This composition and method provides for a method for reducing GVHD in a human subject which comprises administering to the subject at a predefined interval effective GVHD-reducing doses of (a) a humanized antibody designated PRO 140, or of (b) an anti-CCR5 receptor monoclonal antibody. This invention also provides a method for inhibiting in a human subject the onset or progression of GVHD. This invention also provides a method for treating a subject with GVHD comprising administering to the subject (a) a monoclonal antibody which (i) binds to a CCR5 receptor on the surface of the subject's CD4.sup.+ cells, and (b) a non-antibody CCR5 receptor antagonist, in amounts effective to treat the subject.
