Antigenic activity in monkey and human of purified low molecular weight fractions of Timothy pollen.

Small molecular weight fractions obtained from dialysis of crude Timothy pollen extract were shown to carry immunogenic activity in monkeys. Three fractions were sequentially purified through gel filtration with Siphadex G-10 and C-M cellulose 52. Monkeys immunized with these fractions produced almost exclusively skin-sensitizing antibodies which were shown to be of the IgE class and differing in antigenic specificity. The analysis of sugars and amino acids contained in two of these fractions showed large qualitative and quantitative differences. It is assumed that these fractions might represent oligomeric subunits of larger antigenic molecules. Challenge of patients allergic to Timothy pollen by means of skin tests and nasal provocation tests further confirms the absence of cross-antigenicity among the 3 active fractions. These results seem to indicate heterogenicity of IgE antibodies as developed following sensitization with crude Timothy pollen antigen.