Mast cell mediators regulate vascular permeability changes in Arthus reaction.

Plasma exudation characterizes the early phase of acute inflammation. The possible role of mast cells and their mediators in this event in immune complex-induced injury was studied. Dye exudation was assessed from 5 min to 2 hr after initiating reverse passive Arthus reaction in mast cell-deficient mice, WBB6F1-W/Wv (W/Wv), and their normal congenic controls, WBB6F1-+/+ (+/+). The response to antibody (10, 30 and 100 micrograms/site, i.d.) was dose- and time-dependent in both groups of mice. At the lower doses of antibody, 10 and 30 micrograms/site, exudation was significantly less (30% and 40%, respectively) in W/Wv as compared to +/+ mice between 15 to 45 min. With 100 micrograms of antibody/site, significant differences between W/Wv and +/+ mice were noted only at 15 and 30 min. The deficit in permeability changes in W/Wv mice was reversed by local mast cell reconstitution. In +/+ mice, pyrilamine and methysergide pretreatment reduced vascular permeability to the same extent by 70, 60 and 35% when stimulated for 30 min with 10, 30 and 100 micrograms of antibody/site, respectively. An equivalent inhibition was observed with the 5-lipoxygenase inhibitor A-63162. None of the inhibitors decreased plasma permeation in W/Wv mice. These results indicate that the mast cell mediators histamine and serotonin regulate vascular permeability early during an immune complex-mediated inflammation. The data also suggest the involvement of leukotrienes and the importance of mast cells in their synthesis. The profile of inhibition in +/+ mice agrees well with the difference in exudation observed between normal and mast cell-deficient mice.