Suppression of Megakaryocyte Colony Growth by Plasma From Foals Infected With Equine Infectious Anemia Virus
Susan J. Tornquist and
Timothy B. Crawford
From the Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA.
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-
(TNF-) and transforming growth factor-
(TGF-), 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- and TGF- 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-, TGF-, 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- and TGF- may contribute to suppression of MK proliferation and represent likely factors in the pathogenesis of thrombocytopenia.
Blood, Vol. 90 No. 6 (September 15), 1997:
pp. 2357-2363
© 1997 by The American Society of Hematology.
