The clinical outcome of
peanut allergy and some factors associated with development of
peanut allergy remain unsolved. It has not been clarified to what extent peanut intake affects
immunoglobulin (
IgE) antibody formation in peanut sensitized individuals. The aim of the study was to investigate the development of
peanut hypersensitivity in children and adolescents with specific
IgE antibodies to peanut, using questionnaires and current serum tests and comparing it to information obtained 5-6 yr earlier, to investigate how peanut intake during this period related to subject age,
IgE antibody levels and symptoms and to investigate what information this patient group was given at the time of diagnosis regarding avoidance of peanut related food. All patients with detectable peanut-specific
IgE antibodies investigated during 1994-1996 deriving from two
allergy laboratories in the western region of Sweden were traced and reinvestigated (n=132). A total of 111 subjects (63 with
peanut allergy and 48 peanut sensitized) participated in the questionnaire. Eighty-six of them consented to be enrolled in a further interview and renewed testing of specific
IgE antibody to peanut 5 yr later. All tests were done using the Pharmacia CAP system. Increased
IgE antibody levels during follow-up was related to age; subjects 0-6 yr at initial test occasion were more likely to have higher
IgE antibody class than the older individuals (p=0.018). Exposure to peanut during the study, i.e. 5-6 yr since diagnosis, did not seem to affect the result. During the follow-up period, 29 out of 86 (34%) increased their
IgE antibody class. At the second test occasion the remaining subjects had similar (28%) or lowered (38%) levels of
IgE antibodies. Exposure to peanut during follow-up was more common in subjects with
IgE antibody class 1-3 compared to subjects with high value (> 3) at the initial test (p=0.003). Reported symptoms during follow-up were also more common in subjects with initially high
IgE antibody value. Individuals with initially high
IgE antibodies to peanut had been given more information about
peanut allergy and cross-reacting
allergens than other individuals. The subjects over 6 yr of age showed a decrease in peanut-specific
IgE class over a 5-yr period. Together with the literature, our result suggest that follow-up and renewed testing is recommended, since there may be a change in
IgE antibody classes and clinical sensitivity over time. Even in Sweden, with a low consumption of peanuts, the youngest individuals with peanut sensitization experienced a similar course of events that has been reported in other countries.