1. 1. A minimum of 6 bands of precipitation were detected in Alternaria extracts by the gel diffusion method. 2. 2. Alternaria antigens differ in their relative heat and pH stability. Two of them were found to be very resistant and to retain their precipitating properties after exposure to extremes of pH and to autoclave temperatures during one hour. 3. 3. Thermostable components were found to produce positive skin tests in Alternaria-sensitive patients, although a drop in titer was observed in some individuals when compared with the unheated extract. 4. 4. Trypsin, diastase, and pepsin did not exert any detectable digestive action upon the antigens of Alternaria. 5. 5. Agar immunoelectrophoresis dissociated the Alternaria antigens into 4 precipitin arcs migrating toward the anode, one prominent arc migrating toward the cathode, but partially extending into the anode, and an arc, apparently remaining near the origin. The last two arcs were thermostable. 6. 6. The peak of greatest skin reactivity coincides with the location of the prominent thermostable arc of precipitation and also with a zone of maximum carbohydrate and polypeptide staining. 7. 7. Tannic acid hemagglutination and simple indirect hemagglutination tests were successful only after heating the Alternaria extracts. Unheated extracts failed to coat the cells with antigen. The hemagglutination titer increased with an increase in the degree of heating of the extracts. 8. 8. Heating did not impair the antigenicity of Alternaria extract in rabbits or alter the specificity of the heat stable antigens. 9. 9. Alternaria-sensitive patients showed an increase in titer after hyposensitization treatment over their pre-treatment levels by the indirect hemagglutination test using cells sensitized with heated antigen. A low level of antibody was detectable in some of the normal individuals. 10. 10. Alternaria was found to have antigens in common with most of the other members of the Dematiaceous group, as well as specific antigens not shared with the others. 11. 11. Antigens chemically extracted from Alternaria by the "phenol" and "formamide" procedures gave precipitin bands of identity with the thermostable antigens. 12. 12. Both the phenol and the formamide extracted substances were skin active in Alternaria-sensitive patients, but the phenol extracted material seemed more potent.
ASJC Scopus subject areas