克隆选择（Clonal selection）又称株落选择，于1957年由澳大利亚的伯内特提出。他认为免疫细胞可以随机生成多样性的克隆，每一个免疫细胞的克隆表达针对某一个特定抗原的特异性的（Specific）受体（Receptor）。对于某一特定抗原，该抗原与表达其特异性受体的免疫细胞发生特异性结合，导致此种免疫细胞被活化并大量扩增。不同的抗原活化不同的免疫细胞克隆。免疫耐受（Immunological tolerance）是由于免疫细胞克隆发生了夭折，即与自身抗原结合的免疫细胞在扩增的前体细胞（Precursor or Progenitor）阶段发生了流产。

Clonal selection theory is a scientific theory in immunology that explains the functions of cells (lymphocytes) of the immune system in response to specific antigens invading the body. The concept was introduced by an Australian doctor Frank Macfarlane Burnet in 1957 in an attempt to explain the formation of a diversity of antibodies during initiation of the immune response. The theory has become a widely accepted model for how the immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens.