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

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).