Insights into the IgE cross-sensitization and possible cross-reactivity patterns of sera reactive to chlorhexidine (CHX) are still incomplete and are likely to benefit from a functional exploration using a passive mast cells activation test (pMAT). Therefore, we want to study whether the pMAT with CHX-specific IgE (sIgE), enables to depict effector cell degranulation in response to alexidine (ALX), octenidine (OCT) and/or polyhexamethylene biguanide (PHMB) indicative of cross-reactivity between these compounds and CHX.
Serum of 10 CHX-allergic patients, 9 individuals with an isolated sIgE CHX and 5 healthy controls were included. Human cultured mast cells (MCs) were, before and after sensitization, challenged with CHX, ALX, OCT or PHMB. Degranulation was measured via quantification of up-regulation of CD63.
MC responsiveness to ALX and OCT was demonstrable with 4/10 and 3/10 of the sera of CHX-allergic patients, respectively. Percentage of degranulation varied between 12-34% for ALX reactive MCs and between 4-22% for OCT reactive MCs. No reactivity to ALX or OCT was demonstrable when using sera obtained from individuals with an isolated sIgE CHX or from healthy controls. Unlike CHX, ALX and OCT, PHMB turned out to be a direct MC activator via occupation of MRGPRX2. PHMB-reactive sIgEs were demonstrable in some patients with an isolated sIgE CHX but were unable to trigger PHMB-induced degranulation in MRGPRX2 knock-down MCs.
MCs constitute an attractive tool to explore cross-reactivity between structurally similar compounds. Along with the identification of safe alternatives for the individual patient, the pMAT can advance our insights in sIgE cross-reactivity patterns including assessment of molecules not yet approved for human use.

This article is protected by copyright. All rights reserved.