The skin prick test and nasal provocation test with individually prepared flour extracts in patients with bakers' rhinitis and asthma

The reliability of skin prick tests (SPT) may be insufficient for the scree ning of occupational inhalant allergies. The influence of different flour e xtracts on the SPT in flour allergic subjects has not been compared previou sly. In this study, SPT reactions against two commercially available rye an d wheat flour extracts and individually prepared extracts from flour sample s were compared in 35 patients with known bakers' rhinitis. Flour sensitiza tion was confirmed by a positive nasal provocation test (NPT) and/or serum- specific IgE. The sensitivity of NPT with a combination of rye and wheat fl our extracts of individual flour samples was 94%. Wheat and/or rye flour sp ecific IgE (RAST greater than or equal to 2) was true positive in 86%. The sensitivity of the SPT was 94% for individual rye flour extracts compared t o 38% and 59% for two commercially available rye flour extracts and 88% for individual wheat flour extract compared to 53% and 48% for commercially av ailable wheat flour extracts. SPT and sIgE did not reveal a significant dif ference in prevalence between rye and wheat flour sensitization. Thirty hea lthy volunteers served as the control group. Three control subjects with hi stamine equivalent SPT reactions to grass pollen had a positive SPT reactio n against individual flour extracts, whereas NPT with undiluted individual flour extracts was negative in all controls. SPT with individually prepared flour extracts appears to be sensitive for the demonstration of inhalant f lour allergy. Our findings show that extracts of individual flour samples r ather than commercially available extracts should be used for both SPT and NPT if flour allergy is suspected.