IL 3 Antibody
Description
Definition and Biological Context
IL-3 Antibodies are immunoglobulins that target IL-3, a cytokine regulating hematopoiesis and immune responses, or its receptor subunit CD123 (IL-3Rα). They are classified into:
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Neutralizing antibodies: Block IL-3 signaling by preventing ligand-receptor binding .
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Diagnostic antibodies: Detect IL-3 in immunoassays like Western blot or immunohistochemistry .
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Therapeutic antibodies: Engineered to deplete CD123-expressing cells (e.g., leukemia stem cells) via antibody-dependent cellular cytotoxicity (ADCC) .
Inflammatory Bowel Disease (IBD)
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IL-3 neutralization exacerbates colitis in murine models, increasing CD4+ T cell infiltration and reactive oxygen species .
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Conversely, IL-3R signaling enhances regulatory T cell (Treg) retention in the colon, reducing inflammation via cytoskeletal remodeling .
Cancer Immunotherapy
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CSL362 reduced leukemic engraftment in mice by 60–80% through ADCC, with synergistic effects when combined with tyrosine kinase inhibitors .
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IL-3 antibody-treated tumors show increased CTL activity and basophil-derived IL-4, enhancing antitumor immunity .
Autoimmune Disorders
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Anti-IL-3 antibodies mitigate lupus nephritis in MLR/lpr mice by reducing IFNα production by plasmacytoid dendritic cells .
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In experimental autoimmune encephalomyelitis (EAE), IL-3 antibodies reduce CNS leukocyte infiltration by suppressing E-selectin expression .
Table 2: Therapeutic Efficacy in Leukemia Models
| Model | Antibody | Outcome | Mechanism |
|---|---|---|---|
| CML xenografts | CSL362 | 70% reduction in leukemic engraftment | ADCC via autologous NK cells |
| AML PDX | CSL362 | Prolonged survival (median 68 vs. 42 days) | CD123 targeting |
Challenges and Future Directions
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Dual roles in inflammation: IL-3 antibodies may exacerbate or ameliorate colitis depending on disease stage, necessitating context-specific dosing .
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Biomarker potential: Serum IL-3 levels correlate with colorectal cancer progression, but standardized assays for clinical use remain under development .
Product Specs
Q&A
Overview
This document synthesizes 20 critical research questions about interleukin-3 (IL-3) antibodies, stratified into basic and advanced tiers. It integrates experimental evidence from 6 peer-reviewed studies spanning neutralization kinetics, receptor cross-talk, and therapeutic applications in chronic inflammation/leukemia. Data are presented through comparative tables and methodological frameworks derived from primary literature.
What criteria define optimal IL-3 antibody selection for neutralization assays?
Key factors include:
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Epitope specificity: Antibodies targeting IL-3's receptor-binding domain (e.g., MAB403 vs. MAB203R ) exhibit distinct neutralization half-maximal inhibitory concentrations (ND₅₀). For murine systems, MAB403 achieves ND₅₀ = 0.05-0.15 µg/mL with 0.5 ng/mL IL-3 , while human IL-3 requires ND₅₀ = 0.03-0.08 µg/mL with 1.25 ng/mL IL-3 .
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Species cross-reactivity: Rat anti-mouse IL-3 antibodies (Clone MP28F8 ) show no cross-reactivity with human IL-3 due to <30% sequence homology .
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Validation controls: Include IL-3-dependent cell lines (NFS60 for mouse ; TF-1 for human ) and negative controls like stromal cell lines with altered EC₅₀ requirements .
Table 1: Neutralization Efficacy of Common IL-3 Antibodies
| Antibody Clone | Target Species | ND₅₀ Range (µg/mL) | Cell Model | Citation |
|---|---|---|---|---|
| MP28F8 | Mouse | 0.05–0.15 | NFS60 | |
| 4806R | Human | 0.03–0.08 | TF-1 | |
| M7B1-5.1-F9 | Mouse | 0.2–2.0 nM* | NFS60.8 |
*EC₅₀ for agonist activity in variant cell lines .
How do IL-3 antibodies modulate receptor signaling in proliferation assays?
IL-3 antibodies can act as agonists or antagonists depending on epitope engagement:
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Agonist antibodies (e.g., F9 ) mimic IL-3 by binding IL-3Rα, inducing tyrosine phosphorylation of STAT5 and ERK1/2 with EC₅₀ = 0.2–2.0 nM in wild-type NFS60 cells .
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Neutralizing antibodies block IL-3/IL-3R interaction, suppressing downstream pathways. For example, MAB403 reduces IL-3-induced NFS60 proliferation by 95% at 0.15 µg/mL .
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Dose-response validation: Always compare sigmoidal curves of IL-3 vs. antibody-mediated effects using Resazurin or MTT assays .
What controls are essential for IL-3 antibody specificity validation?
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Isotype-matched antibodies: Use non-targeting IgGs to rule out Fc-mediated effects .
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Receptor knockout models: IL-3Rα-deficient T cells (Il3r−/−) show abolished signaling, confirming target specificity .
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Cross-species testing: Human IL-3 antibodies should not react with mouse bone marrow progenitors .
How does IL-3 antibody-mediated receptor modulation influence Treg mechanobiology in colitis?
Mechanistic insights:
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IL-3R signaling in Tregs increases actin polymerization, reducing cellular deformability (Young’s modulus = 0.5 kPa vs. 0.3 kPa in Il3r−/− cells) and enhancing tissue retention .
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Experimental workflow:
Key data: Il3r−/− Tregs exhibit 40% higher mucosal retention due to altered cytoskeletal dynamics .
Can IL-3 receptor-targeting antibodies overcome cytokine-mediated TKI resistance in CML?
Therapeutic rationale:
Table 2: Efficacy of CSL362 in CML Models
| Parameter | CSL362 Monotherapy | CSL362 + TKI |
|---|---|---|
| Progenitor depletion | 45% | 80% |
| NK cell activation | 60% CD107a+ | 75% CD107a+ |
| IL-3 neutralization | IC₅₀ = 1.2 nM | IC₅₀ = 0.8 nM |
How do contradictory findings on IL-3 antibody agonist activity arise across studies?
Resolution strategies:
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Cell line variability: NFS60.8 subclones require 15-fold higher F9 antibody concentrations (EC₅₀ = 30 nM) due to altered receptor stoichiometry .
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Receptor density: Stromal cells express 50% fewer IL-3Rα subunits, reducing antibody binding avidity .
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Phosphoproteomic profiling: Always map tyrosine phosphorylation patterns (e.g., pSTAT5, pERK) to confirm signaling equivalence between IL-3 and antibody agonists .
What methodologies quantify IL-3 antibody effects on hematopoietic stem cell (HSC) differentiation?
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Colony-forming unit (CFU) assays:
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Single-cell RNA sequencing: Identifies IL-3 antibody-driven shifts in HSC transcriptional programs (e.g., MYC downregulation).
Methodological Best Practices
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Titration curves: Test IL-3 antibodies across 5-log concentrations (0.01–10 µg/mL) to capture biphasic effects .
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Kinetic analysis: Use SPR or BLI to measure binding affinity (KD ≤ 1 nM for therapeutic-grade antibodies) .
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In vivo validation: For colitis models, administer antibodies via intraperitoneal injection (5 mg/kg, 3x/week) and monitor via colonoscopy .
Product Science Overview
Interleukin-3 (IL-3) is a cytokine that plays a crucial role in the immune system by regulating the production, differentiation, and function of various blood cells. It is a member of the β common chain family of cytokines, which also includes interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF) . IL-3 is primarily produced by activated T cells, but it can also be produced by other immune cells such as monocytes, macrophages, and some non-immune cells like astrocytes and mesenchymal stem cells .
IL-3 exerts its function through a heterodimeric receptor composed of the IL-3 receptor α-chain (CD123) and the common receptor β-chain (CD131) . The α-chain (CD123) provides specificity for IL-3, while the β-chain (CD131) is essential for signaling and receptor assembly . In mice, there is an additional IL-3-specific β chain that shows strong homology with CD131 but differs in its ability to bind IL-3 directly . The interaction between IL-3 and its receptor leads to the activation of several downstream signaling pathways, including JAK2/STAT5, PI-3K/AKT, and MAPK .
IL-3 is involved in various biological processes, including:
- Hematopoiesis: IL-3 stimulates the proliferation and differentiation of hematopoietic stem and progenitor cells (HSPCs), leading to the production of various blood cell types .
- Immune Response: IL-3 plays a role in the immune response by regulating the function of immune cells such as basophils, eosinophils, mast cells, monocytes, macrophages, and dendritic cells .
- Inflammation: IL-3 can either promote or resolve inflammation depending on the type of disease, the course of inflammation, and the cells or tissues involved .
Mouse anti-human IL-3 antibodies are monoclonal antibodies produced in mice that specifically target human IL-3. These antibodies are used in various research and clinical applications to study the function of IL-3 and its role in different diseases. They can also be used to block the interaction between IL-3 and its receptor, thereby inhibiting IL-3-mediated signaling pathways .
Mouse anti-human IL-3 antibodies have several applications, including:
- Research: These antibodies are used in immunological research to study the role of IL-3 in various biological processes and diseases. They can be used in techniques such as flow cytometry, immunohistochemistry, and ELISA to detect and quantify IL-3 .
- Therapeutics: Targeting IL-3 or its receptor with monoclonal antibodies has potential therapeutic applications in treating diseases characterized by abnormal IL-3 activity, such as certain inflammatory and autoimmune disorders .
