IL18R1 Antibody

What is IL18R1 and what is its primary function in immune response?

IL18R1 (Interleukin-18 Receptor 1) is a key component of the IL18 receptor complex responsible for binding the pro-inflammatory cytokine IL18, but not IL1A nor IL1B. It plays a crucial role in IL18-mediated interferon-gamma (IFNG) synthesis from T-helper 1 (Th1) cells and contributes to IL18-induced cytokine production. This receptor can function either independently or as a complex with SLC12A3 . IL18R1 is also known by several alternative names including CD218a, IL-18R-alpha, IL-1Rrp, and IL1R-rp, which reflects its discovery path and functional relationships within the interleukin receptor family .

What cell types express IL18R1 under normal physiological conditions?

IL18R1 expression varies across different immune cell populations. Studies using monoclonal antibodies against human IL-18R have demonstrated that most CD19+ B cells and a percentage of CD8+ T cells constitutively express IL18R1 under normal conditions . The expression pattern on other immune cells is more variable and often requires specific stimulation. For example, CD56+ NK cells typically require IL-12 treatment to induce substantial IL18R1 expression, while CD4+ T cells show weak IL18R1 expression with IL-12 treatment alone but moderate expression following phytohemagglutinin (PHA) stimulation . This differential expression pattern suggests cell type-specific regulation of IL18R1, which is important to consider when designing experiments targeting specific immune cell populations.

How do commercially available IL18R1 antibodies differ in their applications and specificities?

Available IL18R1 antibodies vary considerably in their formats, applications, and target species specificities. For instance, rabbit polyclonal antibodies like ab231565 are suitable for Western blot (WB) and immunohistochemistry on paraffin-embedded tissues (IHC-P) and react with mouse samples, making them appropriate for murine model studies . In contrast, rabbit recombinant monoclonal antibodies such as EPR26127-35 (ab308441) are optimized for immunocytochemistry/immunofluorescence (ICC/IF) and flow cytometry applications with human samples . When selecting an antibody, researchers should consider the specific experimental technique, target species, and cellular localization requirements. Validation data including predicted band sizes (e.g., 62 kDa for mouse IL18R1) should be consulted to verify antibody performance in the intended application .

How can neutralizing IL18R1 antibodies be used to investigate cytokine signaling networks?

Neutralizing IL18R1 antibodies provide powerful tools for dissecting the specific contributions of IL18 signaling within complex cytokine networks. Monoclonal antibodies like mAb No. 117-10C have been demonstrated to inhibit the binding of 125I-labeled human IL-18 to IL-18R-expressing cells and neutralize IL18-induced T helper 1 type cytokine (IFN-gamma and GM-CSF) production by ConA-stimulated peripheral blood mononuclear cells (PBMCs) . When designing experiments with neutralizing antibodies, researchers should include appropriate isotype controls and dose-response analyses to accurately interpret the specific effects of IL18 pathway inhibition. Additionally, considering the synergistic effects between IL18 and other cytokines like IL12, combinatorial treatments with multiple neutralizing antibodies can reveal the hierarchical organization and redundancy within inflammatory signaling pathways.

What considerations are important when designing IL18R1 immunodetection experiments in heterogeneous tissue samples?

Detecting IL18R1 in heterogeneous tissues presents several technical challenges that require careful experimental design. First, researchers must consider the differential expression of IL18R1 across various cell populations within the tissue. For example, immunohistochemical analysis of mouse colon and pancreas tissues shows cell type-specific IL18R1 expression patterns that require optimization of antibody concentration (typically 20-30 μg/ml for paraffin sections) . Second, appropriate positive and negative controls are essential—using tissues known to express IL18R1 (such as lymphoid organs) as positive controls and evaluating staining specificity with blocking peptides. Third, when quantifying IL18R1 expression in tissue samples, digital pathology tools like Quant Center 2.3 software can provide standardized analysis . Finally, researchers should complement protein detection with mRNA analysis to distinguish between transcriptional and post-transcriptional regulation of IL18R1 expression.

How does IL18R1 expression change in response to different cellular activation signals?

IL18R1 expression demonstrates complex, cell type-specific responsiveness to various activation signals. In CD56+ NK cells, IL-12 treatment preferentially induces IL18R1 expression regardless of costimulation with mitogens . For CD4+ T cells, IL-12 treatment induces weak IL18R1 expression, while PHA stimulation produces moderate expression . Interestingly, CD8+ T cells show resistance to IL18R1 induction by either IL-12 or PHA alone, requiring costimulation with both for optimal expression . The requirement for specific combination treatments suggests cell type-specific transcriptional regulation mechanisms and potential threshold effects in receptor expression. When investigating IL18R1 expression changes, researchers should consider time-course experiments to capture both early and late expression changes, and should evaluate both surface protein levels (by flow cytometry) and transcript abundance (by qPCR) to identify potential post-transcriptional regulation.

What are the optimal fixation and permeabilization methods for IL18R1 immunostaining?

Successful immunostaining for IL18R1 requires optimization of fixation and permeabilization protocols based on the specific application and cell/tissue type. For immunofluorescence analysis of human cell lines like HDLM-2 (Hodgkin lymphoma cells), 80% methanol fixation combined with 0.1% Tween-20 permeabilization has proven effective . For paraffin-embedded tissue sections, standard formalin fixation followed by heat-induced epitope retrieval is typically employed before IL18R1 antibody application . When optimizing protocols, researchers should test multiple conditions, considering that overfixation may mask epitopes while insufficient fixation may compromise cellular architecture. For flow cytometry applications, milder fixation (1-2% paraformaldehyde) and gentle permeabilization (0.1% saponin) often yield superior results by preserving surface epitopes. Regardless of the method chosen, validation with appropriate positive and negative controls is essential for confirming staining specificity.

What detection systems provide optimal sensitivity for IL18R1 Western blot analysis?

Western blot detection of IL18R1 requires careful optimization of detection systems to account for its moderate expression levels in many tissues. When using rabbit polyclonal antibodies like ab231565 at 2 μg/mL concentration, HRP-linked guinea pig anti-rabbit secondary antibodies at 1/1000 dilution have demonstrated good sensitivity for detecting the 62 kDa IL18R1 band in mouse pancreas and stomach lysates . Enhanced chemiluminescence (ECL) systems are commonly employed, but for tissues with lower IL18R1 expression, more sensitive detection methods such as fluorescent secondary antibodies or amplification systems may be required. Sample preparation is equally critical—using RIPA buffer with protease inhibitors and adequate sonication helps ensure complete protein extraction. Additionally, researchers should validate specificity by including positive controls (e.g., cell lines with confirmed IL18R1 expression) and negative controls (e.g., lysates from IL18R1 knockout cells where available).

How can flow cytometry protocols be optimized to accurately quantify IL18R1 expression on different immune cell populations?

Optimizing flow cytometry for IL18R1 detection requires careful consideration of several factors. First, panel design should include markers to clearly identify target populations (e.g., CD19 for B cells, CD4/CD8 for T cells, CD56 for NK cells) alongside IL18R1 staining . Second, titration of IL18R1 antibodies is essential—for recombinant monoclonal antibodies like ab308441, starting with manufacturer recommendations (e.g., 1/500 dilution) and testing a range around this value . Third, appropriate controls are critical: fluorescence minus one (FMO) controls help establish gating boundaries, while isotype controls confirm staining specificity. Fourth, when analyzing samples where IL18R1 expression might be induced (e.g., after cytokine stimulation), time-course experiments with multiple time points are recommended to capture expression dynamics. Finally, dual-parameter plots (e.g., IL18R1 vs. CD marker) enable visualization of differential expression across subpopulations, revealing biologically relevant patterns that might be missed in single-parameter analyses.

What experimental approaches can help elucidate the functional impact of IL18R1 in disease models?

Elucidating IL18R1's functional impact in disease requires multi-faceted experimental approaches. Gain-of-function and loss-of-function studies provide direct evidence of IL18R1's causal role—overexpression of IL18R1 in LUSC cells demonstrates its ability to inhibit cancer cell proliferation, migration, and invasion . Complementary approaches include CRISPR/Cas9-mediated knockout or siRNA-mediated knockdown to assess the consequences of IL18R1 deficiency. For in vivo studies, conditional knockout mouse models can reveal tissue-specific functions, while adoptive transfer experiments with IL18R1-deficient immune cells can demonstrate its role in immune responses. High-dimensional analyses like single-cell RNA sequencing provide insights into how IL18R1 expression varies across cell populations in complex tissues. Finally, unbiased screening approaches such as phosphoproteomic analysis after IL18 stimulation in IL18R1-sufficient versus IL18R1-deficient cells can identify downstream signaling pathways mediating IL18R1's biological effects.

How can researchers investigate the relationship between IL18R1 expression and immune cell infiltration in tumor microenvironments?

Investigating the relationship between IL18R1 and tumor immune infiltration requires integrated experimental approaches. Multiplex immunohistochemistry or immunofluorescence using IL18R1 antibodies alongside immune cell markers (CD8, CD4, CD56, etc.) allows spatial analysis of IL18R1 expression relative to immune infiltrates . Flow cytometry analysis of dissociated tumor tissues enables quantitative assessment of IL18R1 expression on specific immune cell subsets within the tumor microenvironment. Computational methods using gene expression data from public repositories (such as TCGA) can identify correlations between IL18R1 expression and immune signatures; for instance, in LUSC, IL18R1 expression correlates with stromal, immune, and estimate scores as well as with markers of T cells and cytotoxic cells . Functional validation through in vitro co-culture systems (e.g., cancer cells with immune cells in the presence or absence of IL18/IL18R1 blockade) can demonstrate causality in observed associations. Together, these approaches can reveal whether IL18R1 actively influences immune recruitment or merely reflects the presence of specific immune populations.

What is known about the competing endogenous RNA networks regulating IL18R1 expression?

Research has uncovered complex competing endogenous RNA (ceRNA) networks that regulate IL18R1 expression, particularly in cancer contexts. In lung squamous cell carcinoma, specific long non-coding RNAs (lncRNAs), including AC091563.1 and RBPMS-AS1, show positive correlations with IL18R1 expression . These lncRNAs are downregulated in LUSC tissues and their reduced expression associates with shorter disease-specific survival and cancer progression . Mechanistically, these lncRNAs potentially function as molecular sponges by competing with IL18R1 mRNA for binding to microRNAs, particularly miR-128-3p, which shows negative correlations with both IL18R1 and these lncRNAs . When designing experiments to investigate ceRNA networks, researchers should employ multiple approaches: RNA immunoprecipitation to confirm RNA-RNA interactions, luciferase reporter assays to validate miRNA binding sites, and gain/loss-of-function studies to establish the functional consequences of manipulating specific network components. Comprehensive understanding of these regulatory mechanisms may reveal new therapeutic targets that could modulate IL18R1 expression in disease contexts.

How does the IL18 receptor complex assembly occur and what role does IL18R1 play within this complex?

The IL18 receptor complex assembly involves coordinated interactions between multiple components, with IL18R1 playing a central role. IL18R1 (also known as IL-18Rα) functions as the primary ligand-binding component, specifically recognizing and binding the pro-inflammatory cytokine IL18, but not related cytokines like IL1A or IL1B . This initial binding event is followed by recruitment of the co-receptor IL-18RAP (IL-18Rβ), which does not bind IL18 directly but is essential for signal transduction. The assembled trimeric complex then initiates downstream signaling through the recruitment of MyD88 adapter protein and subsequent activation of NF-κB and MAPK pathways. Interestingly, IL18R1 can also contribute to IL18-induced cytokine production either independently or in complex with SLC12A3 , suggesting alternative signaling mechanisms. Research techniques to study receptor complex assembly include co-immunoprecipitation assays, proximity ligation assays to visualize protein interactions in situ, and FRET/BRET approaches to monitor real-time complex formation in living cells.

Table 1: Key Components of the IL18 Receptor Complex and Their Functions

How might single-cell analysis techniques advance our understanding of IL18R1 expression heterogeneity?

Single-cell analysis techniques offer unprecedented opportunities to dissect IL18R1 expression heterogeneity across diverse cell populations and disease states. Single-cell RNA sequencing (scRNA-seq) can reveal previously unrecognized IL18R1-expressing cell populations and identify co-expression patterns with other receptors and signaling molecules. This approach is particularly valuable given the known heterogeneity of IL18R1 expression across immune cell subsets, where expression can be constitutive in some cells (like CD19+ B cells) but stimulus-dependent in others (like CD8+ T cells) . Mass cytometry (CyTOF) using metal-conjugated IL18R1 antibodies enables simultaneous analysis of IL18R1 alongside 40+ other markers, providing comprehensive phenotyping of IL18R1+ cells. Single-cell proteomics approaches can detect post-translational modifications affecting IL18R1 function. When implementing these techniques, researchers should consider experimental design factors including sample preparation protocols that preserve cell viability and surface epitopes, appropriate panel design with validated antibodies, and computational analysis pipelines capable of identifying biologically meaningful patterns in high-dimensional data.

What potential exists for developing IL18R1-targeted therapeutics based on antibody engineering?

IL18R1-targeted therapeutics represent an emerging frontier with significant potential in cancer and inflammatory diseases. Given the tumor-suppressive properties observed with IL18R1 overexpression in lung cancer models , agonistic antibodies that mimic IL18 binding and activate IL18R1 signaling might potentially inhibit tumor growth. Conversely, in inflammatory conditions where IL18 signaling drives pathology, neutralizing antibodies blocking the IL18-IL18R1 interaction could provide therapeutic benefit. Beyond conventional antibodies, engineered formats offer expanded capabilities—bispecific antibodies could simultaneously target IL18R1 and another receptor like IL-12R to modulate synergistic cytokine responses; antibody-drug conjugates could deliver cytotoxic payloads specifically to IL18R1-expressing cells; and chimeric antigen receptor (CAR) T cells targeting IL18R1 might selectively eliminate cells overexpressing this receptor. When developing such therapeutics, researchers must address challenges including potential off-target effects on normal IL18R1-expressing immune cells, tissue penetration limitations, and the possibility of compensatory signaling mechanisms. Preclinical testing should therefore include comprehensive safety assessments in models that accurately recapitulate human IL18R1 expression patterns.

How can computational approaches help predict IL18R1 antibody epitopes and optimize antibody design?

Computational approaches are increasingly valuable for predicting IL18R1 antibody epitopes and optimizing antibody design for specific applications. Structural bioinformatics methods utilizing homology modeling and molecular dynamics simulations can predict IL18R1's three-dimensional structure and identify potential surface-exposed epitopes suitable for antibody targeting. Epitope mapping algorithms that integrate sequence conservation, hydrophilicity, and secondary structure predictions can prioritize regions likely to generate specific antibodies. Machine learning approaches trained on existing antibody-antigen interaction data can predict binding affinities and cross-reactivity profiles. For therapeutic antibody development, in silico humanization and immunogenicity prediction tools can minimize potential adverse immune responses. When applying these computational methods, researchers should validate predictions experimentally using techniques like peptide arrays, hydrogen-deuterium exchange mass spectrometry, or cryo-electron microscopy of antibody-antigen complexes. The integration of computational prediction with experimental validation creates an iterative optimization process that can significantly accelerate the development of high-performance IL18R1 antibodies for both research and potential therapeutic applications.