Lymphocyte Count, ATG Dose and Incidence and Severity of GVHD in Pediatric Recipients of HSCT

Despite increasing success rate in hematopoietic stem cell transplantation (HSCT) control of graft versus host disease (GVHD) remains a significative burden in mortality and morbidity. A lot of strategies could lower the incidence and gravity of the disease and immunosuppressive treatment as GVHD prophylaxis still represent the main method.

Although immunosuppressive treatment showed a good effect on GVHD mortality a lot of studies also highlight an increase of relapse and infection related mortality that jeopardize the effect on overall survival of HSCT recipient. Using anti thymocyte globulin (ATG) as GVHD prophylaxis shares the same double-edge effect as other immunosuppressive treatment although is still unclear how manage dose and timing of the infusion to minimize promoting effect on infections and maximize protective effect on GVHD. Biological effect of ATG lead to a dose- related delay in all class of T-cell reconstitution but our data are mostly from adult studies with high doses between 30 and 60 mg/kg due to the more important burden of GVHD in HSCT adult population. As for other treatment in HSCT conditioning we would like to study a personalized approach for ATG treatment: some studies focus on tuning of ATG dose for kilos but previous evidence showed that the same dose could made too little or too much immunosuppressive effect for different patients, even though same age and same stem cell source.