Antibodies to anti-thymocyte globulin in aplastic anemia patients have a negative impact on hematopoietic SCT

Severe aplastic anemia (SAA) is a life threatening BM failure and the preferred therapy for children is allogeneic hematopoietic SCT (HSCT) with an HLA-matched sibling donor. Immunosuppressive therapy with anti-thymocyte globulin (ATG) and CsA is an alternative for patients lacking an HLA-identical donor. For many years, horse ATG (hATG) was the preferred source, but in Europe the production of hATG ended in 2007, and hATG was replaced by rabbit ATG (rATG). Recently, Scheinberg et al. published a randomized trial comparing rATG with hATG in SAA patients and concluded that hematological response and survival using hATG was superior to rATG. Here, we report in a pediatric SAA transplant cohort that the use of rATG as first-line therapy, followed by rATG in the HSCT conditioning regimen, can result in severe transplant-related problems. Sensitization toward ATG, defined as production of anti-ATG Abs, has been observed in SAA patients as well as in solid organ and HSCT recipients. When a second immunosuppressive course is required or in vivo T-cell depletion is needed in the context of HSCT, a switch from hATG to rATG is advisable to lower the risk of adverse reactions due to the potential presence of anti-hATG Abs (read more).

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