IgE to penicillins with different specificities can be identified by a multiepitope macromolecule: Bihaptenic penicillin structures and IgE specificities

• We explore an immunoassay system to detect IgE with different specificities.
• We use a solid phase cellulose disc with one or two haptens.
• Bihaptenic solid phases improve the detection of IgE from cross-reactive patients.
• Bihaptenic solid phases do not decrease the binding of IgE from selective patients.
• Bihaptenic solid phases are useful for screening sera with different specificities.

Quantitation of specific IgE by immunoassay is a recommended in vitro test for the diagnosis of immediate hypersensitivity reactions to betalactams (BLs), particularly when skin test results are negative. IgE antibodies that recognize the common nuclear structure of all BLs or the specific side chain structure can be mainly distinguished by immunoassays. The aim of this study was to develop an immunoassay system to detect IgE antibodies with different specificities. Cellulose discs conjugated with benzylpenicillin (BP), amoxicillin (AX) or both drugs, with poly-l-lysine (PLL) as carrier molecule, were used as solid phases in the radioallergosorbent test (RAST). Direct and inhibition radioimmunoassay studies were made to verify the structures recognized by serum IgE antibodies from penicillin-allergic patients. Our results indicated that the addition of both haptens did not decrease the capacity to capture IgE when serum specific to either BP or AX was used, at least in terms of sensitivity. In addition, the inclusion of two haptens improved significantly the levels of IgE detection in patients who recognized both BP and AX. Therefore, the use of a solid phase with a carrier molecule conjugated with two determinants (AX and BP) is helpful to recognize IgE antibodies against either of these determinants and is useful for screening sera with different specificities.