“…3 Interestingly, there are also reports on the occurrence of immediate-type allergic reactions to common allergens after organ transplantation in patients with no known allergy before transplantation. [4][5][6][7][8][9][10][11][12][13] Hypotheses on the pathogenesis are diverse; for example, for liver transplantation, adoptive transfer of immunoglobulin E (IgE) antibody-loaded mast cells in the vascular pool of the allograft from allergic donors 9,11,13 and an allergy-promoting effect of distinct immunosuppressors (namely, the calcineurin inhibitor tacrolimus) have been discussed. 4,8,10,14,15 Because the immunosuppressive drugs used to prevent allograft rejection (steroids, calcineurin inhibitors, and proliferation inhibitors) strongly suppress the cellular immune system, in particular T and B lymphocytes, 16 which play a key role in IgE-mediated immediate-type allergic reactions as well, 17 it was expected that transplant recipients would not develop sensitizations or, at least, no clinical signs of allergy.…”