CROSS-REACTING ALLERGENS IN NATURAL-RUBBER LATEX AND AVOCADO

Background: An association between allergy to latex and avocado has be en reported but the responsible cross-reacting allergens have not been identified or characterized. Methods: Immunoblotting, immunoblot inhi bition, and RAST inhibition methods were used to study class-reactive proteins between natural rubber latex (NRL) and avocado. Sera from 18 patients with previously verified later allergy were used as the sourc e of IgE antibodies, and II of the patients underwent skin prick testi ng with fresh avocado. Results: Fourteen of the 18 sera (78%) had IgE antibodies that bound to a total of 17 avocado proteins with apparent molecular weights ranging from 16 to 91 kd. Ten most strongly reacting sera were used for immunoblot inhibition studies. When NRL proteins w ere used as soluble inhibitors, binding of lgE antibodies to solid-pha se avocado proteins was inhibited in a dose-dependent manner: 100 mu g of NRL proteins inhibited IgE binding to 15 of the 17 avocado protein s, and 10 mu g caused inhibition to 13 protein bands. Comparably, solu ble avocado proteins were able to inhibit IgE binding to solid-phase N RL. Corresponding RAST inhibitions were performed with two patient ser a; in both, avocado inhibited IgE binding to NRL and in one NRL protei ns inhibited IgE binding to avocado. Skin prick test responses to fres h avocado were positive in seven of the II patients with latex allergy who were tested. Conclusions: The large number of inhibitable protein s in immunoblot experiments and clinical observations from skin prick tests suggest considerable immunologic cross-reactivity between NRL an d avocado. The observed cross-reacting protein components may be respo nsible for the recently reported type I hypersensitivity reactions to NRL, and avocado in patients with a preexisting allergy to either alle rgen.