Human serum IgE-mediated mast cell degranulation shows poor correlation to allergen-specific IgE content


Dr Ulrich Blank
INSERM E 0225, Faculté de Medicine X. Bichat
16 rue Henri Huchard, BP 416
75870 Paris Cedex 18


Background:  Although allergen-specific IgE content in serum can be determined immunochemically, little is known about the relationship between this parameter and the strength of the degranulation response upon allergen triggering.

Objectives:  Analyse the degranulation capacity of immunochemically defined purified and serum IgE after challenge with anti-IgE or allergen using a rat mast cell line (RBL) transfected with the α-chain of the human high-affinity IgE receptor (FcɛRI).

Methods:  Purified IgE specific for 4-hydroxy-3nitrophenylacetyl, purified IgE of unknown specificity, and sera from allergic patients sensitive to Dermatophagoides pteronyssinus and Dactylis glomerata were assessed. Degranulation was measured by a β-hexosaminidase release assay after anti-IgE or allergen-specific challenge.

Results:  For purified monoclonal IgE a significant correlation (r = 0.97) was found between the proportion of bound allergen-specific IgE and the strength of the degranulation response. In contrast, no correlation (r = 0.27) was detected after sensitization with serum IgE.

Conclusion:  Our studies demonstrate that mast cell activation mediated through IgE from allergic patients is a result of complex relationships that are not only dependent on allergen-specific IgE content but also relate to the capacity to efficiently sensitize and trigger the signalling responses that lead to degranulation.