title: Suppression of megakaryocyte colony growth by plasma from foals infected with equine infectious anemia virus.
abstract: Foals infected with equine infectious anemia virus become thrombocytopenic 7 to 20 days after virus inoculation, and within a few days following the onset of detectable viremia. The thrombocytopenia is associated with suppression of platelet production. Possible mediators of suppression of thrombopoiesis include tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta), cytokines that are released during inflammation. To assess effects of plasma or serum from infected foals on megakaryocyte (MK) growth and maturation in vitro, equine low-density bone marrow cells were cultured for clonogenic and ploidy assays. Neutralizing antibodies to TNF-alpha and TGF-beta were added to cultures to determine the contribution of these cytokines to suppression of thrombopoiesis. Plasma from the immediately pre-thrombocytopenia (Pre-Tp) period significantly reduced MK colony numbers. This suppression was partially reversed upon antibody neutralization of plasma TNF-alpha, TGF-beta, or both. There were no differences in ploidy distribution of MK grown in the presence of preinfection serum compared with those grown in the presence of Pre-Tp serum. These results indicate that TNF-alpha and TGF-beta may contribute to suppression of MK proliferation and represent likely factors in the pathogenesis of thrombocytopenia.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Tornquist
authors.forename: T B
authors.initials: TB
authors.lastname: Crawford
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology; D004859:Equine Infectious Anemia / Q000097:blood* / Q000473:pathology; D005260:Female; D006410:Hematopoiesis / Q000187:drug effects*; D006734:Horse Diseases / Q000097:blood* / Q000821:virology; D006736:Horses; D004860:Infectious Anemia Virus, Equine; D008533:Megakaryocytes / Q000166:cytology*; D010949:Plasma; D010976:Platelet Count; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D011003:Ploidies
chemical_list: D010980:Platelet Membrane Glycoproteins