Whole Protein Immunogenicity Testing
EpiScreen™ Time Course T Cell Assays
A typical study uses PBMCs from a minimum of 50 donors which are carefully selected to provide a distribution of HLA-DR allotypes which represents the human population relevant to the study. Whole proteins are added to bulk cultures of pre-processed PBMCs, and T cell activation assay measurements are performed between days 5 and 8 post-stimulation. Proliferation and IL-2 secretion are two early markers of T cell activation and are measured using 3H TdR incorporation and EliSpot®, respectively. Strong correlation between these markers enables the detection of CD4+ effector T cell activation and discriminates between T cell effector and regulatory responses.
EpiScreen™ DC:T Cell Assays
For proteins which modulate T cell responses, the alternative EpiScreen™ “DC:T Cell” assay format is used whereby dendritic cells (DC) are separated from CD4+ T cells in the PBMCs prior to addition of the test sample. Immature DC are produced in vitro and are incubated with the test protein to enable protein uptake and intracellular processing of peptide T cell epitopes (‘antigen loading’). Excess protein is removed by washing and the DC are induced to a fully mature phenotype in vitro. Autologous CD4+ T cells are co-cultured with the mature ‘antigen loaded’ DC for 7 days prior to measuring T cell stimulation, typically by proliferation (3H TdR) and IL-2 secretion (EliSpot®).