October 29, 2020
Key takeaways from this webinar:
Efficacy in a vaccine trial is assessed through the production of protective antibodies against the infectious agent. Measurement of the neutralizing effect of these antibodies is performed through cell-based assays. Over the past years, additional assays have been introduced in vaccine trials in order to get a better understanding of the vaccine’s mode of action on the immune system. These assays allow for the monitoring of T-cell responses in subjects upon vaccination, including the humoral response (supported by CD4 helper T cells) and the elimination of infected cells by CD8 cytotoxic T cells (cellular response). The mechanism can be further characterized through the profiling of the CD4 T cell polarization: Th1, Th2, Th17 and/or follicular helper T cells (Tfh), all of which can have an impact on the resulting therapeutic effect.
Flow cytometry and multimer detection can be used to follow an antigen specific T-cell response and reveal a specific TCR. However, this method allows to follow only one antigen and the functional state (effector/anergic) of the cells remains unknown. Given these limitations, most trials now employ ELISpot and ICS to reveal both the antigen-specificity and the functionality of the immune response induced by the treatment.
Performing both ELISpot and ICS assays requires a lot of starting material (PBMC isolated from whole blood), which might not be accessible. The question then arises: which method to use? ELISpot or ICS?On one hand, the ELISpot is commonly considered more sensitive than the ICS assay while requiring less amount of PBMC. On the other hand, the ICS allows for the measurement of cytokines as well as surface and intracellular markers to generate a more complete cellular profile but consumes more of the precious PBMC material.
During this webinar, we will present (a) characteristics of both methods as well as their advantages and limitations, (b) approaches to define optimal assay conditions during development for robust assay performance and maximal data gathering, (c) validation approaches based on intended use of the data, and (d) how to deploy these assays using appropriate criteria for control and study samples during sample analysis in infectious diseases (i.e., COVID-19) and immuno-oncology vaccine trials.
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