panallergens (lipid transfer proteins, profilins, Bet v1-related proteins) and evolutionarily conserved proteins (seed storage proteins) occur in various tree nuts (Roux et al., 2003).
I. Published Challenge Studies An extensive literature review was conducted from November 2004 through April 2005 that included key word, author, and “related article” searches of the PubMed database and analysis of citations found in the published literature. Seventeen publications with quantitative dose-response data from DBPCFC testing were reviewed to identify those that contained data that could be used to estimate LOAEL levels for the major food allergens. These studies are described in more detail in Appendix 2. Fourteen (82%) of these report results from testing adults; the remaining three tested infants and children. In four cases, the population being studied was not specifically chosen to be food allergic, and a large fraction of the individuals in these populations did not respond to the highest doses tested. In eight studies (47%), patients reacted to the lowest dose tested, and in three studies there was insufficient information to determine either the lowest dose used or the number of patients who responded to that dose. The most sensitive population was seen by Hourihane et al. (1997b), who reported that 67% of the patients tested reacted to “peanut rubbed on the lip,” including one severe reaction.
Peanut. Hourihane et al. (1997b) observed the lowest measured dose of an allergen that provoked a reaction (i.e., a LOAEL), 0.1 mg of peanut protein provoked subjective reactions in two patients and 2 mg of peanut protein provoked an objective reaction in one patient. Objective reactions were observed in two other patients on exposure to 5 mg of peanut protein. Wensing et al. (2002a) also reported a LOAEL of 0.1mg for subjective reactions in two of 26 peanut allergic individuals tested. The LOAEL for the intial objective symtom was 10 mg. Several other papers reported LOAELs of 25-100 mg of peanut protein for objective reactions (May, 1976; Hourihane et al., 1997a; Bock et al., 1978).
Egg. A wide range of LOAELs have been observed for egg. Caffarelli et al. (1995) reported a LOAEL of 0.5 mg of dried whole egg (approximately 0.42 mg protein). Bock et al. (1978) reported observing an objective reaction with 25 mg of whole egg (approximately 1 mg protein), although the data are difficult to interpret as presented. In contrast, Eggesbo et al. (2001) report a LOAEL of 1 g of whole egg (approximately 260 mg of protein) for an objective reaction.
Milk. Relatively consistent LOAELs have been reported for milk. Bellioni-Businco et al. (1999) found a LOAEL of 1 ml of whole milk (approximately 362 mg of protein) with children, and Pastorello et al. (1989) found a LOAEL of 0.5 g of freeze-dried milk (approximately 187 mg of protein) with adults.
Soy. LOAELs of approximately 522 and 88 mg protein have been reported for soy (Zeiger et al., 1999; Magnolfi et al., 1996).
Tree Nut. Hazel nut is the most commonly studied tree nut. Wensing et al. (2002b) observed reactions to 1 mg of hazel nut protein in 4 of 29 patients, which was the lowest
Revised Threshold Report Page 31 of 108