Tolerance to extensively heated milk in children with cow's milk allergy.

BACKGROUND Cow's milk allergy is the most common childhood food allergy. Previously we noted that children who outgrew their milk allergy had milk-specific IgE antibodies primarily directed against conformational epitopes; those with persistent milk allergy also had IgE antibodies directed against specific sequential epitopes. OBJECTIVE Because high temperature largely destroys conformational epitopes, we hypothesized that some children with milk allergy would tolerate extensively heated (baked) milk products. METHODS Children with milk allergy were challenged with heated milk products; heated milk-tolerant subjects were subsequently challenged with unheated milk. Heated milk-tolerant, unheated milk-reactive subjects ingested heated milk products for 3 months and were then re-evaluated. Immune responses were assessed in all subjects; growth and intestinal permeability were followed in heated milk-tolerant subjects. RESULTS One hundred children (mean age, 7.5 years; range, 2.1-17.3 years) underwent heated milk challenges. Sixty-eight subjects tolerated extensively heated milk only, 23 reacted to heated milk, and 9 tolerated both heated and unheated milk. Heated milk-reactive subjects had significantly larger skin prick test wheals and higher milk-specific and casein-specific IgE levels than other groups. At 3 months, subjects ingesting heated milk products had significantly smaller skin prick test wheals and higher casein-IgG(4) compared with baseline; other immunologic parameters, growth, and intestinal permeability were not significantly different. Heated milk-reactive subjects had more severe symptoms during heated milk challenge than heated milk-tolerant subjects experienced during their unheated milk challenge. CONCLUSION The majority (75%) of children with milk allergy tolerate heated milk.