We wish to continue immunochemical studies of pollen allergens causing hay fever and asthma in allergic man. The allergens to be studied include those of rye grass Groups I, II and III, and certain as yet uncharacterized rapidly released components of ragweed, which are believed to be of great importance in ragweed pollen allergy. All allergens will be isolated in ultra-pure state. We will place particular emphasis on investigating the allergenic and antigenic determinants of ragweed allergen Ra5 which has a relatively simple structure (mol. wt. 5000). We will also vigorously pursue the development of allergen derivatives known as "allergoids," defined as derivatives which have greatly reduced allergenic activity, but which have largely retained the ability to immunize protectively against the native allergen. Such preparations have great potential usefulness in improving the immunotherapy of allergic humans. BIBLIOGRAPHIC REFERENCES: Marsh, D.G. Allergens and the genetics of allergy. In "The Antigens," Vol. III. (Ed.: M. Sela). Academic Press, New York, 1975, pp. 271-359. Roebber, M., Marsh, D.G. and Goodfriend, L. An improved procedure for isolation of ragweed pollen allergen Ra5. J. Immunol. 115: 303-304, 1975.