Immunogenetic analysis of the heavy chain variable regions of IgE from patients allergic to peanuts

Peanuts are one of the most allergenic of the foods, and hypersensitivity responses to peanut allergens can be fatal. Although the nature of the antigenic components of peanuts is being defined at the molecular level, there is little information on the induced IgE antibodies, which are central to the allergic reaction. Recognition sites of IgE antibody molecules arise from the variable regions of heavy and light chains (V-H and V-L). By using nested polymerase chain reactions with specific primers for the available repertoire of V-H genes, together with primers in the constant epsilon region, we have amplified V-H sequences of IgE from blood lymphocytes of two patients with peanut allergy. After cloning and sequencing the products, we found a predominance of V(H)1 family use in both patients, which was not found in control IgM-specific primers. The IgE V-H sequences were highly somatically mutated, but in only six of 17 cases was there clear evidence for clustering of amino acids indicative of antigen selection. Previous results from patients with allergy to house dust mites have indicated predominance of V(H)5 use and little evidence for antigen selection. Although results from two patients allergic to peanuts must be regarded as preliminary, they do suggest that the IgE response to peanuts may have a different V-H bias, with a similar mutational pattern.