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Updated: Dec 17, 2025
In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model
Published on: November 28, 2017
In vitro platform establishes antigen-specific CD8+ T cell cytotoxicity to encapsulated cells via indirect antigen
Ying Li1, Anthony W Frei2, Ethan Y Yang3
1J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; Graduate Program in Biomedical Sciences, College of Medicine, University of Florida, Gainesville, FL, USA.
The curative potential of non-autologous cellular therapy is hindered by the requirement of anti-rejection therapy. Cellular encapsulation within nondegradable biomaterials has the potential to inhibit immune rejection, but the efficacy of this approach in robust preclinical and clinical models remains poor. While the responses of innate immune cells to the encapsulating material have been characterized, little attention has been paid to the contributions of adaptive immunity in encapsulated graft destabilization. Avoiding the limitations of animal models, we established an efficient, antigen-specific in vitro platform capable of delineating direct and indirect host T cell recognition to microencapsulated cellular grafts and evaluated their consequential impacts. Using ovalbumin (OVA) as a model antigen, we determined that alginate microencapsulation abrogates direct CD8+ T cell activation by interrupting donor-host interaction; however, indirect T cell activation, mediated by host antigen presenting cells (APCs) primed with shed donor antigens, still occurs. These activated T cells imparted cytotoxicity on the encapsulated cells, likely via diffusion of cytotoxic solutes. Overall, this platform delivers unique mechanistic insight into the impacts of hydrogel encapsulation on host adaptive immune responses, comprehensively addressing a long-standing hypothesis of the field. Furthermore, it provides an efficient benchtop screening tool for the investigation of new encapsulation methods and/or synergistic immunomodulatory agents.
The curative potential of non-autologous cellular therapy is hindered by the requirement of anti-rejection therapy. Cellular encapsulation within nondegradable biomaterials has the potential to inhibit immune rejection, but the efficacy of this approach in robust preclinical and clinical models remains poor. While the responses of innate immune cells to the encapsulating material have been characterized, little attention has been paid to the contributions of adaptive immunity in encapsulated graft destabilization. Avoiding the limitations of animal models, we established an efficient, antigen-specific in vitro platform capable of delineating direct and indirect host T cell recognition to microencapsulated cellular grafts and evaluated their consequential impacts. Using ovalbumin (OVA) as a model antigen, we determined that alginate microencapsulation abrogates direct CD8+ T cell activation by interrupting donor-host interaction; however, indirect T cell activation, mediated by host antigen presenting cells (APCs) primed with shed donor antigens, still occurs. These activated T cells imparted cytotoxicity on the encapsulated cells, likely via diffusion of cytotoxic solutes. Overall, this platform delivers unique mechanistic insight into the impacts of hydrogel encapsulation on host adaptive immune responses, comprehensively addressing a long-standing hypothesis of the field. Furthermore, it provides an efficient benchtop screening tool for the investigation of new encapsulation methods and/or synergistic immunomodulatory agents.
