Abstract: A pharmaceutical composition for use in preventing or treating graft versus host disease (GVHD) in a subject wherein the composition includes intact microvesicles isolated from a biological fluid using polyethylene glycol (PEG) precipitation, wherein administration of the pharmaceutical composition alleviates or prevents one or more symptoms of GVHD in the subject. Also described is a method of preventing or treating graft versus host disease (GVHD) in a subject comprising administering to the subject a pharmaceutical composition comprising intact microvesicles isolated from a biological fluid of an unrelated or related donor using polyethylene glycol (PEG) precipitation wherein one or more symptoms of GVHD comprising weight loss, cutaneous tissue damage, subcutaneous tissue damage, cutaneous inflammation, satellite cell necrosis, truncated lifespan, and/or subcutaneous inflammation are prevented or alleviated in the subject.