Reduced allergenicity of high molecular weight ragweed polymers.

Polymerized ragweed antigens of different molecular weight ranges were studied to determine if the degree of allergenicity was dependent on molecular size of the polymers. In this study, allergenicity is defined as the ability to elict IgE-mediated skin reactivity. Ragweed antigen treated with glutaraldehyde was fractionated into one preparation with a molecular weight range of 200,000 to 20,000,000 and another with molecular weights less than 200,000. Except for the difference in molecular sizes of the two molecular sizes of the two preparations, all ragweed polymers had been treated in an identical fashion. The low molecular weight fraction had cutaneous endpoint reactivity greater than 10(5) to 10(8) times that of the high molecular weight materials. In these and other studies, immunogenicity defined as the ability to induce an IgG antibody response was retained by the high molecular weight material. The results are consitent with the hypothesis that allergenicity decreases as the molecular weight of the polymerized allergen increases.