The Role of Mast Cells and Their Mediators in IgG-Antigen Complex-Mediated Inflammation

The strategic localization of mast cells near blood vessels led us to investigate the involvement of these cells in IgG-antigen complex-mediated inflammation, using mast-cell-deficient mice and their congenic controls. Mast cells were extensively degranulated and contributed to neutrophil influx, plasma exudation, fibrin deposition, edema formation, and tissue damage. Leukotrienes and the tumor necrosis factor (TNF) from mast cells participated in neutrophil elicitation, and histamine and leukotrienes in plasma exudation, fibrin deposition, and edema formation. Reconstituting the deficient mice with mast cells restored the responses, confirming the role of mast cells and their mediators. Studies with decomplemented and C5-deficient mice indicate that mast cells were stimulated by complement early in the reaction and later by an unknown mechanism. The findings show that mast cells and their mediators, such as leukotrienes, histamine, and TNF, play an important role in the initiation of IgG-antigen complex-mediated inflammation.