T-cell costimulatory receptors (CD28 and CD27) (CD28/CD27)

Alpha-type-1 polarized dendritic cells (αDC1) are a specialized subset of mature dendritic cells characterized by high expression of the costimulatory ligands CD80, CD86, and CD70, alongside robust production of IL-12p70 [3, 4, 6]. These ligands interact with their respective receptors on T cells—CD28 (for CD80/CD86) and CD27 (for CD70)—to provide the essential Signal 2 and Signal 3 required for optimal T-cell activation, proliferation, and survival [1, 7, 8]. In the context of cancer immunotherapy, αDC1-based vaccines and agonistic antibodies (e.g., targeting CD27) aim to exploit this axis to drive potent Type-1 (Th1/CTL) immune responses against tumors [5, 9, 10]. Conversely, in autoimmune diseases like rheumatoid arthritis, the CD80/CD86-CD28 interaction is targeted for blockade (e.g., by Abatacept) to suppress aberrant T-cell activity [1, 2]. The αDC1 phenotype is typically induced ex vivo using a specific maturation cocktail containing IFN-gamma and TLR agonists, making these cells a powerful tool for personalized cancer vaccines [3, 4]. By ensuring high-density presentation of costimulatory molecules, αDC1 cells can overcome the immunosuppressive environment of the tumor and effectively prime naive T cells [6, 9]. Clinical trials have explored αDC1 vaccines in various malignancies, including glioma and melanoma, often in combination with other immunomodulators [9]. The safety profile of targeting these pathways varies, with checkpoint inhibitors often associated with immune-related adverse events, while costimulatory agonists require careful dosing to avoid cytokine storms [1, 2].

Other names

CD28CD27B7-1/B7-2/CD70 receptorsCostimulatory pathwayαDC1 costimulatory axisT-cell costimulatory receptors

The mechanism of action involves the modulation of T-cell activation through the interaction of costimulatory receptors and their ligands. Drugs like Abatacept and Belatacept are CTLA-4-Ig fusion proteins that bind to CD80 and CD86 on antigen-presenting cells, preventing them from binding to CD28 on T cells and thereby inhibiting T-cell costimulation [1, 2]. Ipilimumab and Tremelimumab are checkpoint inhibitors that block CTLA-4, preventing it from outcompeting CD28 for CD80/CD86 binding, thus enhancing T-cell activation [1, 9]. Varlilumab is an agonistic antibody that targets CD27 to promote T-cell expansion and survival, while Cusatuzumab is an antagonistic antibody targeting CD70 to inhibit the growth of CD70-expressing malignant cells [10].