Microwave stimulation of an immunological reaction (CEA/anti-CEA) and its use in immunohistochemistry

The effects of microwave stimulation on different aspects of immunohistochemical reactions were studied using Elisa as a model system. This technique allows monitoring of (i) the rates and recoveries of different antigen-antibody reactions, (ii) the formation of avidin/biotin complexes, (iii) the prevention of non-specific activity and (iv) the washing procedures. The binding reactions seemed to follow second-order kinetics, and reaction rates were considerably enhanced by microwave stimulation. The steps were aimed at preventing non-specific reactivity and the washing procedures could all be shortened to seconds. Such rate increases are far too large to be explained solely by the modest increase in temperature. Furthermore, microwave irradiation caused a major reduction in the yield of antigen-antibody complexes. This inhibitory effect can be compensated for by increasing the concentration of antibody. No significant effects of the microwaves on the antigen-antibody complexes were found once the complexes had been formed. The obtained results were then applied to the demonstration of carcinoembryonic antigen in histological material. By employing this method a complete immunohistochemical staining of a hydrated tissue section could be performed within 15 min, excluding the final development of colours.