CD40LG and Thrombocytopenia: Initial experience with heterotopic heart transplantation in the hCD39, hCRP, and hTBM multitransgene GTKO pig-to-baboon model indicates that in the presence of CVF and anti-CD154 mAb therapy, high level expression of hCD39 by the porcine vasculature is associated with less thrombocytopenia and better maintenance of plasma fibrinogen levels in recipient baboons (B. Ekser, unpublished observation).