The promiscuity of immunoglobulin E binding to peanut allergens, as determined by Western blotting, correlates with the severity of clinical symptoms.

ABSTRACT

BACKGROUND: IgE binding to a specific protein has been shown to be associated with severe anaphylaxis to hazelnuts; however, the relationship between IgE binding to specific peanut allergens and symptom severity is currently unclear. OBJECTIVE: To determine if the pattern of IgE binding to specific peanut allergens is associated with the severity of clinical symptoms. METHODS: Forty peanut allergic patients underwent a double-blind placebo-controlled low-dose peanut challenge, during which the severity of the patients' peanut allergy was scored. Serum peanut-specific IgE (psIgE) was measured and IgE binding patterns to peanut proteins analysed. RESULTS: Seventeen IgE binding bands were identified between 5 and 100 kDa with eight bound by >50% of patients. The total number of bands per patient correlated significantly with challenge score (P=0.001, r=0.505) and psIgE (P<0.001, r=0.820). Cluster analysis failed to reveal any association between a particular protein or pattern of proteins (based on presence/absence) and challenge score. However, two protein bands ( approximately 43 and 41 kDa) had peak intensities that correlated positively with challenge score and a third band ( approximately 48 kDa) that correlated negatively. The bands were identified as subunits of Ara h 3/4 and 1, respectively. CONCLUSIONS: Promiscuity of IgE binding appears more important than the recognition of individual proteins. This may mean that clinically useful specific immunotherapy for peanut allergy will be difficult to achieve if only selected allergenic proteins are used. Further investigation of Ara h 1 and 3/4 subunits and a possible association with symptom severity are also highlighted by this study.