Nature of the mast cell-macrophage interaction in immediate hypersensitivity.

The experiments discussed above indicate that during immediate hypersensitivity reactions, macrophages are stimulated by mast cells to synthesize PGE2 and 6-keto-PGF1 alpha but not LTC4. The arachidonic acid utilized for these products is mobilized from the macrophages itself and not shuttled from the mast cells. The stimulus for the involvement of the macrophage does not appear to be a direct cell interaction between the two cell types or a soluble factor released by the mast cells. Since the profile of eicosanoids produced by macrophages when exposed to mast cell granules is similar to that observed in the contribution of macrophages to immediate hypersensitivity reactions, mast cell granules appear to be responsible for the recruitment of macrophages to this reaction.