Three fractions of rye-grass (Lolium perenne) pollen extract have been isolated by preparative isoelectric focusing (i.e.f.) and characterized in terms of physicochemical and immunochemical properties. The purified components were designated 'R7' and 'R14' on the basis of their positions in relation to other rye-grass pollen extract components on SDS/polyacrylamide-gel electrophoresis and their apparent molecular masses were assessed as 31 and 11 kDa respectively. On i.e.f., R14 split into two components, one acidic (pl 5.0) and one basic (pl 9.0), termed 'Rl4a' and 'Rl4b' respectively, and R7 focused at pl 5.8. R7 and R14a were shown to be allergenic by skin-prick test and all three components were recognized by rye-grass-pollen-specific human IgE. On SDS/polyacrylamide-gel electrophoresis and i.e.f., R7 behaved in a manner identical with that shown by an authentic sample of Rye I and gave an amino acid analysis similar to published data Immunochemistry 3, 91-100] for Rye group-I isoallergens; the amino acid sequence of the first 27 N-terminal amino acids was also determined. Physicochemical analysis revealed that R14a was equivalent to Rye II and 14b to Rye III. Preparative i.e.f. followed by gel-permeation chromatography proved to be a rapid and efficient method for purifying the allergenic components of Rye I (R7), Rye II (Rl4a) and Rye III (Rl4b) from rye-grass pollen extract.

Rye grass pollen extract was fragmented by sequential treatments with cyanogen bromide and 2-nitro-5-thiocyanobenzoic acid, and a fraction containing fragments of molecular weight greater than 10,000 M_r was isolated. The in vitro reactivity of the extract with specific IgE was extensively reduced by fragmentation. Less reduction in activity was shown either by skin testing or by inhibition of an extract-specific IgG-binding assay. Reactivity with, and ability to induce, extract-specific mouse T cells were retained by the fragment preparation, and the ability to cause transformation of lymphocytes from atopic donors was unchanged. Fragments did not induce extract-specific IgG antibody in mice, were unable to stimulate the production of T-helper cells which could collaborate in an adoptive cell-transfer system, and did not induce delayed hypersensitivity reactions in guinea pigs. The possibility that such T-cell-reactive modified allergens (T’allergoids) might be used to stimulate selectively T-cell subsets and, therefore, could be used to advantage in immunotherapy is discussed.

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A procedure utilising the latent activating potential of the 4-(methylmercapto)phenyl ester group has been developed for the controlled, reproducible preparation of macromolecular conjugates. This ester, as part of a succinyl-bridging group, was used to couple the water-soluble, amino acid polymer, poly-(N-methylglycine) (polysarcosine), via its N-terminal secondary amine, with the nucleophilic components of the aqueous extract of a mixture of grass pollens. The products exhibit a reproducible, antigen-specific suppressive effect on the in vivo synthesis of IgE in mice.

The ability of lymphocytes obtained from mice treated with whole rye grass pollen extract or purified major allergen components (R7 – apparent molecular weight 31,000; R14a – apparent molecular weight 11,000) to proliferate in culture on challenge with these allergens has been studied. Whole rye grass pollen extract was found to stimulate responses with lymphocytes from all treated but not non-treated animals, whereas the purified allergens failed to effect proliferation except with cells obtained from animals treated with the homologous allergen. These results accord with previous observations that, of the antigen present in the whole rye grass pollen extract, the components showing greatest immunogenicity in murine systems are not those commonly regarded as being the major allergens in man. The mouse may not thus provide a relevant model of human immune responses to rye grass pollen extracts.