Cross-reacting allergens in natural rubber latex and avocado.

BACKGROUND

An association between allergy to latex and avocado has been reported but the responsible cross-reacting allergens have not been identified or characterized.

METHODS

Immunoblotting, immunoblot inhibition, and RAST inhibition methods were used to study cross-reactive proteins between natural rubber latex (NRL) and avocado. Sera from 18 patients with previously verified latex allergy were used as the source of IgE antibodies, and 11 of the patients underwent skin prick testing 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 were used as soluble inhibitors, binding of IgE antibodies to solid-phase avocado proteins was inhibited in a dose-dependent manner: 100 micrograms of NRL proteins inhibited IgE binding to 15 of the 17 avocado proteins, and 10 micrograms caused inhibition to 13 protein bands. Comparably, soluble avocado proteins were able to inhibit IgE binding to solid-phase NRL. Corresponding RAST inhibitions were performed with two patient sera; in both, avocado inhibited IgE binding to NRL and in one NRL proteins inhibited IgE binding to avocado. Skin prick test responses to fresh avocado were positive in seven of the 11 patients with latex allergy who were tested.

CONCLUSIONS

The large number of inhibitable proteins in immunoblot experiments and clinical observations from skin prick tests suggest considerable immunologic cross-reactivity between NRL and avocado. The observed cross-reacting protein components may be responsible for the recently reported type I hypersensitivity reactions to NRL and avocado in patients with a preexisting allergy to either allergen.