1978 Volume 21 Issue 3 Pages 211-218
The present study was designed to provide a means of diagnosis of insulin allergy by the radioallergosorbent test (RAST), an in vitro method for the detection in serum of reaginic (IgE) antibodies against specific antigens. A positive RAST reaction was defined in the study as being more than twice the mean percent bound radioactivity obtained with 10 control sera. (% bound radioactivity: 4.5±0.3%).
With sera from 18 non-allergic diabetics treated with insulin, negative results were obtained (% bound radioactivity: 5.4±0.3%). With sera from 2 diabetics with insulin allergy, positive results were obtained (% bound radioactivity: 16.6%, 13.0%). Plots of the percent bound radioactivity against the logarithm of allergen concentration indicated that the response to increasing allergen concentration was almost linear.
In the 50% RAST inhibition measures, the percentage of bound radioactivity decreased, after preincubation of the sera with cold allergens. These results suggest that the RAST reaction may be almost allergen specific.
We attempted to eliminate the allergenic potency of insulin components by 50% RAST inhibition measures.
The following results were obtained.
1) Using paper discs coupling crude insulin, the amounts of a- and b-components (inhibitors) required to give 50% inhibition in the RAST were about 2 mg.
2) Using paper discs coupling crude insulin, the amount of purified insulin (inhibitor) required to give 50% inhibition in the RAST was more than 50 mg.
These results support the possibility that purified insulin is less allergenic than the a- and b-components.