Dexamethasone-induced bovine T-lymphocyte suppression and the effect upon susceptibility to sheep scab mite (Acari:...

The synthetic glucocorticoid dexamethasone was used to suppress bovine T-lymphocyte function. Dexamethasone-treated animals were challenged with Psoroptes ovis (Hering) to determine if the immunosuppressive treatment would normalize susceptibility to infestation. Dexamethasone suppressed T-lymphocyte function and anti-P. ovis antibody production, and delayed the onset of scab lesions. All animals were not equally susceptible to infestation as a result of dexamethasone treatment. These data further support the importance of anti-P. ovis antibody in colonization of cattle by P. ovis and the pathology associated with scab mite infestation.