Results of skin test and RAST in allergy to a clinically potent allergen (castor bean).

In order to investigate once more the usefulness of the RAST procedure in the diagnosis of reaginic hypersensitivity, we studied a series of patients showing a well known sensitivity to castor bean, which is a potent antigen, and compared the results with those given by patients with no clinical allergy to this antigen as confirmed by negative skin testing. The latter group included patients with no contact, a remote contact or a close contact with castor bean. Castor bean allergy seems to be a good model in the testing of human reaginic hypersensitivity. We observed in the castor bean positive group of forty-one patients a 95% correlation between RAST positivity and skin test positivity with only two negative RAST scores, and in the castor bean negative group of ninety-four patients, a 97% correlation, with three RAST positive scores. For its specificity and its good sensibility (although lesser than skin testing), RAST can thus be recommended as a diagnostic tool as a complement to skin testing. Moreover, for potent allergens, RAST offers a risk-free diagnostic alternative.