Transplant-acquired allergy in HCT-recipients: Reference for clinical management.

Transplant-acquired allergy (TAA) is well known in pediatric patients undergoing liver transplantation. Regarding allogeneic hematopoietic cell transplantation (allo-HCT), the clinical characteristics of TAA have not been fully elucidated. Clinical manifestations of TAA include eczematous dermatitis, allergic rhinitis, and asthma. It is known that allergic diseases are transferable from allergic donors to non-allergic recipients via allo-HCT. The potential mechanism is the transfer of allergen-specific memory B cells resulting in Th2-skewed allergy-specific immune responses. Retrospective studies have suggested that cord blood transplantation (CBT) and the immunosuppressant tacrolimus have a significant impact on the development of TAA. The reported prevalence varies according to study design, diagnostic methods, and study population, and the suspected allergens vary widely among individuals. Prospective cohort studies and further mechanistic investigations are warranted to provide robust evidence on the prevalence and risk factors associated with TAA.