Acute Urticarial Reactions to Cow's Milk in Infants Previously Fed Breast Milk or Soy Milk

Twenty-nine breastfed or soy formula-fed infants with IgE-mediated sensitization to cow's milk (CM) were identified because they had acute urticarial reactions while being fed CM for the first time. One of these infants had a reaction to CM in the newborn nursery, suggesting in-utero sensitization. Sixteen other infants inadvertently had been fed CM in the newborn nursery without reaction, suggesting that this was their initial sensitizing event. The remaining 12 may have been sensitized by small amounts of CM antigens either in utero or via breast milk. The clinical condition is characterized by elevated serum IgE levels; positive RASTs to alpha-lactalbumin (AL), beta-lactoglobulin (BL) and casein (C) and a high frequency (16/29, or 55%) of recurrent wheezing. The important role of heredity in the development of this entity is demonstrated by its occurrence in identical twins and in HLA-identical siblings, and by the high frequency of allergy in 28 parent pairs (89%) and in 56 parents (70%). Although the condition appears to be clinically homogeneous, genetic homogeneity could not be demonstrated by HLA-typing. There was not increased frequency of any HLA-A, HLA-B, or HLA-DR phenotype either in the patient group or in the parent group.