Regulation of mast cell secretory response to the type I Fcepsilon receptor: inhibitory elements and desensitization

While the current understanding of the stimulus-response coupling networks triggered by the multi-chain immune-recognition receptors (MIRRs) has markedly advanced, knowledge of its control mechanisms is only emerging. Regulation of the secretory response of mast cells to the stimulus provided by the type I Fcepsilon receptor (FcepsilonRI) is our topic of interest. Several mast cell membrane receptors capable of inhibiting both immediate and late responses have so far been identified. However, their ligands and mechanism(s) of operation are only partly known. Moreover, desensitization of mast cells' response to the FcepsilonRI, a well-known and widespread control process of many neural or hormone receptors, is hardly understood in this case. In this brief report we describe results of recent experiments in which we studied both of these aspects of mast cells' response to the FcepsilonRI stimulus by an inhibitory receptor MAFA, as well as those where we have established that these cells are susceptible to physiological modes of FcepsilonRI desensitization caused by prolonged exposure to sub-threshold concentrations of FcepsilonRI clustering agents.