Abstract
While the photodynamic action of dyes was well known 30 years ago, its application to microbiology was limited to the studies on their lethal action on bacteria and protozoa, and the inactivating action on toxin, antibodies, and complement. 1 It was only in the last few years that the immunological activities of the treated substances were carefully examined. Perdrau and Todd 2 reported on the preservation of antigenicity of canine distemper virus inactivated by photodynamic action of methylene blue. Others have since studied the antigenic action of various photodynamically inactivated bacteria 3 and viruses 4 as well as toxins, 5 and in the majority of instances this has been well preserved. Furthermore, it has been suggested 3 that organisms so treated may actually make better vaccine than those treated with heat or formalin. However, the reason for this better antigenicity is not clear. It might be conceived that the less change is made in the chemical structure of the antigen, the more complete is its antigenicity. It would be difficult, however, to study chemically the change produced by photosensitization on bacteria or viruses, but it is relatively simple to study the change produced on antibodies, particularly with those in a relatively pure state. In such a case, the immunological activity will then act as an index of the photodynamic action. The result of such a study is herewith presented.
The general technic of photosensitization used in this study is essentially the same as that previously reported 3 with the exception that the immune serum was always diluted 40-100 times before exposure. Both methylene blue and eosin were employed and their effect on the immune activity of various antibodies was observed. Furthermore, the action of eosin in the presence of light on the chemical properties of a purified antipneumococcus horse precipitin 6 was also examined.
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