Multichain immune recognition receptor signaling: different players, same game?

The cells of the immune system respond to their environment through an array of signaling receptors. Key among these, are the family of multichain immune recognition receptors (MIRRs), including the T-cell and B-cell receptors, and the high-affinity IgE receptor expressed by mast cells and basophils. These receptors are complexes composed of ligand-binding domains associated with signal-transducing subunits. The biochemical cascades triggered by MIRRs are understood in significant detail, however, the mechanism by which antigen binding initiates signaling is not known. In this Opinion, a novel mechanistic model for the MIRR-mediated signaling is proposed. The model assumes that this process is triggered and controlled by homo-oligomerization of signal-transducing subunits. Principles learned in this model have important implications for immune response in general.