3. Paulsen E, Stahl S, Bindslev-Jensen C, Voitenko V, Poulsen LK. Occupational type I allergy to Christmas cactus (Schulumbergera). Allergy 1997;52: 656–660. 4. Andersen F, Bindslev-Jensen C, Stahl S, Paulsen E. Immediate allergic and nonallergic reactions to Christmas and Easter cacti. Allergy 1999;54:511–516. 5. Damiani E, Aloia AM, Priore MG, Delle Donne P, Nettis E, Ferrannini A. Allergy to red pitaya. Allergy 2008;63:1252–1253. 6. Towbin N, Staehelin T, Gordon J. Electrophoretic transfer of proteins from polyacrylamide gel to nitrocellulose sheets. Procedure and applications. Proc Natl Acad Sci USA 1979;76:4350– 4354. Human milk fortifier in preterm babies: source of cowÕs milk protein sensitization? V. Vlieghe, A. D. Roches, A. Payot, C. Lachance, A. M. Nuyt * Key words: cow's milk allergy; human milk fortifier; human milk supplements; premature infants. We report the cases of three preterm infants who presented signs suggestive of sensitization to cowÕs milk protein after supplementation of their motherÕs milk with a human milk fortifier (Table 1). CowÕs milk protein allergy (CMA) affects 2–7% of the pediatric population and the incidence is increasing. Symp- toms usually appear during the first months of life and occasionally in the neonatal period for term and preterm infants (1–3). When preterm babies are fed human milk (HM), it is recommended to add commercially available fortifiers to meet all specific nutritional needs. In North America, these fortifiers are generally produced from cowÕs milk nonhydrolyzed proteins. The relationship between the use of a human milk fortifier and the symptoms evocating cowÕs milk protein sensitization has not, to our knowledge, been previously reported despite its extensive use in neonatal units. The product contains: ÔNonfat milk, corn syrup solids, whey protein concentrate, and MCT oil (fractionated coconut or palm kernel oil)Õ as sources of proteins, fat, and carbohydrate (Abbott Laboratories Pediatric Nutritional Products Guide, DIR/98A08, 2008, Mississauga, Canada). The corn syrup solids are the sole source of carbohydrates and do not contain proteins (id). Casein represents 80% of milk protein and is the major allergen in CMA. In the neonatal period, cases of CMA are increasingly recognized including in premature infants (1, 2). Precocious exposure to cowÕs milk proteins increases the risk of developing CMA (4). The immature intestine has an increased permeability, especially in preterm babies, as integrity of the intestinal epithelium is affected by multiple factors (feeding restrictions, ischemic injuries, and high production of free radicals). One can therefore postulate that premature infants are at increased risk of exposure to food allergens and development of food allergy (such as CMA). The oral challenge to diagnose CMA carries risk of significant allergic reac- tions which prohibits its systematic use in newborns and even more so in premature infants. Therefore, the diagnosis of CMA in the neonatal period is essentially based on the clin- ical response to the elimination of the allergen from the diet. The eosinophil count is not currently considered to be a significant adjunct to diagnosis of food allergies in young children, although a relationship between in- creased serum concentrations of IL-5 and marked eosinophilia in an infant with CMA has been reported (5). Transient eosinophilia can be present in prematurely born infants during the first month of life, has been associated with inflammation states [infection, necrotizing enterocolitis (NEC)] and transfusions, and is often considered nonspecific (6). In the presented cases, eosinophilia correlated with the clinical symptoms; whether eosinophilia could be an adjunct for the diagnosis of CMA in premature infants remains to be demonstrated. Even though CMA is reported in exclusively breastfed infants (3), the concentration of cowÕs milk protein is several magnitudes less, which might explain the fact that the presented cases tolerated breast milk without modification of the motherÕs diet. We conclude that even if HM is the preferred alimentation for premature babies, added supplements might expose the susceptible infants to high concentrations of allergens, such as nonhydrolyzed cowÕs milk protein. A. M. N. is supported by a fellowship from the Fonds de la Recherche en Sante´ du Que´bec. *Research Center, CHU Ste-Justine Department of Pediatrics University of Montre´al 3175 Coˆte Sainte-Catherine Montre´al, QC H3T 1C5 Canada Tel.: +1 514 345 4931 ext. 3971 Fax: +1 514 345 4801 E-mail: anne-monique.nuyt@recherche ste-justine.qc.ca Accepted for publication 19 April 2009 Allergy 2009: 64:1690–1691 Ó 2009 John Wiley & Sons A/S DOI: 10.1111/j.1398-9995.2009.02110.x References 1. Faber MR, Rieu P, Semmekrot BA, Van Krieken JH, Tolboom JJ, Draaisma JM. Allergic colitis presenting within the first hours of premature life. Acta Paediatr 2005;94:1514–1515. 2. Kvenshagen B, Halvorsen R, Jacobsen M. Adverse reactions to milk in infants. Acta Paediatr 2008;97:196–200. 3. Vandenplas Y, Koletzko S, Isolauri E, Hill D, Oranje AP, Brueton M et al. Guidelines for the diagnosis and management of cowÕs milk protein allergy in infants. Arch Dis Child 2007;92:902– 908. Supplements added to human milk might expose infants to allergens such as cowÕs milk protein. ALLERGY Net 1690 Ó 2009 John Wiley & Sons A/S Allergy 2009: 64: 1686–1696