An immunologic network.

The immune system is a complex network of molecules and cells specifically connected by the complementarity of receptors for antigen and receptors for receptors. The network includes multiple positive- and negative-feedback loops, which modulate the type, magnitude, and duration of responses. The great challenge is to devise ways to manipulate the system specifically to induce effective autoimmunity to cancer, to prevent allograft rejection, and to turn off undesirable responses in allergies and autoimmune diseases. Recognition of the immune system as a network helps to explain why these objectives are so difficult and why manipulation of multiple components to achieve desired regulation may be required. But presumably manipulation must be focused on connectivity between receptor for epitope and receptor for receptor to achieve a high degree of specific regulation.