Immune response to Sarcocystis neurona infection in naturally infected horses with equine protozoal myeloencephalitis.
Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinically normal horses and 22 horses with EPM, diagnosed by the presence of S. neurona specific antibodies in the serum and/or cerebrospinal (CSF) and clinical signs, were evaluated for differences in the immune cell subsets and function. Our results demonstrated that naturally infected horses had significantly (P<0.05) higher percentages of CD4 T-lymphocytes and neutrophils (PMN) in separated peripheral blood leukocytes than clinically normal horses. Leukocytes from naturally infected EPM horses had significantly lower proliferation responses, as measured by thymidine incorporation, to a non-antigen specific mitogen than did clinically normal horses (P<0.05). Currently, studies are in progress to determine the role of CD4 T cells in disease and protection against S. neurona in horses, as well as to determine the mechanism associated with suppressed in vitro proliferation responses. Finally, overnight storage of blood samples appears to alter T lymphocyte phenotypes and viability among leukocytes.
Department of Large Animal Clinical Sciences, Phase II, Duck Pond Dr., Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, 24061, USA.
Jibing
J
Yang
Siobhan
S
Ellison
Robert
R
Gogal
Heather
H
Norton
David S
DS
Lindsay
Frank
F
Andrews
Daniel
D
Ward
Sharon
S
Witonsky
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000134:cerebrospinal fluid; D018791:CD4 Lymphocyte Count / Q000662:veterinary; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D004679:Encephalomyelitis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D006734:Horse Diseases / Q000276:immunology* / Q000469:parasitology; D006736:Horses; D007553:Isotope Labeling / Q000662:veterinary; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008934:Mitogens / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology; D012522:Sarcocystis / Q000276:immunology*; D012523:Sarcocystosis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D014316:Tritium
D000913:Antibodies, Protozoan; D008934:Mitogens; D014316:Tritium