The ELISA-plaque assay for the detection and enumeration of antibody-secreting cells. An overview.

A solid-phase immunoenzymatic technique has been developed which allows the ready detection and enumeration of total- and antigen-specific immunoglobulin-secreting cells (ISC). The procedure involves the addition of putative ISC to plastic wells pre-coated with specific antigen or antisera. During incubation, the product of a single cell is immobilized by the solid phase at the point of release providing an immunological 'finger print' of the ISC which is subsequently developed by the application of appropriate enzyme-anti-Ig conjugates and an enzyme substrate which yields an insoluble product after incubation. Blue spots or 'ELISA plaques' are thus produced and can be counted macroscopically. This technique has been employed in rat, mouse and human systems and in each case appears to be of equivalent or greater sensitivity to existing haemolytic plaque techniques. The assay is particularly suited to the enumeration of antigen-specific ISC in which the antigen is difficult to couple to red cells or where a high degree of discriminating power is necessary as is required for example in the enumeration of IgE-ISC.