Type IV Delayed-type hypersensitivity (DTH) is a cell-mediated, antigen-specific immune reaction, generally predictive of T cell function and response. The Type IV DTH model is an important clinical tool that has been widely adopted and can be useful for allergy testing, determining immune resistance to pathogens, predicting vaccine immunogenicity, and more. This model typically includes a sensitization phase, where the animals will be administered a test article that will expose them to the antigen of interest. The animals will then be subject to a challenge with the same antigen by an intradermal ear injection. The T cell activation and resulting inflammation can be assessed with physical measurements of the localized swelling and downstream blood and tissue analyses as outlined below.

• Advantages: rapid in vivo assay, clinically translational model, predictive of cell-mediated immune responses.
• Disadvantages: less adaptive to high-throughput screening than in vitro assays.

• C57Bl/6 Mice or similar

• Percent weight change
• Ear thickness change

• Cytokine/chemokine multiplex analysis
• Immunophenotyping
• Serum ELISAs for Ab detection
• Terminal histopathology and/or IHC analyses
• Custom assays