As the precipitating antibodies in rabbits to house dust were considered to correspond to the blocking antibodies produced by hyposensitization treatment, rabbit anti-house dust antibody was used to investigate the antigenicity of house dust producing blocking antibody in human. The summary of the obtained results were as follows:
1) By the use of rabbit anti-house dust serum it was found that house dust extract contained at least three antigenic elements and the specific activity of the antibodies to house dust was displayed by the 7S gammaglobulin and not by the 19S macroglobulin fraction in radioimmunodiffusion test.
2) Fractionation of the house dust extract by gel diffusion and radioimmunoelectrophoresis disclosed that the protein fraction contained two antigenic components. Furthermore, one of these components was deprived of its antigenecity by the action of pronase but no antigenicity was demonstrated in polysaccharide fraction. On the other hand, Morris and his co-workers were unable to detect significant loss in skin reactivity to purified house dust fraction submitted to treatment with pronase.
3) Using mite extract and candida extract, cross reactions to anti-house dust serum were investigated with gel diffusion, but reactions were negative for both while Miyamoto et al. reported a close correlation between extract of house dust and considered mites as the main allergen in house dust.
4) From these results, the allergenicity of house dust in skin test and the antigenicity of house dust to blocking antibodies in man might be dissociated in some instances.
