Definition: Cross-reactivity is the ability of the immune system to recognize similarities between different allergens, such that allergic antibodies produced against one allergen will also react against another, similar allergen.
Examples: There is a significant amount of cross-reactivity among different shellfish; a person who is allergic to one type of shellfish, such as shrimp, is very likely to also be allergic to another type, such as lobster or crab.
