Background and importance Rabbit antithymocyte immunoglobulin (ATG) is used to prevent or treat graft versus host disease (GVHD). There have been few studies on tolerance to administration of ATG in paediatric patients. It is related to immunomodulatory manifestations that cause an inflammatory response capable of triggering clinical and analytic manifestations similar to those of an infection, resulting in the administration of antibiotic in most patients.

Aim and objectives To describe the tolerance to administration of ATG in paediatric patients who underwent bone marrow transplantation (BMT) and to analyse its relationship with clinical and analytic manifestations similar to an infection.

Material and methods This was an observational retrospective study involving paediatric patients with BMT that received ATG (December 2010–February 2019). Variables collected were demographics (age/sex), BMT related variables (pathology, sources of haematopoietic stem cells (HSC), donor type), clinical symptoms (fever (secondary to ATG if 0–72 hours post-infusion), temperature), treatment (dose, premedication, side effects), analytics (maximum procalcitonin (PCT) and C reactive protein (CRP), liver and kidney function markers) and blood cultures. Variables were obtained from electronic/paper medical records and the oncohaematologic electronic prescribing programme.

Results Fifty-six patients were enrolled, 55.35% (31) men, with a median age of 7 years, and 92.8% (52) received ATG as prophylaxis and 7.2% (4) as refractory treatment of GVHD. The doses recorded were 1.25–2.5 mg/kg, with 2 mg/kg the most common dose (85.7%; 48) over 3 days (2 days if haploidentical BMT). All patients received premedication, full dose and no reduction in the rate of administration or discontinuation. The most frequent underlying diseases were oncological, mainly acute lymphoblastic leukaemia (57.1%; 32), and haematological (9 patients), mainly medullary aplasia (33.3%; 3). The main source of HSC was peripheral blood (50%; 28) and donor type was mismatched unrelated donor (39.28%; 22).

In 73.2% (41) of patients, fever (38.5°C±0.5) appeared 11.28 hours after the start of infusion and lasted 1.77±0.84 days; 82.9% (34) of these patients received broad spectrum antibiotic treatment (mostly cefepime, amikacin, teicoplanin) over 7.61±3.79 days, with positive blood culture in 7.3% (3). Markers of infection were altered in most patients, with average values for CRP of 97.55±59.45 mg/dL and PCT of 35.57±28.55 ng/dL.

Other side effects were hypertransaminasaemia (33.92%; 19), hyperbilirubinaemia (5.36%; 3), anaphylaxis (5.36%), capillary permeability syndrome (5.36%), alteration of renal function (1.78%; 1) and rash (1.78%).

Conclusion and relevance ATG treatment in paediatric patients was associated with mild side effects. ATG triggered analytical and clinically altered parameters that simulated infection and hence empirical antibiotherapy was initiated which could be stopped precociously in the event of toxic fever by ATG.

References and/or acknowledgements No conflict of interest.