title: The polysaccharide, PGG-glucan, enhances human myelopoiesis by direct action independent of and additive to early-acting cytokines.
abstract: beta-Glucans stimulate leukocyte anti-infective activity, enhance murine hematopoietic recovery following bone marrow injury and mobilize murine progenitor cells from bone marrow. This study evaluated the in vitro hematopoietic potential of the beta-glucan, PGG-glucan, on human bone marrow mononuclear cells (BMMC) and CD34+ BMMC compared with protein cytokines. In the presence of submaximal concentrations of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF; 0.5 ng/ml), PGG-glucan significantly increased BMMC myeloid colony formation comparable to the increase observed with either interleukin-3 (rhIL-3) or stem cell factor (rhSCF). Moreover, the addition of PGG-glucan to cultures containing GM-CSF + IL-3 or GM-CSF + SCF significantly augmented granulocyte-macrophage colony production above baseline, demonstrating that PGG-glucan acts independently of those early-acting cytokines and can enhance their activity in an additive manner. Anti-PGG-glucan monoclonal antibody specifically abrogated the growth-enhancing effect of added PGG-glucan in a saturable manner and other control carbohydrate polymers failed to affect colony formation. Further, PGG-glucan was not associated with induction of IL-6, GM-CSF production and removal of accessory cells by CD34+ cell isolation did not alter the PGG-glucan effect. These data demonstrate that PGG-glucan acts on committed myeloid progenitors to enhance human hematopoietic activity by a mechanism of direct action independent of IL-3 or SCF and independent of secondary cytokine stimulation.
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Turnbull
authors.forename: M L
authors.initials: ML
authors.lastname: Patchen
authors.forename: D T
authors.initials: DT
authors.lastname: Scadden
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001854:Bone Marrow Cells / Q000187:drug effects; D016207:Cytokines / Q000494:pharmacology*; D005936:Glucans / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D019891:Leukopoiesis / Q000187:drug effects*; D011994:Recombinant Proteins / Q000494:pharmacology; D019089:Stem Cell Factor / Q000494:pharmacology; D013268:Stimulation, Chemical; D047071:beta-Glucans
chemical_list: D000890:Anti-Infective Agents; D016207:Cytokines; D005936:Glucans; D007377:Interleukin-3; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D047071:beta-Glucans; C069894:poly-1-6-glucopyranosyl-1-3-glucopyranose glucan; D016178:Granulocyte-Macrophage Colony-Stimulating Factor