BD 3 Human

Beta Defensin-3 Human Recombinant
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Description

Introduction to BD-3 Human

BD-3 (Beta-defensin 3), also known as DEFB103 or hBD-3, is a 45-amino-acid cationic peptide belonging to the β-defensin family. It plays a critical role in innate immunity, particularly at epithelial surfaces and in leukocytes, where it exhibits broad-spectrum antimicrobial activity against bacteria, fungi, and viruses . Structurally, BD-3 contains three disulfide bonds (Cys1–Cys5, Cys2–Cys4, Cys3–Cys6) that stabilize its β-sheet structure, enabling membrane interaction and microbial disruption .

Antimicrobial Efficacy

PathogenMIC (μg/ml)MechanismSource
S. aureus5–12Membrane disruption
E. coli1–5C-terminal charge-mediated lysis
C. albicans15–17N-terminal interaction with fungal membranes
P. aeruginosa1–4High-salt resistance

Key Findings

  • Salt Resistance: BD-3 retains activity in physiological salt concentrations, unlike other β-defensins .

  • Synergy with Host Proteins: Disrupts bacterial cell wall biosynthesis in Staphylococcus spp. .

Immunomodulatory Roles

Beyond antimicrobial activity, BD-3 modulates immune responses:

  • TLR9 Activation: Enhances bacterial DNA recognition in dendritic cells, amplifying IFN-α and IL-6 production .

  • Antiviral Effects: Inhibits HIV, HSV, and influenza via CD98 downregulation .

Immunomodulatory Mechanisms

FunctionPathway/TargetOutcomeSource
TLR9 SensitizationBacterial DNA uptake in pDCsIncreased IFN-α, CXCL10
CD98 BindingReceptor internalizationReduced viral entry
ChemoattractionRecruitment of T cells and dendritic cellsEnhanced immune surveillance

Research Findings and Derivatives

Studies highlight BD-3’s structural adaptability and therapeutic potential:

  • Linear Derivatives: C-terminal peptides (e.g., CHRG01) show enhanced E. coli activity (LC90 = 1 μg/ml) .

  • γ-Core Isolation: Retains antibacterial and antiviral efficacy, suggesting modular therapeutic designs .

Derivative Performance

PeptideNet ChargeTarget PathogenActivity (LC90, μg/ml)Source
Native BD-3+11S. aureus12
CHRG01+8E. coli1
N-Terminal Deletion+7C. albicans15

Applications and Therapeutic Potential

BD-3 is being explored in:

  • Wound Healing: Promotes keratinocyte migration and angiogenesis .

  • Vaccine Adjuvants: Enhances TLR9-mediated responses to DNA vaccines .

  • Topical Therapies: Recombinant BD-3 (e.g., CYT-461) is produced in E. coli for clinical testing .

Challenges and Advances

  • Production: Codon optimization and fusion tags improve recombinant yields .

  • Toxicity: No significant hemolysis observed at therapeutic doses .

Product Specs

Introduction
Defensins are a family of antimicrobial and cytotoxic peptides produced by neutrophils. These peptides share high sequence similarity. This gene encodes for beta-defensin 103A, a protein with broad-spectrum antimicrobial activity that plays a crucial role in the innate immune response of epithelial cells.
Description
Recombinant Human Beta-Defensin 3, expressed in E. coli, is a single, non-glycosylated polypeptide chain consisting of 45 amino acids with a molecular weight of 5161.2 Daltons. The purification process of BD-3 involves proprietary chromatographic methods.
Physical Appearance
Sterile Filtered Lyophilized (Freeze-dried) Powder
Formulation
The HBD-3 was lyophilized without the addition of any excipients.
Solubility
Reconstitute the lyophilized Beta Defensin-3 in sterile 18 megaohm-cm H2O to a concentration of at least 100 µg/ml. This solution can be further diluted in other aqueous solutions.
Stability
Lyophilized Beta Defensin-3 Recombinant remains stable at room temperature for 3 weeks. However, it is recommended to store it desiccated below -18°C. Upon reconstitution, BD-3 should be stored at 4°C for a period of 2-7 days. For long-term storage, store below -18°C. Avoid repeated freeze-thaw cycles.
Purity
Purity exceeds 95.0% as determined by (a) Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) analysis and (b) Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis.
Synonyms
HBD3, HBP3, DEFB3, HBD-3, HBP-3, DEFB103.
Source
Escherichia Coli.
Amino Acid Sequence
GIINTLQKYY CRVRGGRCAV LSCLPKEEQI GKCSTRGRKC CRRKK.

Q&A

What is the BD CBA Human IL-3 Flex Set and what are its primary research applications?

The BD Cytometric Bead Array (CBA) Human IL-3 Flex Set is a specialized bead-based immunoassay designed for measuring human interleukin-3 (IL-3) in various biological samples including serum, plasma, and cell culture supernatants. This technology allows researchers to quantitatively assess IL-3 cytokine expression, which plays crucial roles in hematopoiesis and immune regulation .

The primary research applications include:

  • Immunological profiling in various disease states

  • Cytokine expression analysis in inflammatory conditions

  • Hematopoietic stem cell research

  • Investigation of immune signaling pathways

  • Monitoring cellular responses to experimental treatments

This technology is particularly valuable when researchers need to analyze multiple analytes simultaneously within limited sample volumes, offering higher throughput than traditional ELISA methods while maintaining comparable sensitivity and specificity .

How does sample multiplexing work in BD Single-Cell Multiomics studies?

Sample multiplexing in BD Single-Cell Multiomics studies enables researchers to analyze multiple biological samples simultaneously within a single experimental run. The methodology employs sample-specific tags that allow post-sequencing identification of the original sample source for each cell.

The process works through several key steps:

  • Each sample is labeled with a distinct Sample Tag from a BD Single-Cell Multiplexing Kit

  • Human and mouse sample kits provide up to 12 species-specific tags, while the flex sample kit offers up to 24 species and cell type agnostic tags

  • Multiple tagged samples are loaded into a BD Rhapsody Cartridge

  • During analysis, the pipeline automatically adds Sample Tag sequences to the FASTA reference file

  • Reads aligning to a Sample Tag sequence are used to identify the original sample for each putative cell

The sample determination algorithm identifies high-quality singlets, defined as putative cells where more than 75% of Sample Tag reads originate from a single tag. Low-level noise from other tags is expected due to PCR errors, sequencing errors, and residual labeling during cell preparation .

What are the limitations of using the BD CBA Human IL-3 Flex Set in multiplex assays?

When conducting multiplex assays, researchers should be aware of several important limitations of the BD CBA Human IL-3 Flex Set:

  • Multiplexing compatibility issues: The BD CBA Human IL-3 Flex Set exhibits significant background elevation when multiplexed with certain other assays such as the BD CBA Human IL-7, IL-8, IL-9, and IL-10 Flex Set assays. While this increased background reduces assay sensitivity, it does not otherwise affect IL-3 quantitation .

  • Incompatible combinations: The BD CBA Human IL-3 Flex Set cannot be used in the same assay well with specific BD CBA Human Soluble Protein Flex Set reagents, including:

    • BD CBA Human IL-12/IL-23p40 Flex Set (E5, catalog #560154)

    • BD CBA Human LT-α Flex Set (D5, catalog #560083)

    • BD CBA Human OSM Flex Set (D5, catalog #560084)

  • Sensitivity considerations: The elevated background in certain multiplex combinations affects the lower limit of detection, which researchers must account for when designing experiments requiring high sensitivity.

Understanding these limitations is essential for experimental design to prevent invalid results or data misinterpretation.

How can researchers optimize the sample determination algorithm in BD Rhapsody Analysis for accurate multiplex sample identification?

Optimizing the sample determination algorithm for accurate multiplex sample identification requires careful consideration of several technical parameters:

The algorithm identifies high-quality singlets where >75% of Sample Tag reads come from a single tag, with remaining counts considered noise. To enhance accuracy, researchers should:

  • Establish minimum read count thresholds: The minimum Sample Tag read count for positive identification should be defined as the lowest read count of a high-quality singlet for that particular Sample Tag .

  • Balance sensitivity and specificity: Adjust cutoff thresholds based on the distribution of read counts across all putative cells to minimize both false positives and false negatives.

  • Implement quality control measures:

    • Monitor the percentage of filtered reads aligning to sample tags

    • Track the percentage of sample tag reads assigned to putative cells

    • Analyze the distribution of reads per cell across different sample tags

    • Quantify multiplets and undetermined cells as quality metrics

  • Apply experimental validation: Verify algorithm performance using control samples with known cellular compositions to calibrate system parameters for specific experimental conditions.

Advanced researchers may further improve results by implementing custom computational approaches that integrate additional cellular characteristics beyond sample tag distributions.

What are the methodological considerations when using BD Single-Cell Multiomics for investigating bipolar disorder through patient-derived brain organoids?

Investigating bipolar disorder (BD) through patient-derived brain organoids using BD Single-Cell Multiomics technology requires sophisticated methodological considerations:

  • Experimental design complexities:

    • Control selection: Age/sex-matched healthy controls must be processed alongside BD patient samples

    • Temporal dynamics: Organoid development requires consistent timepoints for analysis across samples

    • Cellular heterogeneity: Accounting for variable neural cell type compositions between organoids

  • Technical workflow optimization:

    • Organoid dissociation protocols must preserve cell viability while achieving single-cell suspensions

    • Sample multiplexing strategies should balance batch effects against potential cross-contamination

    • Sequencing depth requirements are higher for detecting subtle transcriptomic differences in psychiatric disorders

  • Analytical approaches:

    • Cell type identification requires specialized reference atlases for brain organoid contexts

    • Trajectory analyses are essential for capturing neurodevelopmental abnormalities

    • Integration of transcriptomic and surface protein data enhances phenotypic characterization

  • Validation strategies:

    • Orthogonal validation using immunohistochemistry on intact organoids

    • Functional assays to correlate molecular findings with electrophysiological characteristics

    • Targeted drug perturbation to validate dysregulated pathways identified through multiomics

Recent advances in this field have enabled researchers to screen repurposed drug candidates using patient-derived brain organoids, potentially accelerating the development of more effective treatments for bipolar disorder .

How should researchers approach data analysis in BD Single-Cell Multiomics experiments?

Data analysis in BD Single-Cell Multiomics experiments requires a structured approach to extract meaningful biological insights from complex datasets:

  • Primary data processing:

    • Generate expression matrices using RSEC-adjusted (Recursive Substitution Error Correction) and DBEC-adjusted (Dual-Based Error Correction) molecule counts

    • Annotate BAM files to summarize pipeline results and facilitate downstream analyses

    • Filter low-quality cells based on established quality metrics

  • Dimensionality reduction and visualization:

    • Apply t-SNE (t-distributed Stochastic Neighbor Embedding) or UMAP for data visualization

    • Generate bioproduct expression plots showing distribution across identified cell clusters

    • Create interactive visualizations allowing exploration of individual markers

  • Cell type identification:

    • Implement automated cell type prediction algorithms

    • Refine annotations through manual expert curation based on canonical markers

    • Create cell type-specific expression profiles for downstream comparative analyses

  • Integration of multimodal data:

    • Correlate surface protein expression with transcriptomic profiles

    • Incorporate VDJ analysis for immune repertoire characterization when applicable

    • Develop integrated analyses that leverage both protein and RNA information

  • Statistical analysis approaches:

    • Employ differential expression testing accounting for multiple testing correction

    • Apply trajectory analysis to infer developmental or activation states

    • Utilize gene set enrichment analysis to identify relevant biological pathways

The BD Single-Cell Multiomics Bioinformatics toolkit provides specialized graphing functionality that helps researchers visualize complex relationships in their data, including single bioproduct expression distributions and immune cell type predictions .

What quality control metrics should be implemented when working with the BD CBA Human IL-3 Flex Set?

Implementing comprehensive quality control metrics is essential when working with the BD CBA Human IL-3 Flex Set to ensure reliable and reproducible results:

Quality Control ParameterAcceptance CriteriaTroubleshooting Approach
Standard Curve LinearityR² > 0.98Prepare fresh standards; check dilution accuracy
Assay Background<10% of lowest standardEnsure thorough washing; check for reagent contamination
Intra-assay CV<10%Improve pipetting technique; standardize incubation times
Inter-assay CV<15%Use consistent lot numbers; standardize protocols
Sample Recovery80-120%Check for matrix effects; consider sample dilution
Lower Limit of DetectionPer lot specificationsOptimize acquisition settings; increase acquisition events
Multiplex CompatibilitySee incompatibility listDesign panels avoiding known interference combinations

When implementing these controls, researchers should:

  • Include appropriate reference standards with each experimental run

  • Incorporate both positive and negative biological controls relevant to the experimental context

  • Validate assay performance using spike-in controls when analyzing complex biological matrices

  • Document all lot numbers, instrument settings, and experimental conditions to ensure reproducibility

For advanced research applications requiring highest sensitivity, consider validating critical findings with orthogonal methods such as ELISA or other cytokine detection platforms, especially when working near the assay's lower detection limit.

How can researchers integrate BD Single-Cell Multiomics data with other omics platforms for comprehensive disease mechanism studies?

Integrating BD Single-Cell Multiomics data with other omics platforms enables a holistic understanding of disease mechanisms through multi-level molecular profiling:

  • Multi-platform integration approaches:

    • Anchor-based integration: Identify shared features between datasets as integration anchors

    • Joint dimensionality reduction: Apply methods like MOFA+ (Multi-Omics Factor Analysis) to identify cross-platform variance components

    • Graph-based integration: Construct cellular networks incorporating interactions across omics layers

  • Cross-platform validation strategies:

    • Correlate single-cell transcriptomics with bulk RNA-sequencing from the same samples

    • Validate protein expression patterns using traditional immunoassays or mass spectrometry

    • Confirm genetic variants through targeted sequencing approaches

  • Functional annotation enrichment:

    • Map identified gene signatures to pathway databases (KEGG, Reactome)

    • Perform Gene Ontology analysis to characterize biological processes

    • Connect findings to relevant disease mechanisms through literature knowledge bases

  • Clinical data integration:

    • Associate molecular profiles with patient clinical characteristics

    • Identify biomarkers correlated with disease progression or treatment response

    • Develop predictive models incorporating both molecular and clinical variables

This integrated approach has proven particularly valuable in complex disorders like bipolar disorder, where the CircaVent project leverages multiomics approaches to examine the molecular mechanisms of common bipolar interventions and the underlying pathophysiology, ultimately aiming to develop improved therapeutic strategies .

What are the current computational challenges in analyzing BD 3 Human datasets, and what emerging solutions address these limitations?

Analysis of BD 3 Human datasets faces several computational challenges that researchers are addressing through innovative methodological approaches:

  • High-dimensional data complexity:

    • Challenge: BD Single-Cell Multiomics generates extremely high-dimensional datasets with thousands of measured parameters across thousands of cells

    • Solution: Advanced dimensionality reduction techniques beyond t-SNE, including UMAP and integration with reference atlases to anchor analysis in biological context

  • Batch effect management:

    • Challenge: Technical variation between experimental batches can mask biological signals

    • Solution: Deployment of sophisticated batch correction algorithms that preserve biological heterogeneity while minimizing technical artifacts

  • Rare cell type identification:

    • Challenge: Important cellular subpopulations may represent <1% of total cells

    • Solution: Implementation of over-clustering strategies followed by expert curation; development of sensitive anomaly detection algorithms

  • Multi-modal data integration:

    • Challenge: Combining protein, transcriptomic, and potentially genetic readouts into unified models

    • Solution: Development of multi-view learning approaches and weighted integration strategies that account for different noise characteristics across modalities

  • Scalability limitations:

    • Challenge: Computational infrastructure requirements grow exponentially with dataset size

    • Solution: Cloud-based analysis pipelines and distributed computing frameworks that parallelize computationally intensive tasks

In bipolar disorder research specifically, these computational approaches are being applied to understand the molecular mechanisms underlying BD phenotypes and the actions of existing therapeutic agents, potentially leading to more targeted therapeutic interventions .

What emerging applications of BD 3 Human technologies are transforming biomedical research?

BD 3 Human technologies are driving transformative advances across multiple domains of biomedical research:

  • Neurodegenerative and psychiatric disorder mechanisms:

    • Single-cell multiomics approaches now enable unprecedented resolution in characterizing cellular heterogeneity in complex brain disorders

    • The CircaVent project exemplifies this approach, using advanced BD technologies to investigate bipolar disorder mechanisms and screen potential therapeutic compounds

  • Immunological profiling and biomarker discovery:

    • BD CBA Human IL-3 Flex Set and related technologies allow comprehensive profiling of immune responses

    • Integration of surface protein and transcriptomic data provides deeper insights into immune cell subpopulations and their functional states

  • Therapeutic development pipelines:

    • High-throughput screening of drug candidates against patient-derived cells/organoids

    • Identification of responder populations through molecular phenotyping

    • Mechanistic studies of drug action at single-cell resolution

  • Multimodal disease characterization:

    • Integration of clinical data with molecular profiles to develop precision medicine approaches

    • Longitudinal monitoring of disease progression through minimally invasive biomarker assays

These emerging applications are particularly impactful in complex disorders like bipolar disorder, where technological advances are helping researchers overcome the "progress-hindering lack of understanding about the basic disease mechanisms," potentially transforming both scientific understanding and clinical approaches to treatment .

Product Science Overview

Structure and Characteristics

BD-3 is a 45-amino acid peptide with a molecular mass of approximately 5.2 kDa . It is characterized by its three intramolecular disulfide bonds, which distinguish it from alpha-defensins . The peptide is membrane-active and exhibits broad-spectrum antimicrobial activity against bacteria, viruses, and fungi .

Expression and Regulation

BD-3 is widely expressed in epithelial tissues, including the skin, respiratory tract, and gastrointestinal tract . It is produced by keratinocytes and airway epithelial cells and is upregulated in response to proinflammatory cytokines, microbial infections, and at the edges of skin wounds . This upregulation is part of the body’s natural defense mechanism to combat infections and promote healing.

Antimicrobial Activity

BD-3 exhibits strain-specific microbicidal activity and is effective against a broad range of pathogens, including Gram-positive and Gram-negative bacteria, as well as yeast . Its antimicrobial activity is measured by its ability to inhibit the growth of Escherichia coli, with an effective dose (ED50) ranging from 7.5 to 30 μg/mL .

Immunomodulatory Functions

In addition to its antimicrobial properties, BD-3 has several immunomodulatory functions. It can induce monocyte migration, activate mast cells, and increase vascular permeability . BD-3 also interacts with various receptors, including melanocortin receptors, cytokine receptors, and voltage-gated potassium channels . These interactions contribute to its role in inflammation and immune responses.

Recombinant Production

Recombinant human BD-3 is typically produced using Escherichia coli as the expression system . The recombinant protein is purified to a high degree of purity (>95%) and is available in both carrier-free and BSA-containing formulations . The carrier-free version is recommended for applications where the presence of BSA could interfere with experimental results .

Applications and Potential

BD-3 has promising applications in various fields, including medicine and biotechnology. Its broad-spectrum antimicrobial activity makes it a potential candidate for developing new antimicrobial therapies. Additionally, its immunomodulatory functions could be harnessed for treating inflammatory diseases and enhancing wound healing .

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