Burnet: Clonal selection hypothesis A single progenitor cell gives rise to a large number of lymphocytes, each Pool of mature naive lymphocytes with a different specificity foreign antigen Proliferation and differentiation of activated specific lymphocytes to form a clone Removal of potentially self-reactive of effector cells immature lymphocytes by clonal deletion Effector cells elim nate antigen self antigens solf antigensBurnet: Clonal selection hypothesis