D3.61 - Acquired Food Allergy After Allogeneic Hematopoietic Stem Cell Transplantation From a Non-Allergic Unrelated Donor

Introduction Allogeneic hematopoietic stem cell transplantation (HSCT) may rarely lead to the onset of food allergy. Understanding the pathogenesis is essential to improve patient management. We describe a case of de novo IgE-mediated food allergy occurring in an adult patient after HSCT from a donor with no history of food allergy. Informed consent was obtained.

Case presentation A 42 yo woman with a history of allergic rhinitis (AR) since 26 yo, sensitized to grass pollen and affected by oral allergy syndrome (OAS) to melon and watermelon, developed B-cell Philadalphia negative acute lymphoblastic leukemia at 38 yo. Two years after first line therapy she experienced central nervous system relapse, therefore she underwent salvage therapy and HSCT. She received peripheral stem cells from a fully matched unrelated donor (MUD), myeloablative condition was administered (total body irradiation,12Gy and fludarabine) and graft-versus-host disease prophylaxis included antithymocyte globulin, cyclosporine A and mycophenolate mofetil. Engraftment was prompt. Post-transplant complications included severe gastrointestinal mucositis, febrile neutropenia, CMV and HSV-2 reactivation. Six months after transplant, with full donor chimerism, mucositis resolved but the patient developed immediate reactions (lip and oral edema, pharyngeal pruritus and dyspepsia) following ingestion of partially cooked milk and egg-containing foods. She tolerated small amounts of heated milk and baked egg in a wheat matrix. The patient reported resolution of both OAS and AR.

Skin prick tests were positive for egg white (++++) , egg yolk (+++), α-lactalbumin (++), and timothy (+++),  histamine control (+++). Serological testing (kUA/L) showed: total IgE 296; specific IgE to egg white 6.63, egg yolk 3.38, Gal d 1 8.58, Gal d 2 2.02, milk 9.91, Bos d 4 12.30, casein and β-lactoglobulin negative, timothy 0.65, Phl p 1 0.90, Phl p 5b-Phl p 7-Phl p 12 negative. The diagnosis was α-lactalbumin allergy, requiring avoidance of raw or partially cooked milk, and egg allergy to ovomucoid and ovalbumin. Continued consumption of egg-containing foods baked within a wheat matrix in tolerated amounts was recommended, avoiding unprocessed egg.

Conclusions This case highlights that HSCT from a healthy MUD without food allergy history may lead to the development of IgE-mediated food allergy, with gastrointestinal barrier impairment representing a possible facilitating factor. Careful clinical monitoring in the post-transplant period is essential when symptoms related to specific food intake arise, with the goal of ensuring patient safety and preventing potentially hazardous exposures.