Multiple pollen sensitization: a molecular approach to the diagnosis.

BACKGROUND

Sensitization to multiple pollen species is a frequent diagnostic event. Several allergenic molecules with a high level of homology have been identified in divergent pollen families and named panallergens.

METHODS

We sought to define the criteria to evaluate the prevalence of the multiple pollen sensitization, to identify specific markers of this condition, and to correlate them with the underlying allergic disease. Patients presenting an allergic respiratory disease underwent skin testing with 23 pollens. Patients fulfilling predefined selection criteria were grouped and classified as having multiple pollen sensitization. Patients in each subgroup were tested for IgE to rBet v 2, rJun o 2, rBet v 1, rPhl p 5 and bromelain. Demographical, allergological and clinical data were recorded in the subgroup of patients with multiple pollen sensitization.

RESULTS

Seventeen percent of the pollen-sensitized patients formed the multiple pollen-sensitized subgroup. These subjects were positive for most of the pollen species tested regardless of known exposure to them. None of the subjects sensitized to less than six pollen species were positive to panallergens, whereas 55% of the sera of the multiple pollen-sensitized group were positive to rBet v 2, and 15% to rJun o 2. IgE to rBet v 1 and rPhl p 5 were found positive in all the subgroups. Age, gender, bronchial asthma, oral allergy syndrome, skin test reactivity and previous specific immunotherapy differed significantly when these two subsets were considered.

CONCLUSIONS

Allergy diagnosis based on allergenic molecules is crucial in the patient with multiple pollen sensitization. This condition appears to be determined by the sensitization to defined allergenic components (panallergens) rather than by pollen of multiple species as such. Detection of IgE to nonpanallergenic molecules allows to identify more relevant allergenic sources. Clinical aspects of the underlying allergic disease (e.g. asthma and oral allergy syndrome) seem to be differently related to IgE reactivity to panallergens.