The incidence of cross-stimulations by natural allergens was investigated using RBL-2H3 cells sensitized with five different mouse monoclonal anti-DNP IgEs and four mercury-induced rat monoclonal IgEs. Cells sensitized with 3 of the 5 monoclonal anti-DNP IgEs (clones SPE-7, SRT-1, LB4) responded by serotonin release upon stimulation by natural allergens such as Dermatophagoides pteronyssinus, horse dander and mugwort extracts. Serotonin release could be inhibited by monovalent DNP-lysine, indicating the involvement of DNP-binding sites of IgEs. Two of the clones (LO-DNP-30 and LA2) were negative on all tests with allergens. All but one (Hg32) of the mercury-induced rat IgE monoclonal antibodies tested positive with DNP-BSA, and with at least one of the six allergen extracts. IgE clone Hg12 mediated serotonin release with 5 of the 6 allergens tested.
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