Characteristics of histamine release from isolated rat mast cells: differences when various ligands are used to...

Differences are reported in the response of rat peritoneal mast cells to three releasing agents: ovalbumin, to which the rats were actively sensitized, anti-IgE, an immunoglobulin directed against the rat IgE molecule, and IgE chemically dimerized with suberimidate. Both the rate of histamine release and the rate of desensitization were measured for each of the three ligands. The calculated doubling times for the rates of histamine release due to ovalbumin, anti-IgE and dimer were 19.6 sec, 168 sec and 37.7 sec respectively. The calculated half-lives for the rate of desensitization due to ovalbumin, anti-IgE and dimer were 348 sec, 5900 sec and 3450 sec respectively. The three ligands are all believed to act by crosslinking Fc receptors on the cell surface but the pattern of responses obtained varied with the ligand used. It is proposed that some component of the transduction mechanism linking the stimulus to the cell to the subsequent response can distinguish between the various sizes or conformations of Fc receptor aggregates formed on the cell surface.