[Enzymo-immunological estimations. Principles and applications (author's transl)].

Diagrams of the reactions of enzymo-immunological estimations are similar to those of radio-immunoassay. The only difference is that an enzymatic label is substituted on the antigen or the antibody for the isotopic label and that consequently a measurement of enzyme activity replaces isotopic counting. One must therefore add a further stage of substrate addition and a stage of enzyme reaction. There is however a technic which has no equivalent in radio-immunoassay, the EMIT system, where one measures the change in activity of a haptenised enzyme under the influence of the corresponding anti-haptene antibody. The author reviews the main problems raised by the first group of technics and gives a few examples of the results of estimation of alpha-foeto-protein obtained with 3 different reactions with fairly similar performances. The advantages and disadvantages of enzymo-immunologic technics are reviewed. The two major advantages seem to be the stability of the reagents and the fact that they avoid the administrative controls which restrict the use of isotopes.