Listening to each other: Infectious disease and cancer immunology

Recent Advances in Immunotherapy for Bladder Cancer Treatment

Bladder cancer is one of the most common malignancies worldwide. Standard neoadjuvant or metastatic therapy used to be cisplatin-based chemotherapy, but many patients are ineligible due to age, renal impairment, or frailty. Checkpoint inhibitors (e.g., atezolizumab and pembrolizumab) enhance survival in cisplatin-ineligible patients. Originally approved as second-line therapy for patients after platinum-based chemotherapy, nivolumab was approved by the FDA for adjuvant therapy of high-risk muscle-invasive urothelial cancer following the Checkmate 274 trial. It is indicated for patients with resected disease or cisplatin ineligibility. Recent developments focused on the contribution of nivolumab to outcomes have been complemented by ongoing investigations on atezolizumab as a monotherapy or in combinations for muscle-invasive bladder cancer, providing further hope for improved control. This narrative review aims to clarify the current applications of immunotherapy in treating bladder cancer and to explore the future outlook based on ongoing clinical trials.

A Herpes Simplex Virus Type-1-Derived Influenza Vaccine Induces Balanced Adaptive Immune Responses and Protects Mice From Lethal Influenza Virus Challenge

Influenza virus is a major respiratory viral pathogen responsible for the deaths of hundreds of thousands worldwide each year. Current vaccines provide protection primarily by inducing strain-specific antibody responses with the requirement of a match between vaccine strains and circulating strains. It has been suggested that anti-influenza T-cell responses, in addition to antibody responses may provide the broadest protection against different flu strains. Therefore, to address this urgent need, it is desirable to develop a vaccine candidate with an ability to induce balanced adaptive immunity including cell mediated immune responses. Here, we explored the potential of VC2, a well-characterized Herpes Simplex Virus type 1 vaccine vector, as a live attenuated influenza vaccine candidate. We generated a recombinant VC2 virus expressing the influenza A hemagglutinin protein. We show that this virus is capable of generating potent and specific anti-influenza humoral and cell-mediated immune responses. We further show that a single vaccination with the VC2-derived influenza vaccine protects mice from lethal challenge with influenza virus. Our data support the continued development of VC2-derived influenza vaccines for protection of human populations from both seasonal and pandemic strains of influenza. Finally, our results support the potential of VC2-derived vaccines as a platform for the rapid development of vaccines against emerging and established pathogens, particularly respiratory pathogens.

Unraveling lipid and inflammation interplay in cancer, aging and infection for novel theranostic approaches

The synergistic relationships between Cancer, Aging, and Infection, here referred to as the CAIn Triangle, are significant determinants in numerous health maladies and mortality rates. The CAIn-related pathologies exhibit close correlations with each other and share two common underlying factors: persistent inflammation and anomalous lipid concentration profiles in the membranes of affected cells. This study provides a comprehensive evaluation of the most pertinent interconnections within the CAIn Triangle, in addition to examining the relationship between chronic inflammation and specific lipidic compositions in cellular membranes. To tackle the CAIn-associated diseases, a suite of complementary strategies aimed at diagnosis, prevention, and treatment is proffered. Our holistic approach is expected to augment the understanding of the fundamental mechanisms underlying these diseases and highlight the potential of shared features to facilitate the development of novel theranostic strategies.

Identification of new potent agonists for toll-like receptor 8 by virtual screening methods, molecular dynamics simulation, and MM-GBSA

Toll-like receptor 8 (TLR8), as an endosomal transmembrane receptor, plays a crucial role in the innate immune response to neoplasia and viruses. Previous studies have shown that TLR8 agonists e.g. Motolimod can be used to treat patients with last-stage cancer. In this study, in order to find new suitable ligands for TLR8, 16 PBD codes related to TLR8 complexes were collected to design the pharmacophore models using the Pharmit server. Then the PubChem, and ZINC databases were screened by them. Subsequently, the ADME-Tox features of the compounds were detected using FAF-Drugs4 and the selected compounds were docked to TLR8 (PDB: 3w3j). Molecular dynamics simulation was used to compare compounds with the best docking scores, with Motolimod in complex with TLR8. Finally, two compounds were identified, PubChem: 124126919 (A) and PubChem: 18559540 (B), each with advantages over Motolimod. As the RMSD results showed that compound A has very good flexibility, in terms of energy calculated using the MM-GBSA method, complex B and TLR8 showed the lowest energy level compared to the rest of the complexes. These observations suggest that these two compounds could be used as TLR8 agonists with the desired pharmacological features in future experimental studies.Communicated by Ramaswamy H. Sarma.

Combination strategies to durably suppress HIV-1: Soluble T cell receptors

Immunotherapeutic interventions to enhance natural HIV-specific CD8+ T cell responses, such as vaccination or adoptive T cell transfer, have been a major focus of HIV cure efforts. However, these approaches have not been effective in overcoming viral immune evasion mechanisms. Soluble T cell receptor (TCR) bispecifics are a new class of 'off-the-shelf' therapeutic designed to address these limitations. These biologics are built on the Immune mobilising monoclonal TCRs against X disease (ImmTAX) platform, which was pioneered in oncology and recently validated by the FDA's approval of tebentafusp for treatment of metastatic uveal melanoma. ImmTAV® are an application of this technology undergoing clinical development for the elimination of chronic viral infections. ImmTAV molecules comprise an affinity-enhanced virus-specific TCR fused to an anti-CD3 effector domain. Engineering of the TCR confers extraordinary specificity and affinity for cognate viral antigen and the anti-CD3 enables retargeting of non-exhausted cytolytic T cells, irrespective of their specificity. These features enable ImmTAV molecules to detect and kill infected cells, even when expressing very low levels of antigen, bypassing ineffective host immune responses. Furthermore, the modularity of the platform allows for engineering of TCRs that effectively target viral variants. In this review, we discuss the progress made in the development of ImmTAV molecules as therapeutics for functional cure of chronic hepatitis B and HIV, from concept to the clinic.

Utility of a Recombinant HSV-1 Vaccine Vector for Personalized Cancer Vaccines

Current approaches to cancer immunotherapy include immune checkpoint inhibitors, cancer vaccines, and adoptive cellular therapy. These therapies have produced significant clinical success for specific cancers, but their efficacy has been limited. Oncolytic virotherapy (OVT) has emerged as a promising immunotherapy for a variety of cancers. Furthermore, the unique characteristics of OVs make them a good choice for delivering tumor peptides/antigens to induce enhanced tumor-specific immune responses. The first oncolytic virus (OV) approved for human use is the attenuated herpes simplex virus type 1 (HSV-1), Talimogene laherparepvec (T-VEC) which has been FDA approved for the treatment of melanoma in humans. In this study, we engineered the recombinant oncolytic HSV-1 (oHSV) VC2-OVA expressing a fragment of ovalbumin (OVA) as a fusion protein with VP26 virion capsid protein. We tested the ability of VC2-OVA to act as a vector capable of stimulating strong, specific antitumor immunity in a syngeneic murine melanoma model. Therapeutic vaccination with VC2-OVA led to a significant reduction in colonization of tumor cells in the lungs of mice intravenously challenged B16cOVA cells. In addition, VC2-OVA induced a potent prophylactic antitumor response and extended survival of mice that were intradermally engrafted with B16cOVA tumors compared with mice immunized with control virus.

Current Progress and Future Perspectives of Immune Checkpoint in Cancer and Infectious Diseases

The inhibitory regulators, known as immune checkpoints, prevent overreaction of the immune system, avoid normal tissue damage, and maintain immune homeostasis during the antimicrobial or antiviral immune response. Unfortunately, cancer cells can mimic the ligands of immune checkpoints to evade immune surveillance. Application of immune checkpoint blockade can help dampen the ligands expressed on cancer cells, reverse the exhaustion status of effector T cells, and reinvigorate the antitumor function. Here, we briefly introduce the structure, expression, signaling pathway, and targeted drugs of several inhibitory immune checkpoints (PD-1/PD-L1, CTLA-4, TIM-3, LAG-3, VISTA, and IDO1). And we summarize the application of immune checkpoint inhibitors in tumors, such as single agent and combination therapy and adverse reactions. At the same time, we further discussed the correlation between immune checkpoints and microorganisms and the role of immune checkpoints in microbial-infection diseases. This review focused on the current knowledge about the role of the immune checkpoints will help in applying immune checkpoints for clinical therapy of cancer and other diseases.

Deciphering Human Leukocyte Antigen Susceptibility Maps From Immunopeptidomics Characterization in Oncology and Infections

Genetic variability across the three major histocompatibility complex (MHC) class I genes (human leukocyte antigen [HLA] A, B, and C) may affect susceptibility to many diseases such as cancer, auto-immune or infectious diseases. Individual genetic variation may help to explain different immune responses to microorganisms across a population. HLA typing can be fast and inexpensive; however, deciphering peptides loaded on MHC-I and II which are presented to T cells, require the design and development of high-sensitivity methodological approaches and subsequently databases. Hence, these novel strategies and databases could help in the generation of vaccines using these potential immunogenic peptides and in identifying high-risk HLA types to be prioritized for vaccination programs. Herein, the recent developments and approaches, in this field, focusing on the identification of immunogenic peptides have been reviewed and the next steps to promote their translation into biomedical and clinical practice are discussed.

New generation of DNA-based immunotherapy induces a potent immune response and increases the survival in different tumor models

BACKGROUND

Strategies to increase nucleic acid vaccine immunogenicity are needed to move towards clinical applications in oncology. In this study, we designed a new generation of DNA vaccines, encoding an engineered vesicular stomatitis virus glycoprotein as a carrier of foreign T cell tumor epitopes (plasmid to deliver T cell epitopes, pTOP). We hypothesized that pTOP could activate a more potent response compared with the traditional DNA-based immunotherapies, due to both the innate immune properties of the viral protein and the specific induction of CD4 and CD8 T cells targeting tumor antigens. This could improve the outcome in different tumor models, especially when the DNA-based immunotherapy is combined with a rational therapeutic strategy.

METHODS

The ability of pTOP DNA vaccine to activate a specific CD4 and CD8 response and the antitumor efficacy were tested in a B16F10-OVA melanoma (subcutaneous model) and GL261 glioblastoma (subcutaneous and orthotopic models).

RESULTS

In B16F10-OVA melanoma, pTOP promoted immune recognition by adequate processing of both MHC-I and MHC-II epitopes and had a higher antigen-specific cytotoxic T cell (CTL) killing activity. In a GL261 orthotopic glioblastoma, pTOP immunization prior to tumor debulking resulted in 78% durable remission and long-term survival and induced a decrease of the number of immunosuppressive cells and an increase of immunologically active CTLs in the brain. The combination of pTOP with immune checkpoint blockade or with tumor resection improved the survival of mice bearing, a subcutaneous melanoma or an orthotopic glioblastoma, respectively.

CONCLUSIONS

In this work, we showed that pTOP plasmids encoding an engineered vesicular stomatitis virus glycoprotein, and containing various foreign T cell tumor epitopes, successfully triggered innate immunity and effectively promoted immune recognition by adequate processing of both MHC-I and MHC-II epitopes. These results highlight the potential of DNA-based immunotherapies coding for viral proteins to induce potent and specific antitumor responses.

Emerging skin-targeted drug delivery strategies to engineer immunity: A focus on infectious diseases

INTRODUCTION

Infectious pathogens are global disrupters. Progress in biomedical science and technology has expanded the public health arsenal against infectious diseases. Specifically, vaccination has reduced the burden of infectious pathogens. Engineering systemic immunity by harnessing the cutaneous immune network has been particularly attractive since the skin is an easily accessible immune-responsive organ. Recent advances in skin-targeted drug delivery strategies have enabled safe, patient-friendly, and controlled deployment of vaccines to cutaneous microenvironments for inducing long-lived pathogen-specific immunity to mitigate infectious diseases, including COVID-19.

AREAS COVERED

This review briefly discusses the basics of cutaneous immunomodulation and provides a concise overview of emerging skin-targeted drug delivery systems that enable safe, minimally invasive, and effective intracutaneous administration of vaccines for engineering systemic immune responses to combat infectious diseases.

EXPERT OPINION

In-situ engineering of the cutaneous microenvironment using emerging skin-targeted vaccine delivery systems offers remarkable potential to develop diverse immunization strategies against pathogens. Mechanistic studies with standard correlates of vaccine efficacy will be important to compare innovative intracutaneous drug delivery strategies to each other and to existing clinical approaches. Cost-benefit analyses will be necessary for developing effective commercialization strategies. Significant involvement of industry and/or government will be imperative for successfully bringing novel skin-targeted vaccine delivery methods to market for their widespread use.

Novel Oncolytic Herpes Simplex Virus 1 VC2 Promotes Long-Lasting, Systemic Anti-melanoma Tumor Immune Responses and Increased Survival in an Immunocompetent B16F10-Derived Mouse Melanoma Model

Current oncolytic virotherapies possess limited response rates. However, when certain patient selection criteria are used, oncolytic virotherapy response rates have been shown to increase.

Oncolytic virotherapy (OVT) is now understood to be an immunotherapy that uses viral infection to liberate tumor antigens in an immunogenic context to promote the development of antitumor immune responses. The only currently FDA-approved oncolytic virotherapy, T-Vec, is a modified type 1 herpes simplex virus (HSV-1). While T-Vec is associated with limited response rates, its modest efficacy supports the continued development of novel OVT viruses. Herein, we test the efficacy of a recombinant HSV-1, VC2, as an OVT in a syngeneic B16F10-derived mouse model of melanoma. VC2 possesses mutations that block its ability to enter neurons via axonal termini. This greatly enhances its safety profile by precluding the ability of the virus to establish latent infection. VC2 has been shown to be a safe, effective vaccine against both HSV-1 and HSV-2 infection in mice, guinea pigs, and nonhuman primates. We found that VC2 slows tumor growth rates and that VC2 treatment significantly enhances survival of tumor-engrafted, VC2-treated mice over control treatments. VC2-treated mice that survived initial tumor engraftment were resistant to a second engraftment as well as colonization of lungs by intravenous introduction of tumor cells. We found that VC2 treatment induced substantial increases in intratumoral T cells and a decrease in immunosuppressive regulatory T cells. This immunity was critically dependent on CD8⁺ T cells and less dependent on CD4⁺ T cells. Our data provide significant support for the continued development of VC2 as an OVT for the treatment of human and animal cancers.

IMPORTANCE Current oncolytic virotherapies possess limited response rates. However, when certain patient selection criteria are used, oncolytic virotherapy response rates have been shown to increase. This, in addition to the increased response rates of oncolytic virotherapy in combination with other immunotherapies, suggests that oncolytic viruses possess significant therapeutic potential for the treatment of cancer. As such, it is important to continue to develop novel oncolytic viruses as well as support basic research into their mechanisms of efficacy. Our data demonstrate significant clinical potential for VC2, a novel type 1 oncolytic herpes simplex virus. Additionally, due to the high rates of survival and the dependence on CD8⁺ T cells for efficacy, our model will enable study of the immunological correlates of protection for VC2 oncolytic virotherapy and oncolytic virotherapy in general. Understanding the mechanisms of efficacious oncolytic virotherapy will inform the rational design of improved oncolytic virotherapies.

Medicinal Chemistry and Methodological Advances in the Development of Peptide-Based Vaccines

The evolution of rapidly proliferating infectious and tumorigenic diseases has resulted in an urgent need to develop new and improved intervention strategies. Among the many therapeutic strategies at our disposal, our immune system remains the gold-standard in disease prevention, diagnosis, and treatment. Vaccines have played an important role in eradicating or mitigating the spread of infectious diseases by bolstering our immunity. Despite their utility, the design and development of new, more effective vaccines remains a public health necessity. Peptide-based vaccines have been developed for a wide range of established and emerging infectious and tumorigenic diseases. New innovations in epitope design and selection, synthesis, and formulation as well as screening techniques against immunological targets have led to more effective peptide vaccines. Current and future work is geared toward the translation of peptide vaccines from preclinical to clinical utility.

KIR Variation in Iranians Combines High Haplotype and Allotype Diversity With an Abundance of Functional Inhibitory Receptors

Natural killer (NK) cells are innate lymphocytes that eliminate infected and transformed cells. They discriminate healthy from diseased tissue through killer cell Ig-like receptor (KIR) recognition of HLA class I ligands. Directly impacting NK cell function, KIR polymorphism associates with infection control and multiple autoimmune and pregnancy syndromes. Here we analyze KIR diversity of 241 individuals from five groups of Iranians. These five populations represent Baloch, Kurd, and Lur, together comprising 15% of the ethnically diverse Iranian population. We identified 159 KIR alleles, including 11 not previously characterized. We also identified 170 centromeric and 94 telomeric haplotypes, and 15 different KIR haplotypes carrying either a deletion or duplication encompassing one or more complete KIR genes. As expected, comparing our data with those representing major worldwide populations revealed the greatest similarity between Iranians and Europeans. Despite this similarity we observed higher frequencies of KIR3DL1^*001 in Iran than any other population, and the highest frequency of HLA-B^*51, a Bw4-containing allotype that acts as a strong educator of KIR3DL1^*001⁺ NK cells. Compared to Europeans, the Iranians we studied also have a reduced frequency of 3DL1^*004, which encodes an allotype that is not expressed at the NK cell surface. Concurrent with the resulting high frequency of strong viable interactions between inhibitory KIR and polymorphic HLA class I, the majority of KIR-A haplotypes characterized do not express a functional activating receptor. By contrast, the most frequent KIR-B haplotype in Iran expresses only one functional inhibitory KIR and the maximum number of activating KIR. This first complete, high-resolution, characterization of the KIR locus of Iranians will form a valuable reference for future clinical and population studies.

Immune-awakening revealed by peripheral T cell dynamics after one cycle of immunotherapy

Our understanding of how checkpoint inhibitors (CPI) affect T cell evolution is incomplete, limiting our ability to achieve full clinical benefit from these drugs. Here we analyzed peripheral T cell populations after one cycle of CPI and identified a dynamic awakening of the immune system revealed by T cell evolution in response to treatment. We sequenced T cell receptors (TCR) in plasma cell-free DNA (cfDNA) and peripheral blood mononuclear cells (PBMC) and performed phenotypic analysis of peripheral T cell subsets from metastatic melanoma patients treated with CPI. We found that early peripheral T cell turnover and TCR repertoire dynamics identified which patients would respond to treatment. Additionally, the expansion of a subset of immune-effector peripheral T cells we call TIE cells correlated with response. These events are prognostic and occur within 3 weeks of starting immunotherapy, raising the potential for monitoring patients responses using minimally invasive liquid biopsies."

Metabolic Control of Epigenetics and Its Role in CD8+ T Cell Differentiation and Function

Epigenetic programs that control posttranslational modifications of histone proteins and DNA itself tightly regulate transcriptional networks determining the identity and function of CD8⁺ T cells. Chromatin-modifying enzymes such as histone acetyltransferases and deacetylases, represent key molecular determinants of the epigenetic imprinting of CD8⁺ T cells. The functions of these enzymes highly depend on the availability of key products of cellular metabolism pathways such as acetyl-CoA, NAD (Nicotinamide adenine dinucleotide) and SEM (S-adenosylmethionine), suggesting that there is a close crosstalk between the metabolic and the epigenetic regulation of CD8⁺ T cells. In this review, we will discuss the metabolic regulation of CD8⁺ T cell epigenetics during activation and differentiation. We will furthermore summarize how metabolic signals from the tumor microenvironment (TME) shape the epigenetic landscape of CD8⁺ T cells to better understand the mechanism underlying CD8⁺ T cell exhaustion in anti-tumor and anti-viral immunity, which might help to overcome limitations of current CD8⁺ T cell-based therapies.

MDA-9/Syntenin: An emerging global molecular target regulating cancer invasion and metastasis

With few exceptions, metastasis is the terminal stage of cancer with limited therapeutic options. Metastasis consists of numerous phenotypic and genotypic alterations of cells that are directly and indirectly induced by multiple intrinsic (cellular) and extrinsic (micro-environmental) factors. To metastasize, a cancer cell often transitions from an epithelial to mesenchymal morphology (EMT), modifies the extracellular matrix, forms emboli and survives in the circulation, escapes immune surveillance, adheres to sites distant from the initial tumor and finally develops a blood supply (angiogenesis) and colonizes in a secondary niche (a micrometastasis). Scientific advances have greatly enhanced our understanding of the precise molecular and genetic changes, operating independently or collectively, that lead to metastasis. This review focuses on a unique gene, melanoma differentiation associated gene-9 (also known as Syntenin-1; Syndecan Binding Protein (sdcbp); mda-9/syntenin), initially cloned and characterized from metastatic human melanoma and shown to be a pro-metastatic gene. In the last two decades, our comprehension of the diversity of actions of MDA-9/Syntenin on cellular phenotype has emerged. MDA-9/Sytenin plays pivotal regulatory roles in multiple signaling cascades and orchestrates both metastatic and non-metastatic events. Considering the relevance of this gene in controlling cancer invasion and metastasis, approaches have been developed to uniquely and selectively target this gene. We also provide recent updates on strategies that have been successfully employed in targeting MDA-9/Syntenin resulting in profound pre-clinical anti-cancer activity.

A Subset of CXCR5+CD8+ T Cells in the Germinal Centers From Human Tonsils and Lymph Nodes Help B Cells Produce Immunoglobulins

Recent studies indicated that CXCR5⁺CD8⁺ T cells in lymph nodes could eradicate virus-infected target cells. However, in the current study we found that a subset of CXCR5⁺CD8⁺ T cells in the germinal centers from human tonsils or lymph nodes are predominately memory cells that express CD45RO and CD27. The involvement of CXCR5⁺CD8⁺ T cells in humoral immune responses is suggested by their localization in B cell follicles and by the concomitant expression of costimulatory molecules, including CD40L and ICOS after activation. In addition, CXCR5⁺CD8⁺ memory T cells produced significantly higher levels of IL-21, IFN-γ, and IL-4 at mRNA and protein levels compared to CXCR5⁻CD8⁺ memory T cells, but IL-21-expressing CXCR5⁺CD8⁺ T cells did not express Granzyme B and perforin. When cocultured with sorted B cells, sorted CXCR5⁺CD8⁺ T cells promoted the production of antibodies compared to sorted CXCR5⁻CD8⁺ T cells. However, fixed CD8⁺ T cells failed to help B cells and the neutralyzing antibodies against IL-21 or CD40L inhibited the promoting effects of sorted CXCR5⁺CD8⁺ T cells on B cells for the production of antibodies. Finally, we found that in the germinal centers of lymph nodes from HIV-infected patients contained more CXCR5⁺CD8⁺ T cells compared to normal lymph nodes. Due to their versatile functional capacities, CXCR5⁺CD8⁺ T cells are promising candidate cells for immune therapies, particularly when CD4⁺ T cell help are limited.

The enhancing effect of Klebsiella pneumoniae lysate on cellular immunity

Cellular immunity plays important roles in clearing intracellular pathogens or tumor cells. It is of significance to develop an adjuvant able to efficaciously induce cellular immunity, but such an approved adjuvant is not currently available. Klebsiella pneumoniae ( K. pneumoniae) possesses lipopolysaccharide and capsular polysaccharide, both of which have been demonstrated to be able to induce humoral immunity. In this study, we investigated the effect of K. pneumoniae on epidermal cellular immunity, in vitro. The effects of K. pneumoniae on the maturation of Langerhans cells (LCs), the capacity to induce T-cell proliferation, and the secretion of interferon gamma (IFN-γ) by T cells were examined. The results showed that K. pneumoniae induced significant upregulation of CD86 and human leukocyte antigen-deterodimer (HLA-DR) levels on LCs, but not CD40 and CD80. K. pneumoniae-loaded LCs induced significant CD4+ and CD8+ T-cell proliferation. Significant increases in extracellular IFN-γ secretion by CD4+ and CD8+ T cells stimulated with K. pneumoniae-pulsed LCs using enzyme-linked immunospot assay (ELISPOT) were demonstrated, while only a part of the subjects showed increases in intracellular secretion of IFN-γ using intracellular staining assay. In sum, K. pneumoniae has the potential to enhance epidermal cellular immunity and may act as a potential adjuvant in intradermal vaccines designed to enhance cellular immunity.

Conventional CD4+ T cells present bacterial antigens to induce cytotoxic and memory CD8+ T cell responses

Bacterial phagocytosis and antigen cross-presentation to activate CD8⁺ T cells are principal functions of professional antigen presenting cells. However, conventional CD4⁺ T cells also capture and kill bacteria from infected dendritic cells in a process termed transphagocytosis (also known as transinfection). Here, we show that transphagocytic T cells present bacterial antigens to naive CD8⁺ T cells, which proliferate and become cytotoxic in response. CD4⁺ T-cell-mediated antigen presentation also occurs in vivo in the course of infection, and induces the generation of central memory CD8⁺ T cells with low PD-1 expression. Moreover, transphagocytic CD4⁺ T cells induce protective anti-tumour immune responses by priming CD8⁺ T cells, highlighting the potential of CD4⁺ T cells as a tool for cancer immunotherapy.

Antigen presentation is generally considered the domain of innate immune cells, but CD4⁺ T cells can transphagocytose bacteria from infected dendritic cells. Here the authors show CD4⁺ T cells can transphagocytose bacterial and tumour antigens and present them to CD8⁺ T cells to activate memory and cytotoxic functions.