AN IMMUNOPHARMACOLOGICAL STUDY OF THE BIPHASIC ALLERGIC SKIN REACTIONIN MICE

Biphasic skin reactions, with peaks at 1 and 24h after epicutaneous ch allenge with antigen (immediate phase response: IPR and late phase res ponse: LPR, respectively), were induced in ddY, ICR, Balb/c and Balb/c -nu/nu mice passively sensitized with monoclonal IgE antibody 24 h bef ore. In WBB6F(1)-W/W' mice, which lack mast cells, only the LPR was ob served. The IPR was characterized by a rapid increase in capillary per meability and the LPR by skin thickening with significant infiltration of eosinophils and other inflammatory cells in Balb/c mice. Histamine H-1 receptor antagonists, including diphenhydramine and homochlorcycl izine, and the allergic histamine release inhibitors, tranilast and am lexanox, clearly inhibited the IPR, but not the LPR. Prednisolone and dexamethasone, however, inhibited both. Prednisolone also inhibited th e LPR in WBB6F(1)-W/W' mice. These results indicate that IgE antibody- dependent biphasic skin reactions consist of a mast cell- and histamin e-dependent IPR and a mast cell-independent LPR.