A stable chemiluminescent-labelled antibody for immunological assays

RADIOISOTOPES, in particular 125I, have been used for many years as labels for monitoring the distribution of reagents in immunological assay systems. Satisfactory labelled derivatives are not always easily produced as iodination frequently produces severe molecular disruption. Moreover, iodinated proteins have a limited shelf life and sometimes require extended counting times for accurate quantitation. Recently, non-radioactive labels such as bacteriophages1,2, enzymes3,4, stable free radicals5 and fluorescent groups6 have been used in attempts to overcome some of these problems. We describe here the successful labelling of antibodies to rabbit IgG with a chemiluminescent molecule and the development of an immunological assay using chemiluminescence as a means of monitoring reagent distribution.