Research Techniques Made Simple: Monitoring of T-Cell Subsets using the ELISPOT Assay

The enzyme-linked immunospot (ELISPOT) assay allows characterization of single-cell immune responses through detection of secreted analytes. Although ELISPOT analysis shares similarities with ELISA, it has some essential differences. In general, the ELISPOT assay uses antibodies to capture and detect analytes of interest released by activated immune cells. Released analytes form specific antibody-antigen complexes and are visualized as spots of enzyme-substrate precipitates. These spots indicate both how many cells secrete the respective analyte and how much analyte is produced per individual cell. Initially developed for the detection of antibody-secreting cells, ELISPOT assays are now frequently performed both in the context of clinical diagnostics and in research on T-cell responses, in particular antigen-specific T-cell subpopulations, as related to allergy, cancer, infections, or autoimmune diseases. The one spot-one cell principle allows sensitive detection of specific and rare immune cell subsets. Here we present general principles, applications, and recent modifications of the ELISPOT technique.