Abstract
Analogies in considerable detail hold between essential characteristics of classical conditioned defensive reflexes and immune reactions. The analogies become evident when combined conditioned and unconditioned stimuli are formally set into correspondence with combined hapten and carrier immunogens. Learning is elaborated also in the immune system when the transfer of information from the unconditioned to the conditional immuno-stimuli concurrently occurs. The analogies are regarded as having been evolved by adaptation of fundamentally parallel functions for survival against attack or invasion in the course of evolution, one on the macro- and the other on the micro- or molecular scale.