Power analysis: Using the Pearson Chi-square test for two proportions, with the assumption that 75% of all OFC+ to tree-nuts will be positive to at least one specific component, in order to detect a result with a P-value of <0.05, 15 positive and 15 negative sera for each tree-nut would yield a power of 0.816. Based on the investigators experience with immunoreactivity as assessed by western blot, in fact the investigators would expect that much more than 75% of OFC+ patients would show IgE reactivity against at least one component. Thus, the investigators feel that a total of thirty sera for each tree-nut should suffice for the analysis.