ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) - MEASURE OF ANTIBODY CONCENTRATION OR AFFINITY

The immune response of rats to 2,4-dinitrophenyl (DNP) following both primary and secondary immunization with DNP-BGG has been studied using five techniques for the quantitative measurement of antibody: the standard ELISA, amplified ELISA, Farr assay, precipitation and a double-antibody precipitin assay. In addition, antibody affinity was measured by a modification of the Farr assay. Results are consistent with the view that while the Farr assay is a good indicator of total antibody. as measured by double-antibody precipitation, both ELISA assays correlate better with changes in antibody affinity. The amplified ELISA is comparatively less correlated with antibody affinity than the standard ELISA and only the amplified ELISA is capable of detecting the low affinity antibody detectable by double-antibody precipitation and by the Farr assay. Because of the influence of affinity on measurements made by the ELISA. results are best expressed as ELISA units rather than μg antihody/ml. © 1978.