Autoimmune disease and the theory of clonal abortion. Is it still relevant?

Explanations for self-tolerance and its failure in autoimmune disease remain conjectural. Earlier deletional theories and the later clonal abortion theory as a basis for central B-cell (and possibly T-cell) tolerance seemed to conflict with various experimental and clinical observations, including those relating to the ability to induce autoimmune reactivity in normal adult animals. Accordingly, immunoregulatory controls have dominated discussions. However, there is recent compelling experimental evidence in favour of clonal abortion of B lymphocytes in the absence of T-cell help. It is proposed that two sets of regulatory systems operate at different stages in life to establish and maintain self-recognition: a central tolerance operates through clonal abortion during embryonic and early postnatal life and during childhood and beyond, ancillary regulatory systems deal with the self-reactive cells which emerge in a milieu in which helper influences interfere with clonal abortion.