Selective reaction of the body to substances that are foreign to it, or that the immune
system identifies as foreign, shown by the production of antibodies and
antibody-bearing cells or by a cell-mediated hypersensitivity reaction.
Source:
PAC, 1993, 65, 2003
(Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993))
on page 2058