clonal selection

in immunology
synonym: selection theory (in immunology)
https://doi.org/10.1351/goldbook.13016
Selection and activation by antigen of a lymphocyte, bearing a complementary receptor, which then proliferates to form an expanded clone.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1145 [Terms] [Paper]