RESUMEN
CD4+ T cells are central to adaptive immunity. Their role in cross-protection in viral infections such as influenza and severe acute respiratory syndrome (SARS) is well documented; however, molecular rules governing T cell receptor (TCR) engagement of peptide-human leukocyte antigen (pHLA) class II are less understood. Here, we exploit an aspect of HLA class II presentation, the peptide-flanking residues (PFRs), to "tune" CD4+ T cell responses within an in vivo model system of influenza. Using a recombinant virus containing targeted substitutions at immunodominant HLA-DR1 epitopes, we demonstrate limited weight loss and improved clinical scores after heterosubtypic re-challenge. We observe enhanced protection linked to lung-derived influenza-specific CD4+ and CD8+ T cells prior to re-infection. Structural analysis of the ternary TCR:pHLA complex identifies that flanking amino acids influence side chains in the core 9-mer peptide, increasing TCR affinity. Augmentation of CD4+ T cell immunity is achievable with a single mutation, representing a strategy to enhance adaptive immunity that is decoupled from vaccine modality.
Asunto(s)
Linfocitos T CD4-Positivos , Virus de la Influenza A , Mutación , Receptores de Antígenos de Linfocitos T , Animales , Femenino , Humanos , Ratones , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Epítopos/inmunología , Virus de la Influenza A/inmunología , Virus de la Influenza A/genética , Gripe Humana/inmunología , Gripe Humana/virología , Gripe Humana/prevención & control , Activación de Linfocitos/inmunología , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/virología , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Receptores de Antígenos de Linfocitos T/genéticaRESUMEN
PURPOSE: Broadly expressed, highly differentiated tumor-associated antigens (TAA) can elicit antitumor immunity. However, vaccines targeting TAAs have demonstrated disappointing clinical results, reflecting poor antigen selection and/or immunosuppressive mechanisms. EXPERIMENTAL DESIGN: Here, a panel of widely expressed, novel colorectal TAAs were identified by performing RNA sequencing of highly purified colorectal tumor cells in comparison with patient-matched colonic epithelial cells; tumor cell purification was essential to reveal these genes. Candidate TAA protein expression was confirmed by IHC, and preexisting T-cell immunogenicity toward these antigens tested. RESULTS: The most promising candidate for further development is DNAJB7 [DnaJ heat shock protein family (Hsp40) member B7], identified here as a novel cancer-testis antigen. It is expressed in many tumors and is strongly immunogenic in patients with cancers originating from a variety of sites. DNAJB7-specific T cells were capable of killing colorectal tumor lines in vitro, and the IFNγ+ response was markedly magnified by control of immunosuppression with cyclophosphamide in patients with cancer. CONCLUSIONS: This study highlights how prior methods that sequence whole tumor fractions (i.e., inclusive of alive/dead stromal cells) for antigen identification may have limitations. Through tumor cell purification and sequencing, novel candidate TAAs have been identified for future immunotherapeutic targeting.