Allergy in the Mediterranean area. III: Cross reactivity among Oleaceae pollens.

Pollens of closely related species often share common antigens and allergens although this is not always the case. Four species of Oleaceae pollens commonly found in the Mediterranean area were investigated for cross-reactivity: olive (Olea europaea), ash (Fraxinus exselsior), privet (Ligustrum vulgare) and Phillyrea angustifolia, a common bush. Twenty individual sera of patients allergic to Oleaceae were investigated for specific IgE antibodies against the four species of Oleaceae pollens. The results indicated a high degree of correlation between RAST titres of Oleaceae pollens but three gave a particular emphasis on one species only. Cross-reactivity among these four pollen species was sought by means of RAST inhibition, iso-electric focusing and tandem cross-immunoelectrophoresis. All tests revealed a high degree of cross reactivity although there is no total identity among these four pollen species.