Characteristics and management of hypersensitivity reactions with rabbit anti-thymocyte globulin in pediatric patients.

Background: Anti-thymocyte globulin (ATG) has been successfully used for decades to prevent graft versus host disease before hematopoietic stem cell transplantation (HSCT) as a part of conditioning regimen. However, sometimes hypersensitivity reactions may limit its use. Objective: To evaluate hypersensitivity reactions experienced during rabbit-ATG infusion among children and present successful desensitization protocol. Methods: The medical records of pediatric patients who were given rabbit-ATG treatment at our tertiary center hospital HSCT unit between 2019 and 2022 were reviewed retrospectively. Diagnosis of the patients, age at the time of HSCT, gender, presence of hypersensitivity reaction to rabbit-ATG, and management were evaluated. Characteristics of the reaction and presence of hypersensitivity reaction to other drugs were also noted. If performed, desensitization protocols were evaluated retrospectively. Results: We evaluated 81 patients; 66.6% of them (n = 54) were boys. The mean age of the patients was 8.78 ± 5.48 years. Hypersensitivity to rabbit-ATG was seen in six patients (7.4%). Four of them (4.9%) had anaphylaxis; two (2.4%) had urticaria. Intradermal test performed to every patient before the first dose of ATG infusion was detected a positive result in 1 patient (1.2%) . None of these seven patients had allergic reactions to other drugs before. Successful ATG desensitization was performed in five patients by using a 12-16 step protocol due to patients' reaction severity. Conclusion: This study aimed to evaluate hypersensitivity reactions with rabbit-ATG in children. A successful desensitization protocol with rabbit-ATG is presented. Desensitization must be performed with an experienced team very carefully in the absence of alternative drug.