<qa>  What is the purpose of this study?The purpose of this study is to evaluate the residual allergenicity of the modified ragweed pollen in Ragweed MATA MPL modified pollen allergen tyrosine adsorbate Monophosphoryl Lipid A by skin prick testing. This is done by a comparison of the wheal response after skin prick testing with different concentrations of aqueous native allergen, modified allergen, modified tyrosine adsorbed allergen, and Ragweed MATA MPL. 