Retained T-cell reactivity of rye grass pollen extract following cleavage with cyanogen bromide and nitrothiocyanobenzoic acid.

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 Mr 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.