G CSF Antibody
Description
Definition and Biological Context
G-CSF antibodies target the G-CSF cytokine () or its receptor (G-CSFR/CD114). G-CSF drives neutrophil differentiation, mobilizes hematopoietic stem cells (HSCs), and modulates immune tolerance . Antibodies against G-CSF are classified as:
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Neutralizing antibodies: Block G-CSF/G-CSFR interaction (e.g., therapeutic applications).
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Detection antibodies: Used in immunoassays (e.g., ELISA, flow cytometry) .
Types of G-CSF Antibodies
Therapeutic Applications
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Enhanced Myeloid Recovery: Pre-complexing G-CSF with anti-G-CSF monoclonal antibodies (mAbs) boosts neutrophil expansion by >100-fold compared to G-CSF alone, even post-chemotherapy .
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Stem Cell Mobilization: Combining motixafortide (CXCR4 inhibitor) with G-CSF enables 92.5% of multiple myeloma patients to collect ≥6 × 10⁶ CD34⁺ HSCs in two apheresis cycles vs. 26.2% with G-CSF alone .
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Autoimmune Disease: Anti-G-CSFR antibodies reduce joint inflammation in antibody-mediated arthritis without compromising antiviral immunity .
Mechanistic Insights
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G-CSF antibodies alter T cell polarization toward Th2 responses and promote regulatory T cell differentiation, suggesting utility in autoimmune diseases .
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Blocking G-CSFR suppresses CXCL12-CXCR4 axis disruption, reducing HSC mobilization .
Clinical Implications
Challenges and Considerations
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Immunogenicity: Anti-drug antibodies (ADAs) against therapeutic G-CSF may reduce efficacy or cause adverse effects, necessitating immunogenicity testing .
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Specificity: Cross-reactivity with murine or canine G-CSF occurs in some antibodies (e.g., AF-214-NA shows <30% cross-reactivity) .
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Dosing: Pegylated G-CSF (e.g., pegfilgrastim) reduces dosing frequency but may require re-administration in prolonged neutropenia .
Future Directions
Product Specs
Q&A
Q1: How do G-CSF/anti-G-CSF antibody complexes enhance therapeutic efficacy in preclinical models?
G-CSF/anti-G-CSF antibody complexes amplify biological activity by stabilizing the cytokine, prolonging its half-life, and enhancing receptor binding. Pre-association with anti-G-CSF monoclonal antibodies (e.g., clone BVD11-37G10) increases myeloid cell expansion by >100-fold compared to free G-CSF. For example, 0.015 μg of complexed G-CSF achieves effects equivalent to 1.5 μg of free G-CSF, enabling dose reduction while maintaining therapeutic potency . This approach is particularly effective in models requiring rapid neutrophil mobilization, such as bacterial infection or cytoreductive therapy recovery.
| Parameter | Free G-CSF | G-CSF/Ab Complex |
|---|---|---|
| Dose Required | 1.5 μg | 0.015 μg |
| Efficacy | Baseline | >100-fold improvement |
| Myeloid Cell Expansion | Moderate | Dramatic |
Q2: What experimental controls are critical when studying G-CSF receptor blockade?
When testing anti-G-CSF receptor antibodies (e.g., in arthritis models), include:
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Isotype-matched controls to rule out non-specific antibody effects.
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Cytokine-free vehicle controls to assess baseline neutrophil infiltration.
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Receptor occupancy assays to confirm antibody binding kinetics.
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Functional readouts (e.g., CXCR2/CD62L expression on neutrophils) to validate receptor modulation .
Q3: How to reconcile conflicting results on G-CSF’s role in inflammatory vs. protective immunity?
G-CSF’s dual role arises from context-dependent signaling:
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Inflammatory contexts (e.g., APLAID, arthritis): G-CSF drives neutrophil recruitment and proinflammatory cytokine production (IL-1β, IL-6) . Blockade reduces joint damage.
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Protective immunity (e.g., bacterial infection): G-CSF/Ab complexes enhance neutrophil-mediated pathogen clearance without compromising T-cell responses .
To resolve contradictions, assess:
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Cellular targets (neutrophils vs. myeloid progenitors).
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Tissue-specific signaling (e.g., joint vs. spleen).
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Temporal dynamics (acute vs. chronic inflammation).
Q4: What factors influence antibody specificity in G-CSF neutralization assays?
Neutralization efficacy depends on:
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Antibody isotype (e.g., polyclonal vs. monoclonal).
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Epitope binding (e.g., clone BVD11-37G10 targets G-CSF’s receptor-binding domain).
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Assay conditions (e.g., cell type: NFS-60 myeloid cells vs. primary neutrophils).
Neutralization dose (ND₅₀) varies by assay:
| Assay | ND₅₀ (ng/mL) | Source |
|---|---|---|
| NFS-60 proliferation | 8–48 | Recombinant G-CSF |
| In vivo myeloid expansion | 0.015 μg complex | Mouse models |
Q5: How to optimize G-CSF/Ab complex formation for in vivo studies?
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Molar ratio titration: Test 1:5 to 1:15 G-CSF:Ab ratios to maximize stability.
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Concentration-dependent efficacy: Validate using splenic myeloid cell counts (e.g., CD11b⁺Gr-1⁺ cells) .
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Route of administration: Intraperitoneal injection enhances bioavailability compared to subcutaneous.
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Therapeutic window: Monitor for neutrophil overaccumulation, which may impair T-cell responses.
Q6: What methodologies validate G-CSF receptor blockade in disease models?
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Flow cytometry: Assess CXCR2 downregulation and CD62L upregulation on neutrophils .
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qPCR: Measure IL-1β, IL-6, and KC transcripts in inflamed tissues.
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Histopathology: Quantify neutrophil infiltration (e.g., synovial joint sections).
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Functional assays: Test neutrophil chemotaxis (e.g., KC gradient migration).
Q7: How to validate anti-G-CSF antibody specificity in diverse cell lines?
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Western blot: Confirm detection of ~18–22 kDa G-CSF bands in lysates (e.g., K-562, HeLa) .
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Flow cytometry: Use intracellular staining to localize G-CSF in myeloid cells (e.g., K-562) .
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Neutralization assays: Test across species (e.g., human vs. mouse G-CSF) .
| Cell Line | WB Detection | FC Detection | Source |
|---|---|---|---|
| K-562 | + | + (Intra) | Proteintech |
| HeLa | + | – | Proteintech |
| MCF-7 | + | – | Proteintech |
Q8: What pitfalls occur when comparing monoclonal vs. polyclonal anti-G-CSF antibodies?
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Cross-reactivity: Polyclonal antibodies may bind non-specific epitopes.
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Neutralization potency: Monoclonals (e.g., BVD11-37G10) often show higher ND₅₀ specificity .
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Species specificity: Validate reactivity across human/mouse models.
Q9: How to design preclinical studies for G-CSF-targeted therapies in autoimmune vs. infectious diseases?
Autoimmune diseases (e.g., APLAID, arthritis):
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Target: G-CSF receptor (anti-G-CSFR mAb).
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Endpoints: Reduced neutrophil infiltration, cytokine levels (IL-1β, IL-6) .
Infectious diseases (e.g., Listeria):
Q10: What challenges limit clinical translation of G-CSF antibody therapies?
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Immunogenicity: Repeated administration of anti-G-CSF antibodies may induce anti-drug antibodies.
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Neutropenia risk: Sustained receptor blockade could impair emergency granulopoiesis.
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Disease heterogeneity: Optimal dosing may vary between inflammatory conditions (e.g., APLAID vs. RA).
Product Science Overview
Granulocyte Colony Stimulating Factor (G-CSF) is a glycoprotein that plays a crucial role in hematopoiesis, the process of forming blood cellular components. It specifically stimulates the bone marrow to produce granulocytes and stem cells and release them into the bloodstream. G-CSF is widely used in clinical settings to treat neutropenia, a condition characterized by an abnormally low count of neutrophils, which are a type of white blood cell essential for fighting infections .
G-CSF binds to its receptor (G-CSFR) on the surface of hematopoietic progenitor cells, leading to their proliferation and differentiation into neutrophils . This binding activates several intracellular signaling pathways, including the JAK/STAT, PI3K/AKT, and Ras/MAPK pathways, which are involved in cell survival, proliferation, and differentiation .
G-CSF is FDA-approved for several clinical applications, including:
- Treatment of Neutropenia: G-CSF is used to treat neutropenia in patients undergoing chemotherapy, bone marrow transplantation, or those with chronic neutropenia .
- Stem Cell Mobilization: It is used to mobilize hematopoietic stem cells from the bone marrow into the peripheral blood for collection and subsequent transplantation .
G-CSF has shown promise in various research and therapeutic areas beyond hematopoiesis:
- Neuroprotection: G-CSF displays neuroprotective properties and has been studied for its potential in treating neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and stroke .
- Anti-Apoptotic and Immunomodulatory Effects: G-CSF has anti-apoptotic and immunomodulatory properties, making it a candidate for treating inflammatory and autoimmune diseases .
