Challenge testing in children with allergy to cow's milk-proteins

Abstract

To evaluate clinical response after challenge testing in infants with allergy to cow's milk proteins at diagnosis and again when these infants were aged 1 year old and had been fed an exclusion diet. We performed a prospective study of 49 infants aged less than 6 months with a clinical history suggestive of cow's milk protein allergy, positive skin prick test and specific IgE for alpha-lactalbumin, beta-lactoglobulin and casein. In all children challenge test with cow-milk adapted formula was carried out at diagnosis. The same procedures were repeated when the children were aged 1 year but challenge testing was repeated only in children with a negative skin prick test and specific IgE antibodies to cow's milk proteins. At diagnosis, challenge tests produced immediate hypersensitivity reactions in 94% of infants. Late reactivity (i.e., more than 2 hours after challenge) was found in only 6% of infants, all of whom presented dyspepsia. When the infants were aged 1 year, and after results of immunological study were negative, a further challenge test was performed in 24 (49%) of lactating infants included in the study. Of these 24 infants, positive challenge was found in 5 (21%). None of the infants presented immediate symptomatology (clinical features appeared 7 days after the reintroduction of cow's milk proteins). Ninety-four percent of challenge tests performed at diagnosis provoked immediate reactions. The results of challenge tests after a negative skin prick test in children with normal concentrations of specific IgE were positive in 21% infants, who presented late reactivity (a mean of 7 days after milk ingestion).