Method for prevention of graft versus host disease

A method for prevention of or prophylaxis against GVHD in a patient to undergo a bone marrow transplant where bone marrow of a donor has been matched to the patient for HLA compatibility comprising the steps of treating the bone marrow of the donor with a monoclonal antibody produced by the hybridoma deposited as ATCC HB 9918 and complement in an amount sufficient to deplete T cytotoxic/suppressor cells to less than 1% of pretreatment levels, transplanting the treated bone marrow to said patient, and administering to said patient an effective amount of Cycloporine A sufficient to inactivate CD4.sup.+ cells.