THE MAINTENANCE OF SELF-TOLERANCE

Two signal models for lymphocyte activation build on the Talmage/Burne t concept that receptor diversity is generated within the immune syste m by a random process, and that individual lymphocytes carry a single receptor on their surface that determines their specificity. Such mode ls cannot use a concept of signal one anergy (or deletion) to explain the maintenance of self-tolerance in terms of the Bretscher/Cohn theor y if they abandon the concept of associative recognition.