Identification of histamine releasing factor(s) in the late phase of cutaneous IgE-mediated reactions

We have shown that fluids collected from antigen-challenged skin blisters during the late phase reaction cause the release of substantial amounts of histamine χ̄ = 42%, n = 14) from human basophils in vitro. Control fluids collected either during the immediate phase or from an unchallenged blister released ≤10% histamine from both phasophils and lung mast cells. Late phase blister fluids induced low levels of histamine release from human lung cells (χ̄ = 11%, n = 4) that were slightly but not significantly greater than levels induced by control blister fluids. The characteristics of basophil release were similar to IgE-mediated stimuli in dose dependence, calcium and temperature requirements, and kinetics. The IgE dependence of the late phase blister fluid was demonstrated by desensitization of the basophils to anti-IgE, which obviated the response to anti-IgE and blister fluid but did not affect a non-IgE-mediate stimulus. Removal of the cell surface IgE with lactic acid also abolished the response to both anti-IgE and late phase blister fluid. Incubation of the 'stripped' cells with serum containing IgE myeloma restored the response to anti-IgE but failed to affect response to late phase blister fluid. The characteristics of release obtained with this factor closely resemble those of an IgE-dependent histamine releasing factor from cultured macrophages previously described by our group.