Quantitation of helper factor activity. I. Utilization of the ELISA method to measure helper activity in the secondary antibody response

We describe here a simple culture system for measuring the effects of regulatory cells or factors on the secondary antibody response which uses the enzyme-linked immunosorbent assay (ELISA) to detect antibody production. This technique offers several advantages over methods which measure hemolytic plaque-forming cells. Helper factors purified from the supernatant of in vitro primed helper cells were shown to specifically enhance antibody production from primed spleen cells by from 2- to 4-fold in this system.