BTK and anaphylaxis: Furthermore, inhibition of FcεRI-mediated signaling using Bruton Tyrosin Kinase (BTK) inhibitors, significantly reduced degranulation and cytokine production in human MCs and basophils, decreased bronchoconstriction in isolated human bronchi, and proved effective in preventing anaphylaxis in a passive systemic anaphylaxis model using humanized mice (170, 188) (Table 3).