IL 1RA Antibody
Description
Molecular and Functional Overview of IL-1RA
IL-1RA is a 17–20 kDa protein encoded by the IL1RN gene, functioning as a competitive inhibitor of IL-1α and IL-1β by binding non-productively to the IL-1 receptor (IL-1R1) . Structurally, it shares a β-trefoil fold with IL-1 family cytokines but lacks receptor-activating capabilities due to divergent surface residues .
Key isoforms:
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Secreted IL-1RA (sIL-1RA): 17 kDa, produced by monocytes, macrophages, and neutrophils .
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Intracellular IL-1RA (icIL-1RA): 18 kDa, expressed in epithelial cells and fibroblasts .
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Hyperphosphorylated IL-1RA: A transient isoform observed in multisystem inflammatory syndrome in children (MIS-C), linked to autoantibody generation .
Role of IL-1RA Antibodies in Research and Pathology
IL-1RA antibodies are utilized for:
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Detection: Quantifying IL-1RA levels in biological samples via ELISA, Western blot (WB), or immunohistochemistry (IHC) .
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Functional studies: Neutralizing IL-1RA to investigate IL-1 signaling pathways .
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Autoantibody profiling: Identifying pathogenic anti-IL-1RA antibodies in autoimmune diseases .
Table 1: Clinical Prevalence of Anti-IL-1RA Autoantibodies
Autoantibody-Mediated Dysregulation
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Neutralization: Anti-IL-1RA IgG1/IgG4 autoantibodies form immune complexes with IL-1RA, blocking its ability to inhibit IL-1R1 signaling .
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Hyperphosphorylated IL-1RA: Observed in MIS-C, this isoform triggers autoantibody production, exacerbating IL-1β-driven inflammation .
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Therapeutic interference: In Still’s disease, autoantibodies correlate with reduced anakinra (recombinant IL-1RA) efficacy .
Therapeutic Applications and Challenges
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Anakinra: Recombinant IL-1RA used in rheumatoid arthritis and autoinflammatory syndromes .
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Autoantibody clearance: Plasmapheresis and B-cell depletion therapies show promise in neutralizing autoantibody-positive patients .
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Vaccine adjuvants: IL-1RA deficiency amplifies RNA vaccine reactogenicity, highlighting its role in controlling systemic inflammation .
Future Directions
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Biomarker development: Anti-IL-1RA autoantibodies as prognostic markers in MIS-C and IgG4-RD .
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Targeted therapies: Engineered IL-1RA variants with enhanced pharmacokinetics for chronic inflammation .
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Combination regimens: Co-administration of IL-1RA with anti-cytokine biologics to counteract autoantibody effects .
Product Specs
Q&A
How do researchers validate the specificity of IL-1RA antibodies for experimental applications?
Validation requires a multi-modal approach combining knockout controls, epitope characterization, and functional assays. For Western blotting, parallel analysis of wild-type and IL1RN-knockout cell lysates (e.g., A431 cells) confirms target specificity by demonstrating the absence of a ~18-20 kDa band in knockout samples . Epitope mapping using overlapping peptide arrays reveals whether antibodies target linear vs. conformational regions; anti-IL-1RA monoclonal antibodies like G4-21 predominantly bind peptide clusters RA-05 (aa 41-59) and RA-12 (aa 121-139), while polyclonal antibodies exhibit broader reactivity . Functional validation involves neutralization assays where pre-incubation of IL-1RA with test antibodies (5–2000 nM) prevents IL-1RA-mediated inhibition of IL-1β-induced NF-κB activation in HEK-Blue reporter cells .
Table 1: Validation Parameters for Common IL-1RA Antibodies
What experimental models are optimal for studying IL-1RA signaling modulation?
Primary human fibroblasts (e.g., MRC-5) and epithelial cells (A549) provide physiologically relevant systems for assessing IL-1RA's anti-inflammatory effects. In fibrotic models, co-stimulation with 0.5 nM IL-1α and patient-derived anti-IL-1RA IgG (1:10 plasma dilution) increases IL-6/IL-8 secretion by 3–5 fold compared to healthy controls . For in vivo studies, murine models expressing human IL1RN transgenes avoid cross-reactivity issues with species-specific antibodies.
How do anti-IL-1RA autoantibodies contribute to IgG4-RD pathogenesis?
Neutralizing autoantibodies against IL-1RA create a functional IL-1 signaling excess by blocking IL-1RA’s receptor antagonism. In IgG4-RD cohorts, 38% of patients exhibit plasma anti-IL-1RA reactivity via ELISA, with IgG4 being the predominant subclass (14.2% seropositivity) . These autoantibodies reduce IL-1RA’s inhibitory capacity by 54% in HEK-Blue assays, correlating with elevated fibrotic mediators (TGF-β1, COL1A1) in patient fibroblasts . Multi-spectral immunofluorescence of IgG4-RD lesions shows 2.3-fold higher IL-1RA+ cell density than Sjögren’s syndrome controls, suggesting local antigen availability drives autoantibody production .
Table 2: Prevalence of Anti-IL-1RA Autoantibodies in Disease Cohorts
What strategies resolve conflicting data on IL-1RA’s role as a prognostic biomarker?
Discrepancies arise from pre-analytical variables (e.g., plasma vs. serum), disease heterogeneity, and assay platform differences. In bermekimab trials, responders had lower baseline IL-1RA (843 vs. 1035 pg/mL, p=0.0092), but this association was absent in placebo arms . To harmonize findings:
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Standardize matrices: EDTA-plasma outperforms serum due to reduced platelet-derived IL-1RA release during clotting .
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Define disease endotypes: IgG4-RD patients with >20% IgG4+ plasma cells exhibit 4.2-fold higher anti-IL-1RA titers than IgG4-low subgroups .
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Multi-analyte profiling: Pair IL-1RA measurements with IL-1α/β ratios to account for ligand-receptor stoichiometry.
How can researchers optimize IL-1RA detection in complex biological samples?
Immunodepletion and selective epitope exposure improve assay sensitivity:
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Immunoaffinity chromatography: Pre-clear samples using protein A/G columns to remove interfering IgG4 autoantibodies .
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Heat-induced epitope retrieval (HIER): Boiling FFPE sections in citrate buffer (pH 6.0) increases IL-1RA antibody binding by 2.1-fold in IHC .
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Cross-validation: Align ELISA data (e.g., Invitrogen paired antibodies ) with MSD/U-PLEX platforms to control for matrix effects.
Product Science Overview
Interleukin-1 Receptor Antagonist (IL-1Ra) is a naturally occurring anti-inflammatory protein that plays a crucial role in regulating the immune response. It is part of the interleukin-1 (IL-1) cytokine family, which includes both pro-inflammatory and anti-inflammatory members. IL-1Ra specifically inhibits the activities of IL-1α and IL-1β by binding to their receptors without eliciting a signal, thereby preventing these cytokines from exerting their pro-inflammatory effects .
IL-1Ra is a 178-amino acid protein encoded by the IL1RN gene in humans. It exists in both secreted and intracellular forms, with the secreted form being the most studied. The protein functions by competitively inhibiting the binding of IL-1α and IL-1β to the interleukin-1 receptor (IL-1R), thus blocking the downstream signaling pathways that lead to inflammation .
IL-1Ra is essential for maintaining the balance between pro-inflammatory and anti-inflammatory signals in the body. It protects against excessive immune activation and uncontrolled systemic inflammation triggered by various stimuli, including pathogens . Dysregulation of IL-1Ra levels can lead to chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease .
Mouse anti-human IL-1Ra antibodies are monoclonal antibodies developed in mice that specifically target human IL-1Ra. These antibodies are used in research to study the role of IL-1Ra in various diseases and to develop potential therapeutic interventions. They are also employed in diagnostic assays to measure IL-1Ra levels in biological samples .
Research on IL-1Ra has led to significant advancements in understanding the mechanisms of inflammation and immune regulation. IL-1Ra has been explored as a therapeutic agent in treating various inflammatory conditions. For instance, Anakinra, a recombinant form of human IL-1Ra, is used clinically to treat rheumatoid arthritis and other inflammatory diseases .
In mouse models, IL-1Ra knockout mice have been used to study the effects of increased IL-1 signaling. These studies have shown that the absence of IL-1Ra leads to enhanced inflammatory responses and increased susceptibility to inflammatory diseases .
