Anaphylaxis to lemon soap: citrus seed and peanut allergen cross-reactivity

Many individuals allergic to peanuts have multiple allergen sensitivity.

To report the first case, to our knowledge, of a peanut allergic patient who exhibited cosensitivity to citrus seeds and who had experienced anaphylaxis to lemon soap.

Extracts of peanut and seeds from different varieties of citrus fruit (orange, lemon, and mandarin) were prepared and resolved with 14% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Direct and inhibition immunoblotting of the patient's serum on the extracts was used to examine the pattern of IgE reactivity and the presence of cross-reactive allergens.

Numerous IgE reactive proteins were demonstrated in each citrus seed extract and the peanut extract. Complete IgE cross-reactivity was demonstrated among the different citrus seed extracts. Partial cross-reactivity was demonstrated between the peanut and orange seed extracts.

Citrus seeds contain numerous IgE reactive proteins that are completely cross-reactive among orange, lemon, and mandarin. When peanut allergy coexists with citrus seed allergy, IgE cross-reactivity between peanut and citrus seed proteins can be demonstrated, suggesting a basis to this cosensitivity.