Elispot Technique for Assaying Interleukins

The enzyme-linked immunosorbent assay (ELISA) spot (ELISPOT) procedure is basically a modification of the plaque techniques, hence its initial synonym ELISA plaque assay. Plaque assays allow the enumeration of antibody-secreting cells by diluting them in an environment in which the antibody formed by each individual cell produces a readily observable effect. Based on this principle, Czerkinsky and coworkers (1 ) first described a modification of this technique which could be used for the detection and enumeration of antibody-producing cells in vitro. In this modified assay, a suspension of single antibody-forming cells was incubated on a precoated solid phase, i.e., on a dish of immobilized antigen, to which specific antibody secreted during the incubation period would bind. This locally captured antibody was visualized after removal of the cells by treatment with an enzymeconjugated anti-immunoglobulin and development of a color reaction by incorporating the substrate in a gel that was poured over the ground of the dish. Limited diffusion of the colored reaction product in the gel provided a series of macroscopic spots that were readily enumerated.