[Food allergy in asthma. Diagnostic significance of peripheral eosinophils]

Thirty one patients with suspicion of asthma due to food allergy (lack of correlation between allergic sensitivity and asthmatic attacks, association of clinical features suggestive of food allergy, no response to the pharmacological treatment) received an elimination diet. A second group (control group) of 51 asthmatic patients were enrolled in the study for a better evaluation of the diagnostic significance of blood eosinophil counts in food-induced asthma. 29-31 patients who took a variable oligoallergenic diet had a baseline blood eosinophilia greater than 600/mm3 (range 600-2100/mm3). Eosinophil count after an appropriate diet showed an early significant fall which preceded the improvement of symptoms. Only 10 patients had not a valuable improvement from the diet. The post diet change of spirometric values was significant. There was no significant difference between subjects with an eosinophil count greater than 1000/mm3 vs. less than 1000/mm3 with regard to both inhalant and food skin prick tests. On the other hand, the group with blood eosinophilia greater than 1000/mm3 had a significant correlation with the presence of persistent asthma (persistent alteration of forced expiratory volumes verified in asymptomatic phases of the disease) as with the anamnestic or actual report of eczema or other clinical manifestations of food allergy. Blood eosinophil count showed to be essential in the management of patients with a suspicion of asthma due to food allergy.