Immunity

A state of resistance or refractoriness resulting from responses by an organism to the invasion of substances foreign to that organism. Immunity results from the production of antibodies matching, nearly one-to-one the foreign substances present. Whereas immunity refers to a state in which certain material substances are no longer disruptive, adaptation refers to a state in which information in the form or disturbances no longer affects certain essential variables. (Krippendorff )