, 3 years after the discovery of the semaphorin family,2 the CD100 gene was cloned and identified as the first semaphorin with immune system functions.3 Unlike the prototypical semaphorins, which are neuronal chemorepellents, Sema 4D/CD100 together with Sema 3A, Sema 4A, Sema 6D and Sema 7A have been described as ‘immune semaphorins’, because they are expressed on T cells, B cells, natural killer cells and dendritic cells, and exhibit a variety of immunological functions.4The Sema 4D/CD100 molecule can bind to several receptors. CD72, a member of the C-type lectin family, is a low-affinity Sema 4D/CD100 receptor that is expressed on immune cells, such as B cells, dendritic cells, macrophages and mast cells (Figure 1a).5 At least three Sema 4D/CD100 receptors are plexin family members. The high-affinity Sema 4D/CD100 receptor plexin B1 is mainly expressed on endothelial cells and epithelial cells (Figure 1b),6 whereas plexin B2 and plexin C1 are low-affinity receptors for Sema 4D/CD100.7Recently, Witherden et al.8 demonstrated that the interaction of Sema 4D/CD100 with plexin B2 plays a key role in activating skin-resident γδ T cells (DETCs) in mice to respond to tissue damage (Figure 1c). The morphological changes in DETCs that precede cutaneous wound healing appear to be associated with the activation of key actin regulators in response to Sema 4D/CD100's binding with its ligand. This is the first example indicating that Sema 4D/CD100 is not only a ligand for plexin B1 or CD72 but also a direct signaling receptor in mediating Sema 4D/CD100-plexin B's biological functions. It is not surprising to identify Sema 4D/CD100-plexin B as a counter-receptor, because many counter-receptors have already been well documented in the B7-CD28 family and TNF–TNFR superfamilies.Another important point in Witherden's paper8 is that the Sema 4D/CD100 molecule on γδ T cells mediates a function involved in innate immunity. Bonneville9 pointed out that plexin B2 is broadly expressed on many epithelial tissues where resident CD100-expressing γδ T cells are located, suggesting that the Sema 4D/CD100–plexin B2 interaction may play a more general role in the immune control of the integrity of epithelial barriers.It is thought that, similar to αβ T cells, complete activation of DETCs requires costimulatory signals. DETCs do not express many of the usual coreceptors that are important for αβ T-cell activation, such as CD4 or CD8, or the costimulatory molecule CD28. In 2010, Witherden et al.10 identified a receptor–ligand pair, junctional adhesion molecule-like molecule and the cocksackie adenovirus receptor (CAR), which plays a crucial role in the DETC response. In addition, DETCs can recognize a stress- or damage-induced keratinocyte self-antigen through their γδ T-cell receptor (TCR), without the requirement for antigen presentation by MHC class I or class II molecules. More recently, Komori et al.11 demonstrated the presence of an as yet-uncharacterized antigen that is expressed on the surface of damaged keratinocytes and is recognized by the canonical TCR expressed by DETCs. Furthermore, Witherden et al.8 proposed that when keratinocytes are damaged, they express a self-antigen, plexin B2 and CAR, which can be recognized by the γδ TCR, Sema 4D/CD100 and junctional adhesion molecule-like molecule, respectively, on neighboring γδ T cells (Figure 1c). Therefore, these interactions may play a key role in regulating the ERK and cofilin signaling pathways of activated γδ T cells, leading to morphologic changes and the release of keratinocyte growth factor type 1 (KGF1) and KGF2. These growth factors can induce the proliferation and migration of keratinocytes and the restoration of epithelial integrity.This study was supported by The National Natural Science Foundation of China (No. 30930087).

Botulinum neurotoxins (BoNTs) are the most poisonous substances ever known. The early detection of these toxins could bear more time for appropriate medical intervention. The standard method for detecting BoNTs is the mouse bioassay, which is time consuming (up to 4 days) and requires a large number of laboratory animals. The immunologic detection methods could detect the toxins within a day, but most of these methods are less sensitive compared with the mouse bioassay due to the lack of high-affinity antibodies. Recently, the recombinant HC subunit of botulinum neurotoxin type A (rAHC) was expressed as an effective vaccine against botulism, indicating that the rAHC could be an effective immunogen that raises the monoclonal antibody (mAb) for detecting BoNT/A. After immunized BALB/c mice with rAHC, 56 mAbs were generated. Two of these mAbs were selected to establish a highly sensitive sandwich chemiluminescence enzyme immunoassay (CLEIA), in which FMMU-BTA-49 and FMMU-BTA-22 were used as capture antibody and detection antibody, respectively. The calculated limit of detection (LOD) based on molecular weight of rAHC and BoNT/A reached 0.45 pg mL−1. This CLEIA can be used in the detection of BoNT/A in matrices such as milk and beef extract. This method has 20–40 fold lower LOD than that of the mouse bioassay and takes only 3 h to complete the detection, indicating that it can be used as a valuable method to detect and quantify BoNT/A.Graphical abstractHighlights► The rAHC could elict highly protective antibody titer as vaccine. ► Two anti-rAHC mAbs were selected to form the sensitive CLEIA for detecting BoNT/A. ► The CLEIA detecting BoNT/A is more sensitive than that of the ELISA reported.

Calreticulin (CRT) is an endoplasmic reticulum luminal Ca2+-binding chaperone protein. By immunizing mice with recombinant fragment (rCRT/39-272), six clones of monoclonal antibodies (mAbs) were generated and characterized. Based on these mAbs, a microplate chemiluminescent enzyme immunoassay (CLEIA) system with a measured limit of detection of 0.09 ng/ml was developed. Using this CLEIA system, it was found that soluble CRT (sCRT) level in serum samples from 58 lung cancer patients was significantly higher than that from 40 healthy individuals (only 9 were detectable, P < 0.0001). Among them, serum sCRT in the small cell lung cancer was lower than that in adenocarcinoma (P = 0.0085), while both were lower than that in the squamous cell carcinoma (P = 0.013, P = 0.0012, respectively). Moreover, it was found that sCRT in sera from the patients after chemotherapy was higher than that from the patients without chemotherapy (P = 0.042). Further study by immunohistochemistry showed that CRT was also highly expressed in the cytoplasm and on the membrane of the lung cancer cells, while there was a trace amount of CRT expression in normal lung cells. Correspondingly, the expression level of CRT on lung cancer cell membrane was associated with the tumor pathological grade. This study demonstrates that sCRT concentration in sera of lung cancer patients is higher than that in sera of healthy individuals, and CRT expression level on lung cancer cell membrane is associated with tumor pathological classification and grade. These findings suggest that CRT may be used as a biomarker in lung cancer prediction and diagnosis.

A highly specific and sensitive microplate chemiluminescent enzyme immunoassay (CLEIA) was established and validated for the detection of staphylococcal enterotoxin B (SEB). A pair of monoclonal antibodies (mAbs) that recognizes different epitopes of SEB was selected from 20 SEB-specific mAbs, and the experimental conditions were examined and optimized for the development of the CLEIA. This method exhibited high performance with a dynamic range of 0.01−5 ng/mL, and the measured limit of detection (LOD) was 0.01 ng/mL. Intra- and interassay coefficient variations were all lower than 13% at three concentrations (0.2, 0.4, and 2 ng/mL). For specificity studies, when this method was applied to test staphylococcal enterotoxins A, C1, and D, no cross-reactivity was observed. It has been successfully applied to the analysis of SEB in a variety of environmental, biological and humoral matrices such as sewage, tap water, river water, roast beef, peanut butter, cured ham, 10% nonfat dry milk, milk, orange juice, and human urine and serum. The aim of this article is to show that the highly sensitive, specific, and simple microplate CLEIA, based on a pair of highly specific monoclonal antibodies, has potential applications for quantifying SEB in public health and military reconnaissance.

Immunoglobulin superfamily (IgSF) members account for a large proportion of cell adhesion molecules that perform important immunological functions, including recognizing a variety of counterpart molecules on the cell surface or extracellular matrix. The findings that CD155/poliovirus receptor (PVR) and CD112/nectin-2 are the ligands for CD226/platelet and T-cell activation antigen 1 (PTA1)/DNAX accessory molecular-1 (DNAM-1), CD96/tactile and Washington University cell adhesion molecule (WUCAM) and that CD226 is physically and functionally associated with lymphocyte function-associated antigen-1 (LFA-1) on natural killer (NK) and activated T cells have largely expanded our knowledge about the functions of CD226, CD96, WUCAM and LFA-1 and their respective ligands, CD155, CD112, intercellular adhesion molecule (ICAM)-1 and junctional adhesion molecule (JAM)-1. The interactions of these receptors and their ligands are involved in many key functions of immune cells including naive T cells, cytotoxic T cells, NK cells, NK T cells, monocytes, dendritic cells, mast cells and platelets/megakaryocytes.

Granulocyte colony-stimulating factor (G-CSF) is a common inducer of the release of hematopoietic progenitor cells (HPC) from the bone marrow into the peripheral blood. However, the molecular mechanisms underlying this action of G-CSF have not been fully elucidated. Herein, we demonstrate that G-CSF is a powerful chemotactic agent for human HPC other than modulating the adhesion molecules expressed on HPC or bone marrow stromal cells. G-CSF directly chemoattracted HPC in transwell assay and this chemotaxis is time dependent and is specifically neutralized with antibodies that target its receptor. The number of cells transmigrated through the transwell toward G-CSF stimuli was more than that of stromal cell-derived factor-1 at every concentration. G-CSF induced a rapid, transient increase in F-actin polymerization and the formation of focal contact rings in HPC, which are prerequisites for cell migration. The mechanism of G-CSF-induced chemotaxis appears to involve the phosphorylation of JAK1/STAT3 pathway. Collectively, these results provide evidence that G-CSF promotes chemotactic functionality and suggests new avenues of investigation relevant to the mobilization of HPC.

A highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) kit was established for quantifying ovomucoid from hen’s egg white, which has been considered as one of the major allergen in egg white. The detection limit reached 0.041 ng/mL, and linearity ranged from 0.1 to 6.25 ng/mL. Intra- and interassay coefficient variations were all lower than 5% at three concentrations (0.5, 2.5, and 5 ng/mL). No cross-reactivity was observed with bovine serum, horse serum, goat serum, human serum, duck egg white, goose egg white, quail egg white, and pigeon egg white, but a low level of cross-reactivity was found with chicken serum. The ELISA kit was established on the basis of two monoclonal antibodies (mAbs) recognizing different epitopes of ovomucoid. However, these mAbs were generated using commercially purified ovalbumin as immunogen. Studies on the relative allergenicity and antigenicity of egg white protein have been performed by many researchers, but there were controversial opinions reported previously because of the impurity of each egg white protein used in various studies. In the present work we measured the degree of ovomucoid contamination in commercially purified ovalbumin sample, and the value was about 11%. We also determined the ovomucoid residue in influenza vaccine samples for the first time. These data showed that the ELISA kit we established could serve as an effective method for precisely quantifying concentrations of ovomucoid in the egg industry and as a useful tool for the research of allergenicity and antigenicity of hen’s egg proteins.

The aim of the present study was to purify the common native carp growth hormone (ncGH), produce monoclonal antibodies (mAbs) to common native carp growth hormone (ncGH), and further enhance the sensitivity of enzyme-linked immunosorbent assays (ELISA) for ncGH. Additionally, we investigated changes in serum ncGH levels in carps raised in different environmental conditions. The recombinant grass carp (Ctenopharyngodon idella) growth hormone was purified and used as antigen to immunize the rabbit. The natural ncGH was isolated from the pituitaries of common carp. SDS-PAGE and Western blot utilizing the polyclonal anti-rgcGH antibody confirmed the purification of ncGH from pituitaries. Purified ncGH was then used as an immunogen in the B lymphocyte hybridoma technique. A total of 14 hybridoma cell lines (FMU-cGH 1–14) were established that were able to stably secrete mAbs against ncGH. Among them, eight clones (FMU-cGH1–6, 12 and 13) were successfully used for Western blot while nine clones (FMU-cGH 1–7, 9 and 10) were used in fluorescent staining and immunohistochemistry. Epitope mapping by competitive ELISA demonstrated that these mAbs recognized five different epitopes. A sensitive sandwich ELISA for detection of ncGH was developed using FMU-cGH12 as the coating mAb and FMU-cGH6 as the enzyme labeled mAb. This detection system was found to be highly stable and sensitive, with detection levels of 70 pg/mL. Additionally, we found that serum ncGH levels in restricted food group and in the net cage group increased 6.9-and 5.8-fold, respectively, when compared to controls, demonstrating differences in the GH stress response in common carp under different living conditions.

GFP has often been used as a marker of gene expression, protein localization in living and fixed tissues as well as for protein targeting in intact cells and organisms. Monitoring foreign protein expression via GFP fusion is also very appealing for bioprocess applications. Many cells, including bacterial, fungal, plant, insect and mammalian cells, can express recombinant GFP (rGFP) efficiently. Several methods and procedures have been developed to purify the rGFP or recombinant proteins fused with GFP tag. However, most current GFP purification methods are limited by poor yields and low purity. In the current study, we developed an improved purification method, utilizing a FMU-GFP.5 monoclonal antibody (mAb) to GFP together with a mAb-coupled affinity chromatography column. The method resulted in a sample that was highly pure (more than 97% homogeneity) and had a sample yield of about 90%. Moreover, the GFP epitope permitted the isolation of almost all the active recombinant target proteins fused with GFP, directly and easily, from the crude cellular sources. Our data suggests this method is more efficient than any currently available method for purification of GFP protein.

To achieve active tumor targeting and sequential release of 3 drugs to a tumor site in one nanoparticulate system, self-decomposable SiO2 nanoparticles modified by 3-aminopropyltriethoxysilane (APTS) as their inner structure were used to double load HCPT (in the NP core) and Dox (on the NP surface). Meanwhile, monoclonal antibodies (mAb198.3) against the FAT1 antigen and Bcl-2 siRNA were conjugated onto PEGylated Au-PEG-COOH nanoparticles. The obtained drug-loaded SiO2 nanoparticles were coated with the Au-PEG-mAb.198.3/siRNA nanoparticles through electrostatic interaction to form the SiO2@AuNP sequential drug delivery system, which featured the controlled and sequential release of siRNA, Dox and HCPT step by step to maximize its anticancer efficacy. The results revealed that the SiO2@AuNP sequential drug delivery system specifically targeted tumor cells and was internalize rapidly, followed by endosome escape and sequential drug release. Importantly, the sustainable release characteristics of SiO2 made the Tmax difference between HCPT and Dox approximately 8–12 h, and this enhanced the sensitizing efficiency of HCPT on Dox compared with co-administration. The in vivo antitumor results demonstrated that the tumor size after SiO2@AuNP treatment is 1/400 compared with the saline control group and approximately 1/40 of the HCPT/Dox co-treatment group without any noticeable systemic toxicity.

CD226, a member of cell adhesion molecules, has been widely studied in the immune system; however, its expression in the CNS remains unknown. In our present study, we detected CD226 mRNA and protein in the mouse hippocampus and cerebellum by RT-PCR and Western blotting, respectively. Immunohistochemical studies found that CD226 is primarily located in the hilus of the dentate gyrus and stratum lucidum aligned along the pyramidal cells in the hippocampal CA3 area, the interspaces of granular cells and the somata of the Purkinje cells in the cerebellar cortex during adulthood. Double-staining results revealed that CD226 co-localized well with synaptic marker proteins including synaptophysin, syntaxin and PSD-95. During postnatal development, CD226 could not be detected at its adult locations until postnatal day 12; however, it was temporally expressed in the somata of neighboring or distant nuclei associated with its adult location. These results showed the diverse localization of CD226 in the mouse hippocampus and cerebellum for the first time and suggested its potential role in the CNS.