A sensitive isotope modification of the mixed haemadsorption test applicable to the study of prozone effects.

Investigations of surface antigens of animal cells require sensitive and quantitative methods. A modification of the mixed haemadsorption technique (MHT) suitable for such purposes is presented. The indicator cells have been labelled with chromium-51. During studies of experimental conditions, including reproducibility and sensitivity, the technique was used in four model systems including histocompatibility (H-2, HL-A), species, organ and blood group antigens. Isotope labelling of the indicator cells has rendered the test more sensitive and in addition some qualitative properties of antigen—antibody interaction have been studied. The test procedure is simple and fast.