Newly acquired kiwi fruit allergy after bone marrow transplantation from a kiwi‐allergic donor

Abstract Background The phenomenon of allergy transfer from an allergic donor to a non‐allergic recipient via hematopoietic cell transplantation has been described by several reports. However, it could not yet been conclusively shown that allergic reaction of the recipient is elicited by the donor's cells. Objectives In the case of a 46‐year‐old male patient who – for the first time in his life – had two episodes of oral allergic syndrome upon kiwi consumption after having received myeloablative hematopoietic stem cell transplantation (HCT) from his kiwi‐allergic sister, we aimed to clarify the origin of allergen reactive cells in the donor. We not only intended to demonstrate if allergy was transferred by HCT but also to present an experimental workup for the analysis of allergy transfer by HCT. Methods Allergic sensitization to kiwi in recipient and donor was proven by ImmunoCAP. Furthermore, origin of peripheral blood mononuclear cells (PBMCs) was analyzed by chromosomal fluorescence in situ hybridization (FISH). To confirm allergic reaction and activation of hematopoietic cells by customized kiwi extract, we performed basophil activation test from whole blood as well as T cell proliferation assays from purified PBMCs of both recipient and donor. Results Basophil activation upon kiwi extract was demonstrated in both recipient and donor. Besides, we showed proliferation of CD4 + T cells after incubation with kiwi extract. FISH analysis proved that hematopoietic cells of the male recipient completely originated from the female donor. Conclusion Exemplified in this patient, we show for the first time that allergy transfer is mediated by the donor's cells. Moreover, our experimental approach using customized kiwi extract to prove contribution of kiwi‐specific T and B cells in both kiwi‐allergic recipient and donor could serve as a model approach for future studies.