IgE antibodies tests

In interpreting results of IgE antibody tests, ROC curves provide more information to aid discrimination between positive and negative results. The concentration of IgE antibodies assessed by immunoassay is related to the presence of allergic symptoms. 

Soderstrom L, Kober A, Ahlstedt S, et al. A further evaluation of the clinical use of specific IgE antibody testing in allergic diseases. Allergy. 2003 58 921-8. 

A2.2 IgE Antibody Tests for Diagnosis and Drug Aiiergen Studies... 

The specificity of assays for the detection of NMBD-reactive IgE antibodies in patients sera generally exceeds 90 % but the specificity may vary from around 50 % reaching a maximum of about 90 %. In one study of assay performance of radioimmunoassays for the detection of IgE antibodies to NMBDs a value of 100 % was obtained for the positive predictive value of a positive result. Skin tests remain the current reference test for NMBD-allergic sensitivity but their specificity is occasionally in question and their sensitivity sometimes less than expected. In addition, skin tests are said to be unreliable in the first 4-6 weeks after the reaction to an NMBD and certain medications may preclude their application in some patients. In these cases and in situations where skin tests caimot be employed, for example in attempts to assess a patient s allergic status before a completed operation or after a fatal reaction, IgE antibody tests on serum from blood samples taken at the time offer the only chance of obtaining the relevant diagnostic data. 

Table 7.9 Incidences of positive IgE antibody test for neuromuscular blocking drugs in the sera of a homogeneous group of patents who experienced an anaphylactic reaction during anesthesia. Comparison of the morphine immunoassay with immunoassays for individual drugs ...

Both skin and IgE antibody tests can be used to detect allergenic cross-reactivity between NMBDs but the frequency of cross-reactions is generally higher when determined by interaction... 

If appropriate OAD-reactive IgE antibody tests are available, they should be used as an adjunct to skin testing but an understanding of the immunochenucal basis of cross-reactivity between opioids and NMBDs shows that a cautionary approach to interpretation is necessary. For example, a morphine solid phase is routinely employed to detect NMBD-reactive IgE antibodies in the sera of subjects allergic to NMBDs (see Sect. 7.4.3.4.2). The structural basis of the cross-recognition is the tertiary methyl ammonium group of morphine and the substituted ammonium groups on NMBDs. 

Reactions can be distinguished by appropriately diluted skin tests with suspected drug(s) and specific IgE antibody tests... 

---