Synergistic combinations of OX40L antibodies for the treatment of GvHD

A method of treating or preventing transplant rejection in a primate subject in need thereof, comprising:

• administering intravenously to the subject:
• a) at least one anti-OX40L antibody or fragment thereof that antagonizes specific binding of OX40 to OX40L;
• and
• b) at least one CTLA4-Fc;
• wherein the at least one anti-OX40L antibody or fragment thereof is intravenously administered at a dose of about 5 mg/kg to about 20 mg/kg on the day of transplant and at a dose of about 1 mg/kg to about 10 mg/kg at least once a week following the day of the transplant;
• and
• wherein the at least one CTLA4-Fc is intravenously administered at a dose of about 5 mg/kg to about 20 mg/kg on the day of transplant and at a dose of about 5 mg/kg to about 20 mg/kg at least bi-weekly following the day of the transplant.