Comparison of Mus musculus (rodent) antigen specific IgE test results on sensitive asthmatics from two different...

A series of asthmatics with known sensitivity to Mus musculus (rodent) antigen were compared to non-sensitive asthmatics and normal, nonatopic controls by the Fadal/Nalebuff Modified RAST (F/N RAST) protocol in an attempt to duplicate the results of a similar study in the Cook County Hospital. Two lots of extract material were used in the preparation of the reagent discs. A significant difference was observed between the results obtained on the two lots of extract but not between the results found at Cook County Hospital and Immunodiagnostic Research Foundation when the freshly extracted preparation was used. No clinically positive patient was scored as negative on the F/N RAST system when the fresh extract was used and no clinically negative individual was scored as positive. The over-all concordance of results at the two institutions was 74%, with 26% being equivocal. One patient, originally evaluated as skin test negative, was later re-evaluated and found to be 3+ positive after Immunodiagnostic Research Foundation reported a Class 4 RAST score. These results appear to confirm the findings of Lim and Ganju that rodent antigen causes the formation of specific IgE antibodies in sensitive asthmatics.