Active sensitization does not increase the responsivity of rat peritoneal mast cells to diverse chemical stimuli.

Peritoneal mast cells from specific pathogen-free rats that had been sensitized to the nematode Nippostrongylus brasiliensis released histamine in a dose-dependent fashion on challenge with antigen, anti-rat IgE, anti-rat IgG and concanavalin A. Cells from non-sensitized animals showed weak or insignificant responses to these agents. However, the two preparations did not obviously differ in their reactivity to a range of pharmacological agents including ATP, dextran, polyamines and calcium ionophores. Both populations were refractory to cholinergic stimulation. These results show that active sensitization does not per se lead to a global increase in mast cell reactivity or releasability.