Antithymocyte globulin dosing

Nonspecific immunosuppressive therapy in an adult patient is usually through cyclosporin (35), started intravenously at the time of transplantation, and given orally once feeding is tolerated. Typically, methylprednisone is started also at the time of transplantation, then reduced to a maintenance dose. A athioprine (31) may also be used in conjunction with the prednisone to achieve adequate immunosuppression. Whereas the objective of immunosuppression is to protect the transplant, general or excessive immunosuppression may lead to undesirable compHcations, eg, opportunistic infections and potential malignancies. These adverse effects could be avoided if selective immunosuppression could be achieved. Suspected rejection episodes are treated with intravenous corticosteroids. Steroid-resistant rejection may be treated with monoclonal antibodies (78,79) such as Muromonab-CD3, specific for the T3-receptor on human T-ceUs. Alternatively, antithymocyte globulin (ATG) may be used against both B- and T-ceUs. 

It has been postulated that early treatment with very high doses of intravenous A-acetylcysteine and the use of immunomodulatory drugs, such as antithymocyte globulin and ciclosporin, can improve the recovery of hematological parameters, even in the case of pancytopenia (37). One case of gold-induced aplastic anemia, unresponsive to various treatments, recovered after therapy with antithymocyte globulin (SED-12, 522). 

Many different types of immunosuppressants can be used to prevent or control rejection. Most of them, including steroids, suppress the entire immune system (Merck 2003). Antilymphocyte globulin, antithymocyte globulin, and monoclonal antibodies suppress only specific parts of the immune system. Immunosuppressants must be taken for an indefinite period. High doses are usually necessary for the first few weeks, and after that smaller doses can usually prevent rejection (Stark et al. 2002 Villard 2006). 

When detected by biopsy, rejection is treated aggressively by increasing the level of immunosuppression and the dose of corticosteroids (Winkel et al. 1999). In severe cases, additional agents such as antithymocyte globulin, OKT3, cyclophosphamide, methotrexate, vincristine, tacrolimus, rapamycin, or mycophenolate mofetil maybe required (Knisely... 

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