An acid-modified arabinogalactan protein composition, having an arabinose-galactose ratio of less than 3.5:1 or less than 80% of the arabinose:galactose ratio of the arabinogalactan protein component of the composition prior to acid modification, prepared from Astragalus membranaceus, especially from the roots of Atragalus membranaceus, is capable of reconstitution into an aqueous intravenously injectable formulation; and is useful for stimulating hematopoiesis, inducing the proliferation or maturation of megakaryocytes, stimulating the production of IL-1beta, Il-6, TNF-alpha, IFN-gamma, GM-CSF, or G-CSF, stimulating the production or action of neutrophils, treating neutropenia, anemia, or thrombocytopenia, accelerating recovery from exposure (e.g. accidental or non-therapeutic exposure, as well as therapeutic exposure) to cytotoxic agents or radiation, treating cachexia, emesis, or drug withdrawal symptoms, or modifying biological responses or protecting hepatic cells in hepatitis B, in a mammal when intravenously administered to the mammal.