Figure 1.

The origins of the concept of co-inhibition. The tripartite inactivation model³⁰ proposed that B cells are inactivated by antibody bound to antigen via the co-aggregation of the B cell antigen receptors with a receptor for the Fc portion of antibody. The model predicted the presence of negative signaling Fc receptors on B cells and that B cells are tolerized not by antigen receptor signals but instead by the co-operative signaling of antigen and Fc receptors. Reprinted with kind permission of Springer Science and Business Media. From page 611 in: Lindahl-Kiessling K, Aim G, Hanna MG, (eds.,). Morphological and Fundamental Aspects of Immunity, pp. 609–15. New York: Plenum Press 1971.