Inhibition of the late phase reaction to anti-IgE by previous mast cell activation with compound 48/80.

The concept of an obligate association between mast cell activation and development of a late phase reaction (LPR) to various agents in human skin was further elucidated. Skin sites were treated four times at 24 h intervals with non-LPR-inducing doses of the histamine liberator compound 48/80 in 10 volunteers. The previously compound 48/80-challenged sites responded with an approximately 40% attenuated early response (P less than 0.01) and a 70% reduction of the LPR (P less than 0.001) to subsequently injected anti-IgE as compared with simultaneous reactions at control sites. The data suggest that mediators from the cutaneous mast cells are necessary for the final expression of an LPR.