Experimental pulpal immunization. I. Route of application and demonstration of immune response.

The experimental exposure of the pulpal room of rabbit teeth made it possible to apply an ovalbumin agar gel deposit into the pulpal room and subsequently investigate the immune response. Diffusion of antigen from the agar into environment was proven. After 3 weekly applications 5 rabbits showed hemagglutinating anti-ovalbumin titers between 1:128 and 1:512, while 7 rabbits receiving 10 weekly applications had titers between 1:8000 and 1:128,000. Control rabbits which received the agar deposit alone showed no antibody response. Control rabbits which obtained 3 identical weekly doses of ovalbumin in PBS by subcutaneous injection showed an identical immune response as animals immunized via the pulpal room. Specificity of antibodies was ascertained by passive hemagglutination with control antigens and hemagglutination inhibition. Intradermal injection of ovalbumin in 3 rabbits which obtained pulpal immunization, induced an Arthus reaction. The precipitating property of ovalbumin antibodies and their identity with defined ovalbumin antisera was proven by gel diffusion. The results obtained show, that antigens present in the pulpal room provide a strong immunogenic stimulus.