Humoral immune response to cow's milk in children with cow's milk allergy. Relationship to the time of clinical response to cow's milk challenge.

In 47 infants and children aged 4-66 months with clinically proven cow's milk allergy and in a group of age-matched controls, serum IgG, IgA and IgM cow's milk-specific antibodies were determined with ELISA assays while IgE cow's milk-specific antibodies were measured with Pharmacia RAST. The patients were divided into three separate groups according to the time of clinical response to a standardized cow's milk challenge protocol. Immediate reactions (less than 45 min after challenge), which were mainly accompanied by urticarial skin eruptions, were associated with elevated IgE milk-specific antibody levels, indicating the involvement of an immediate hypersensitivity mechanism. Alternatively, intermediate reactions (1-20 h after challenge), which were mainly accompanied by vomiting and diarrhea, were not IgE-mediated. In the late reactions (greater than 20 h after challenge) both eczematous and gastrointestinal reactions were seen. Patients with eczematous eruptions also showed elevated IgE milk-specific antibody levels. IgG milk-specific antibody levels were similar in each of the patient groups but all groups were significantly lower than in the controls. Levels of IgA and IgM milk-specific antibodies were similar in patients and controls. The results indicate that different immunopathogenic mechanisms are operative in these subgroups of patients with cow's milk allergy.