A COMPARATIVE-STUDY OF THE TRYPTASE RELEASE TEST AND THE CELLULAR ALLERGEN STIMULATION TEST (CAST) IN MITE SENSITIVE PATIENTS

Background The stimulation of blood basophils to release mediators in vitro is widely used for diagnosis of allergic diseases. Tryptase rele ase and sulphidopeptideleukotriene production are both triggered by cr oss-bridging of adjacent IgE molecules on the surface of IEE-bearing b asophils. Objective We have compared the sensitivity of tryptase relea se test (TRT) and cellular allergen stimulation test (CAST) which, res pectively, measure tryptase and sulphidopeptideleukotrienes that are p roduced upon cell stimulation by mite extracts. Methods Blood was take n from 247 patients with allergy to mites and 137 non-allergic control subjects. We measured tryptase release from basophils after allergen challenge in vitro by sandwich radioimmunoassay. The sulphidopeptidele ukotrienes production was quantified by an ELISA test based on a monoc lonal antibody which recognized leukotriene T4 (LTC4) and its metaboli tes LTD4 and LTE4.Results Our data show that both methods are equally effective to distinguish allergic patients from normal controls (P>0.0 001). There was a significant correlation between mite-specific serum IgE and CAST results (r = 0.69 for Dermatophagoides pteronyssinus; r=0 .73 for Dermatophagoides farinae). Correlations between IgE against mi tes and tryptase values appeared rather poor (r = 0.47 for Dermatophag oides pteronyssinus; 0.49 for Dermatophagoides farinae). Moreover, the data were used for the calculation of sensitivity, specificity, preva lence, and overall efficiency (Roc/Galen & Gambino analysis). The resu lts were as follows: 71%, 87%, 64%, 76% (CAST results for Dermatophago ides farinae); 64%, 78%, 53%, 70% (TRT results for Dermatophagoides fa rinae). Conclusion The partial discrepancies observed could be interpr eted as a consequence of conditions that were technically not optimal. False-positive results may be due to the action of some non-specific cytotoxic agent, false-negative results may be due to hyporesponsive b asophils or the low number of cells participating in the reaction and finally, in the case of TRT, to G4 monoclonal antibody to tryptase emp loyed.