Central versus peripheral tolerance: clonal inactivation versus suppressor T cells, the second half of the 'Thirty Years War'.

The period of intellectual history of immunology that we wish to treat began some 30 years ago, in 1958, when the features of immune tolerance had already been described (Billingham, Brent & Medawar, 1953), but mechanisms remained difficult to fathom. The subsequent 30 years in quest of the key(s) to tolerance can be roughly divided into the pre-T-cell suppression half, and the years from 1973 to 1988 in which the major rival to ideas of clonal deletion or abortion has been the T-suppressor cell.