Assessment of sensitization to holm oak (Quercus ilex) pollen in the Mérida area (Spain).

Sensitization to Quercus ilex (holm oak) was studied in 760 patients with clinically suspected sensitization to aeroallergens. Prick tests with commercial extracts of Q. ilex proved positive in 27 patients; none were monosensitive. Nasal and conjunctival provocation tests and specific IgE (RAST) performed with Q. ilex extracts in these patients were negative in all but one patient, who exhibited specific IgE titer (by RAST) of 7 PRU/ml (class 3). We conclude that Q. ilex pollen, though obtained in considerable quantities by our collector, does not cause allergies in our area.