InVivoMAb anti-mouse IL-18
Product Details
The YIGIF74-1G7 monoclonal antibody reacts with mouse IL-18, an 18 kDa pro-inflammatory cytokine. IL-18 is expressed by activated macrophages, keratinocytes, Kupffer cells, intestinal epithelial cells, and osteoblasts. IL-18 has been shown to activate NF-ĪŗB, induce Fas ligand expression, induce both CC and CXC chemokine expression, and enhance the production of IFNĪ³ and GM-CSF.Specifications
| Isotype | Rat IgG2a, Īŗ |
|---|---|
| Recommended Isotype Control(s) | InVivoMAb rat IgG2a isotype control, anti-trinitrophenol |
| Recommended Dilution Buffer | InVivoPure pH 7.0 Dilution Buffer |
| Conjugation | This product is unconjugated. Conjugation is available via our Antibody Conjugation Services. |
| Immunogen | Not available or unknown |
| Reported Applications |
in vivo IL-18 neutralization in vitro IL-18 neutralization |
| Formulation |
PBS, pH 7.0 Contains no stabilizers or preservatives |
| Endotoxin |
<2EU/mg (<0.002EU/Ī¼g) Determined by LAL gel clotting assay |
| Purity |
>95% Determined by SDS-PAGE |
| Sterility | 0.2 Āµm filtration |
| Production | Purified from cell culture supernatant in an animal-free facility |
| Purification | Protein G |
| RRID | AB_2687719 |
| Molecular Weight | 150 kDa |
| Storage | The antibody solution should be stored at the stock concentration at 4Ā°C. Do not freeze. |
Recommended Products
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Recommended Isotype Control(s)
InVivoMAb rat IgG2a isotype control, anti-trinitrophenol
-
Recommended Dilution Buffer
InVivoPure pH 7.0 Dilution Buffer
in vivo IL-18 neutralization
Cohen, T. S., et al. (2018). "S. aureus Evades Macrophage Killing through NLRP3-Dependent Effects on Mitochondrial Trafficking" Cell Rep 22(9): 2431-2441. PubMed
Clinical severity of Staphylococcus aureus respiratory infection correlates with alpha toxin (AT) expression. AT activates the NLRP3 inflammasome; deletion of Nlrp3, or AT neutralization, protects mice from lethal S. aureus pneumonia. We tested the hypothesis that this protection is not due to a reduction in inflammasome-dependent cytokines (IL-1beta/IL-18) but increased bactericidal function of macrophages. In vivo, neutralization of AT or NLRP3 improved bacterial clearance and survival, while blocking IL-1beta/IL-18 did not. Primary human monocytes were used in vitro to determine the mechanism through which NLRP3 alters bacterial killing. In cells treated with small interfering RNA (siRNA) targeting NLRP3 or infected with AT-null S. aureus, mitochondria co-localize with bacterial-containing phagosomes. Mitochondrial engagement activates caspase-1, a process dependent on complex II of the electron transport chain, near the phagosome, promoting its acidification. These data demonstrate a mechanism utilized by S. aureus to sequester itself from antimicrobial processes within the cell.
in vivo IL-18 neutralization
Robinson, K. M., et al. (2018). "The inflammasome potentiates influenza/Staphylococcus aureus superinfection in mice" JCI Insight 3(7). PubMed
Secondary bacterial respiratory infections are commonly associated with both acute and chronic lung injury. Influenza complicated by bacterial pneumonia is an effective model to study host defense during pulmonary superinfection due to its clinical relevance. Multiprotein inflammasomes are responsible for IL-1Ī² production in response to infection and drive tissue inflammation. In this study, we examined the role of the inflammasome during viral/bacterial superinfection. We demonstrate that ASC-/- mice are protected from bacterial superinfection and produce sufficient quantities of IL-1Ī² through an apoptosis-associated speck-like protein containing CARD (ASC) inflammasome-independent mechanism. Despite the production of IL-1Ī² by ASC-/- mice in response to bacterial superinfection, these mice display decreased lung inflammation. A neutrophil elastase inhibitor blocked ASC inflammasome-independent production of IL-1Ī² and the IL-1 receptor antagonist, anakinra, confirmed that IL-1 remains crucial to the clearance of bacteria during superinfection. Delayed inhibition of NLRP3 during influenza infection by MCC950 decreases bacterial burden during superinfection and leads to decreased inflammatory cytokine production. Collectively, our results demonstrate that ASC augments the clearance of bacteria, but can also contribute to inflammation and mortality. ASC should be considered as a therapeutic target to decrease morbidity and mortality during bacterial superinfection.
in vivo IL-18 neutralization, in vitro IL-18 neutralization
Molgora, M., et al. (2017). "IL-1R8 is a checkpoint in NK cells regulating anti-tumour and anti-viral activity" Nature 551(7678): 110-114. PubMed
Interleukin-1 receptor 8 (IL-1R8, also known as single immunoglobulin IL-1R-related receptor, SIGIRR, or TIR8) is a member of the IL-1 receptor (ILR) family with distinct structural and functional characteristics, acting as a negative regulator of ILR and Toll-like receptor (TLR) downstream signalling pathways and inflammation. Natural killer (NK) cells are innate lymphoid cells which mediate resistance against pathogens and contribute to the activation and orientation of adaptive immune responses. NK cells mediate resistance against haematopoietic neoplasms but are generally considered to play a minor role in solid tumour carcinogenesis. Here we report that IL-1R8 serves as a checkpoint for NK cell maturation and effector function. Its genetic blockade unleashes NK-cell-mediated resistance to hepatic carcinogenesis, haematogenous liver and lung metastasis, and cytomegalovirus infection.
in vivo IL-18 neutralization
Chudnovskiy, A., et al. (2016). "Host-Protozoan Interactions Protect from Mucosal Infections through Activation of the Inflammasome" Cell 167(2): 444-456 e414. PubMed
While conventional pathogenic protists have been extensively studied, there is an underappreciated constitutive protist microbiota that is an integral part of the vertebrate microbiome. The impact of these species on the host and their potential contributions to mucosal immune homeostasis remain poorly studied. Here, we show that the protozoan Tritrichomonas musculis activates the host epithelial inflammasome to induce IL-18 release. Epithelial-derived IL-18 promotes dendritic cell-driven Th1 and Th17 immunity and confers dramatic protection from mucosal bacterial infections. Along with its role as a āprotisticā antibiotic, colonization with T. musculis exacerbates the development of T-cell-driven colitis and sporadic colorectal tumors. Our findings demonstrate a novel mutualistic host-protozoan interaction that increases mucosal host defenses at the cost of an increased risk of inflammatory disease.
- Mus musculus (Mouse),
Macrophages orchestrate elimination ofShigellafrom the intestinal epithelial cell niche via TLR-induced IL-12 and IFN-Ī³
In bioRxiv on 22 January 2025 by Eislmayr, K. D., Langner, C., et al.
- Mus musculus (Mouse),
- Immunology and Microbiology
Heightened innate immune state induced by viral vector leads to enhanced response to challenge and prolongs malaria vaccine protection.
In iScience on 20 December 2024 by GbƩdandƩ, K., Ibitokou, S. A., et al.
PubMed
Cytomegalovirus is a promising vaccine vector; however, mechanisms promoting CD4 TĀ cell responses to challenge, by CMV as a vector, are unknown. The ability of MCMV to prolong immunity generated by short-lived malaria vaccine was tested. MCMV provided non-specific protection to challenge with Plasmodium and increased interleukin-12 (IL-12) and CD8Ī±+ dendritic cell (DC) numbers through prolonged MCMV-dependent interferon gamma (IFN-Ī³) production. This late innate response to MCMV increased IL-12 upon challenge and increased the polyclonal CD4 effector TĀ cell response to Plasmodium, protecting in an IL-12-dependent manner. Although Plasmodium-vaccine-induced protection decayed by d200, MCMV restored protection through IFN-Ī³. Mechanistically, protection depended on MCMV-induced-IFN-Ī³ increasing CD8Ī±+ DCs and IL-12p40. MCMV expressing a Plasmodium epitope increased parasite-specific CD4 effector and effector memory TĀ cells persisting after malaria vaccination, both phenotypes reported to protect. Overall, enhanced innate cell status, a mechanism of heterologous protection by MCMV, led to a stronger TĀ cell response to challenge.
Damage-induced IL-18 stimulates thymic NK Cells limiting endogenous tissue regeneration
In bioRxiv on 30 September 2024 by Granadier, D., Cooper, K., et al.
- Endocrinology and Physiology
Circadian-clock-controlled endocrine and cytokine signals regulate multipotential innate lymphoid cell progenitors in the bone marrow.
In Cell Rep on 28 May 2024 by Liu, Q., Tabrez, S., et al.
PubMed
Innate lymphoid cells (ILCs), strategically positioned throughout the body, undergo population declines over time. A solution to counteract this problem is timely mobilization of multipotential progenitors from the bone marrow. It remains unknown what triggers the mobilization of bone marrow ILC progenitors (ILCPs). We report that ILCPs are regulated by the circadian clock to emigrate and generate mature ILCs in the periphery. We found that circadian-clock-defective ILCPs fail to normally emigrate and generate ILCs. We identified circadian-clock-controlled endocrine and cytokine cues that, respectively, regulate the retention and emigration of ILCPs at distinct times of each day. Activation of the stress-hormone-sensing glucocorticoid receptor upregulates CXCR4 on ILCPs for their retention in the bone marrow, while the interleukin-18 (IL-18) and RORĪ± signals upregulate S1PR1 on ILCPs for their mobilization to the periphery. Our findings establish important roles of circadian signals for the homeostatic efflux of bone marrow ILCPs.
- Mus musculus (Mouse),
- Immunology and Microbiology
Myeloid A20 is critical for alternative macrophage polarization and type-2 immune-mediated helminth resistance.
In Front Immunol on 29 April 2024 by Petta, I., Thorp, M., et al.
PubMed
Protective immunity against intestinal helminths requires induction of robust type-2 immunity orchestrated by various cellular and soluble effectors which promote goblet cell hyperplasia, mucus production, epithelial proliferation, and smooth muscle contractions to expel worms and re-establish immune homeostasis. Conversely, defects in type-2 immunity result in ineffective helminth clearance, persistent infection, and inflammation. Macrophages are highly plastic cells that acquire an alternatively activated state during helminth infection, but they were previously shown to be dispensable for resistance to Trichuris muris infection.
- Mus musculus (Mouse),
- Immunology and Microbiology
Low-Dose Chemotherapy Preferentially Shapes the Ileal Microbiome and Augments the Response to Immune Checkpoint Blockade by Activating AIM2 Inflammasome in Ileal Epithelial Cells.
In Adv Sci (Weinh) on 1 March 2024 by Pu, C., Li, Y., et al.
PubMed
Intervention of the gut microbiome is a promising adjuvant strategy in cancer immunotherapy. Chemotherapeutic agents are recognized for their substantial impacts on the gut microbiome, yet their therapeutic potential as microbiome modulators remains uncertain, due to the complexity of microbiome-host-drug interactions. Here, it is showed that low-dose chemotherapy preferentially shapes the ileal microbiome to augment the extraintestinal immune response to anti-programmed death-1 (anti-PD-1) therapy without causing intestinal toxicity. Mechanistically, low-dose chemotherapy causes DNA damage restricted to highly-proliferative ileal epithelial cells, resulting in the accumulation of cytosolic dsDNA and the activation of the absent in melanoma 2 (AIM2) inflammasome. AIM2-dependent IL-18 secretion triggers the interplay between proximal Th1 cells and Paneth cells in ileal crypts, impairing the local antimicrobial host defense and resulting in ileal microbiome change. Intestinal epithelium-specific knockout of AIM2 in mice significantly attenuates CPT-11-caused IL-18 secretion, Paneth cell dysfunction, and ileal microbiome alteration. Moreover, AIM2 deficiency in mice or antibiotic microbial depletion attenuates chemotherapy-augmented antitumor responses to anti-PD1 therapy. Collectively, these findings provide mechanistic insights into how chemotherapy-induced genomic stress is transduced to gut microbiome change and support the rationale of applying low-dose chemotherapy as a promising adjuvant strategy in cancer immunotherapy with minimal toxicity.
- Mus musculus (Mouse),
- Immunology and Microbiology
A pairwise cytokine code explains the organism-wide response to sepsis.
In Nat Immunol on 1 February 2024 by Takahama, M., Patil, A., et al.
PubMed
Sepsis is a systemic response to infection with life-threatening consequences. Our understanding of the molecular and cellular impact of sepsis across organs remains rudimentary. Here, we characterize the pathogenesis of sepsis by measuring dynamic changes in gene expression across organs. To pinpoint molecules controlling organ states in sepsis, we compare the effects of sepsis on organ gene expression to those of 6 singles and 15 pairs of recombinant cytokines. Strikingly, we find that the pairwise effects of tumor necrosis factor plus interleukin (IL)-18, interferon-gamma or IL-1Ī² suffice to mirror the impact of sepsis across tissues. Mechanistically, we map the cellular effects of sepsis and cytokines by computing changes in the abundance of 195 cell types across 9 organs, which we validate by whole-mouse spatial profiling. Our work decodes the cytokine cacophony in sepsis into a pairwise cytokine message capturing the gene, cell and tissue responses of the host to the disease.
- Immunology and Microbiology
Fusobacterium nucleatum infection activates the noncanonical inflammasome and exacerbates inflammatory response in DSS-induced colitis.
In Eur J Immunol on 1 November 2023 by Boonyaleka, K., Okano, T., et al.
PubMed
Caspase activation results in pyroptosis, an inflammatory cell death that contributes to several inflammatory diseases by releasing inflammatory cytokines and cellular contents. Fusobacterium nucleatum is a periodontal pathogen frequently detected in human cancer and inflammatory bowel diseases. Studies have reported that F. nucleatum infection leads to NLRP3 activation and pyroptosis, but the precise activation process and disease association remain poorly understood. This study demonstrated that F. nucleatum infection exacerbates acute colitis in mice and activates pyroptosis through caspase-11-mediated gasdermin D cleavage in macrophages. Furthermore, F. nucleatum infection in colitis mice induces the enhancement of IL-1āŗ secretion from the colon, affecting weight loss and severe disease activities. Neutralization of IL-1āŗ protects F. nucleatum infected mice from severe colitis. Therefore, F. nucleatum infection facilitates inflammation in acute colitis with IL-1āŗ from colon tissue by activating noncanonical inflammasome through gasdermin D cleavage.
- Mus musculus (Mouse),
- Immunology and Microbiology
Myeloid A20 is critical for type-2 immune mediated helminth resistance
In bioRxiv on 7 September 2023 by Petta, I., Thorp, M., et al.
- Immunology and Microbiology
A cytotoxic T cell inspired oncolytic nanosystem promotes lytic cell death by lipid peroxidation and elicits antitumor immune responses.
In Nat Commun on 6 September 2023 by Zuo, Z., Yin, H., et al.
PubMed
Lytic cell death triggers an antitumour immune response. However, cancer cells evade lytic cell death by several mechanisms. Moreover, a prolonged and uncontrolled immune response conversely leads to T-cell exhaustion. Therefore, an oncolytic system capable of eliciting an immune response by killing cancer cells in a controlled manner is needed. Here, we establish a micro-scale cytotoxic T-cell-inspired oncolytic system (TIOs) to precisely lyse cancer cells by NIR-light-controlled lipid peroxidation. Our TIOs present antigen-based cell recognition, tumour-targeting and catalytic cell-lysis ability; thus, the TIOs induce oncolysis in vivo. We apply TIOs to preclinical cancer models, showing anti-tumor activity with negligible side-effects. Tumour regression is correlated with a T-cell based anti-tumour immune response and TIOs also improve responses to anti-PD-1 therapy or STING activation. Our study provides insights to design oncolytic systems for antitumour immunity. Moreover, activation of STING can reverse T-cell exhaustion in oncolysis.
- Mus musculus (Mouse),
- Cancer Research,
- Immunology and Microbiology
Re-education of myeloid immune cells to reduce regulatory T cell expansion and impede breast cancer progression
In bioRxiv on 14 August 2023 by Gamage, H. E. V., Shahoei, S. H., et al.
- Immunology and Microbiology
Organism-Wide Analysis of Sepsis Reveals Mechanisms of Systemic Inflammation
In bioRxiv on 2 February 2023 by Takahama, M., Patil, A., et al.
- Western Blotting,
- Mus musculus (Mouse),
- Immunology and Microbiology
Alveolar macrophages instruct CD8+ T cell expansion by antigen cross-presentation in lung.
In Cell Rep on 13 December 2022 by Kawasaki, T., Ikegawa, M., et al.
PubMed
Lung CD8+ memory TĀ cells play central roles in protective immunity to respiratory viruses, such as influenza A virus (IAV). Here, we find that alveolar macrophages (AMs) function as antigen-presenting cells that support the expansion of lung CD8+ memory TĀ cells. Intranasal antigen administration to mice subcutaneously immunized with antigen results in a rapid expansion of antigen-specific CD8+ TĀ cells in the lung, which is dependent on antigen cross-presentation by AMs. AMs highly express interleukin-18 (IL-18), which mediates subsequent formation of CD103+CD8+ resident memory T (TRM) cells in the lung. In a mouse model of IAV infection, AMs are required for expansion of virus-specific CD8+ TĀ cells and CD103+CD8+ TRM cells and inhibiting virus replication in the lungs during secondary infection. These results suggest that AMs instruct a rapid expansion of antigen-specific CD8+ TĀ cells in lung, which protect the host from respiratory virus infection.
- Mus musculus (Mouse)
Integrated proteomic and transcriptomic landscape of macrophages in mouse tissues.
In Nat Commun on 30 November 2022 by Qie, J., Liu, Y., et al.
PubMed
Macrophages are involved in tissue homeostasis and are critical for innate immune responses, yet distinct macrophage populations in different tissues exhibit diverse gene expression patterns and biological processes. While tissue-specific macrophage epigenomic and transcriptomic profiles have been reported, proteomes of different macrophage populations remain poorly characterized. Here we use mass spectrometry and bulk RNA sequencing to assess the proteomic and transcriptomic patterns, respectively, of 10 primary macrophage populations from seven mouse tissues, bone marrow-derived macrophages and the cell line RAW264.7. The results show distinct proteomic landscape and protein copy numbers between tissue-resident and recruited macrophages. Construction of a hierarchical regulatory network finds cell-type-specific transcription factors of macrophages serving as hubs for denoting tissue and functional identity of individual macrophage subsets. Finally, Il18 is validated to be essential in distinguishing molecular signatures and cellular function features between tissue-resident and recruited macrophages in the lung and liver. In summary, these deposited datasets and our open proteome server ( http://macrophage.mouseprotein.cn ) integrating all information will provide a valuable resource for future functional and mechanistic studies of mouse macrophages.
- Immunology and Microbiology
Excessive IL-10 and IL-18 trigger hemophagocytic lymphohistiocytosis-like hyperinflammation and enhanced myelopoiesis.
In J Allergy Clin Immunol on 1 November 2022 by Tang, Y., Xu, Q., et al.
PubMed
Hyperinflammation is a life-threatening condition associated with various clinical disorders characterized by excessive immune activation and tissue damage. Multiple cytokines promote the development of hyperinflammation; however, the contribution of IL-10 remains unclear despite emerging speculations for a pathological role. Clinical observations from hemophagocytic lymphohistiocytosis (HLH), a prototypical hyperinflammatory disease, suggest that IL-18 and IL-10 may collectively promote the onset of a hyperinflammatory state.
- Immunology and Microbiology,
- Mus musculus (Mouse)
Newly recruited intraepithelial Ly6A+CCR9+CD4+ T cells protect against enteric viral infection.
In Immunity on 12 July 2022 by Parsa, R., London, M., et al.
PubMed
The intestinal epithelium comprises the body's largest surface exposed to viruses. Additionally, the gut epithelium hosts a large population of intraepithelial T lymphocytes, or IELs, although their role in resistance against viral infections remains elusive. By fate-mapping TĀ cells recruited to the murine intestine, we observed an accumulation of newly recruited CD4+ TĀ cells after infection with murine norovirus CR6 and adenovirus type-2 (AdV), but not reovirus. CR6- and AdV-recruited intraepithelial CD4+ TĀ cells co-expressed Ly6A and chemokine receptor CCR9, exhibited T helper 1 and cytotoxic profiles, and conferred protection against AdV inĀ vivo and in an organoid model in an IFN-Ī³-dependent manner. Ablation of the TĀ cell receptor (TCR) or the transcription factor ThPOK in CD4+ TĀ cells prior to AdV infection prevented viral control, while TCR ablation during infection did not impact viral clearance. These results uncover a protective role for intraepithelial Ly6A+CCR9+CD4+ TĀ cells against enteric adenovirus.
- In vivo experiments,
- Mus musculus (Mouse),
- Immunology and Microbiology
Enterocyte-innate lymphoid cell crosstalk drives early IFN-Ī³-mediated control of Cryptosporidium.
In Mucosal Immunol on 1 February 2022 by Gullicksrud, J. A., Sateriale, A., et al.
PubMed
The intestinal parasite, Cryptosporidium, is a major contributor to global child mortality and causes opportunistic infection in immune deficient individuals. Innate resistance to Cryptosporidium, which specifically invades enterocytes, is dependent on the production of IFN-Ī³, yet whether enterocytes contribute to parasite control is poorly understood. In this study, utilizing a mouse-adapted strain of C. parvum, we show that epithelial-derived IL-18 synergized with IL-12 to stimulate innate lymphoid cell (ILC) production of IFN-Ī³ required for early parasite control. The loss of IFN-Ī³-mediated STAT1 signaling in enterocytes, but not dendritic cells or macrophages, antagonized early parasite control. Transcriptional profiling of enterocytes from infected mice identified an IFN-Ī³ signature and enrichment of the anti-microbial effectors IDO, GBP, and IRG. Deletion experiments identified a role for Irgm1/m3 in parasite control. Thus, enterocytes promote ILC production of IFN-Ī³ that acts on enterocytes to restrict the growth of Cryptosporidium.
- Enzyme-linked immunosorbent assay,
- Mus musculus (Mouse),
- Immunology and Microbiology
Inflammasome activation leads to cDC1-independent cross-priming of CD8 T cells by epithelial cell-derived antigen.
In Elife on 23 December 2021 by Deets, K. A., Nichols Doyle, R., et al.
PubMed
The innate immune system detects pathogens and initiates adaptive immune responses. Inflammasomes are central components of the innate immune system, but whether inflammasomes provide sufficient signals to activate adaptive immunity is unclear. In intestinal epithelial cells (IECs), inflammasomes activate a lytic form of cell death called pyroptosis, leading to epithelial cell expulsion and the release of cytokines. Here, we employed a genetic system to show that simultaneous antigen expression and inflammasome activation specifically in IECs is sufficient to activate CD8+ T cells. By genetic elimination of direct T cell priming by IECs, we found that IEC-derived antigens were cross-presented to CD8+ T cells. However, cross-presentation of IEC-derived antigen to CD8+ T cells only partially depended on IEC pyroptosis. In the absence of inflammasome activation, cross-priming of CD8+ T cells required Batf3+ dendritic cells (conventional type one dendritic cells [cDC1]), whereas cross-priming in the presence of inflammasome activation required a Zbtb46+ but Batf3-independent cDC population. These data suggest the existence of parallel inflammasome-dependent and inflammasome-independent pathways for cross-presentation of IEC-derived antigens.
Neutrophil-specific gain-of-function mutations in Nlrp3 promote development of cryopyrin-associated periodic syndrome.
In J Exp Med on 4 October 2021 by Stackowicz, J., Gaudenzio, N., et al.
PubMed
Gain-of-function mutations in NLRP3 are responsible for a spectrum of autoinflammatory diseases collectively referred to as "cryopyrin-associated periodic syndromes" (CAPS). Treatment of CAPS patients with IL-1-targeted therapies is effective, confirming a central pathogenic role for IL-1Ī². However, the specific myeloid cell population(s) exhibiting inflammasome activity and sustained IL-1Ī² production in CAPS remains elusive. Previous reports suggested an important role for mast cells (MCs) in this process. Here, we report that, in mice, gain-of-function mutations in Nlrp3 restricted to neutrophils, and to a lesser extent macrophages/dendritic cells, but not MCs, are sufficient to trigger severe CAPS. Furthermore, in patients with clinically established CAPS, we show that skin-infiltrating neutrophils represent a substantial biological source of IL-1Ī². Together, our data indicate that neutrophils, rather than MCs, can represent the main cellular drivers of CAPS pathology.
- In vivo experiments,
- Mus musculus (Mouse),
- Cancer Research,
- Immunology and Microbiology
Adoptive immunotherapy with transient anti-CD4 treatment enhances anti-tumor response by increasing IL-18RĪ±hi CD8+ T cells.
In Nat Commun on 7 September 2021 by Kim, S. H., Cho, E., et al.
PubMed
Adoptive T cell therapy (ACT) requires lymphodepletion preconditioning to eliminate immune-suppressive elements and enable efficient engraftment of adoptively transferred tumor-reactive T cells. As anti-CD4 monoclonal antibody depletes CD4+ immune-suppressive cells, the combination of anti-CD4 treatment and ACT has synergistic potential in cancer therapy. Here, we demonstrate a post-ACT conditioning regimen that involves transient anti-CD4 treatment (CD4post). Using murine melanoma, the combined effect of cyclophosphamide preconditioning (CTXpre), CD4post, and ex vivo primed tumor-reactive CD8+ T-cell infusion is presented. CTXpre/CD4post increases tumor suppression and host survival by accelerating the proliferation and differentiation of ex vivo primed CD8+ T cells and endogenous CD8+ T cells. Endogenous CD8+ T cells enhance effector profile and tumor-reactivity, indicating skewing of the TCR repertoire. Notably, enrichment of polyfunctional IL-18RĪ±hi CD8+ T cell subset is the key event in CTXpre/CD4post-induced tumor suppression. Mechanistically, the anti-tumor effect of IL-18RĪ±hi subset is mediated by IL-18 signaling and TCR-MHC I interaction. This study highlights the clinical relevance of CD4post in ACT and provides insights regarding the immunological nature of anti-CD4 treatment, which enhances anti-tumor response of CD8+ T cells.