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United States Department of Agriculture

Agricultural Research Service

Title: Lymphocyte Responses and Immunophenotypes in Horses with Sarcocystis Neurona Infection

Authors
item Tornquist, S - OREGON STATE UNIVERSITY
item Boeder, L - OREGON STATE UNIVERSITY
item Mattson, D - OREGON STATE UNIVERSITY
item Cebra, C - OREGON STATE UNIVERSITY
item Bildfell, R - OREGON STATE UNIVERSITY
item Hamir, Amirali

Submitted to: Equine Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 2001
Publication Date: November 1, 2001

Interpretive Summary: Infection of horses with a parasite (Sarcocystis neurona) of brain and spinal cord is relatively widespread based on the prevalence of serum antibodies, but development of associated clinical disease is much less common. The host immune response is likely to be an important factor in determining outcome of infection with this organism. In this study, immune responses to the parasite in serum-positive horses with neurologic disease were compared with those from serum-positive horses that did not have any neurologic signs. Immune cells (lymphocytes) in the blood of horses with neurologic signs had significantly lower responses to a laboratory test (Con A stimulation) than those from horses with no neurologic signs. Whether the difference in immune reactivity is a cause or effect of the parasitic infection is not known. In horses that do not develop the neurologic disease immune reactivity may be important in controlling the parasitic infection and damage to the central nervous system.

Technical Abstract: Infection of horses with Sarcocystis neurona (S. neurona) is relatively widespread based on the prevalence of serum antibodies, but development of associated clinical disease is much less common. The host immune response is likely to be an important factor in determining outcome of infection with this organism. In this study, cell-mediated immune responses to S. neurona in seropositive horses with neurologic disease were compared with those from seropositive horses that were asymptomatic. Lymphocytes from symptomatic horses had significantly lower proliferative responses to non-specific (Con A) stimulation and S. neurona antigen than those from asymptomatic horses. Asymptomatic horses had higher mean percentages of circulating CD4+ cells than symptomatic horses. Whether the difference in lymphocyte reactivity is a cause or effect of S. neurona infection is not known. The higher proportion of CD 4+ or T helper cells in horses that do not develop disease suggests that increased CD 4+ reactivity may be important in controlling S. neurona infection and damage to the central nervous system that can cause neurologic disease.

Last Modified: 12/20/2014
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