Blood T6-lymphocyte antigen levels as a poor resistance marker in ovine dermatophilosis.

Merino ewes lambs from a flock expected to have a high prevalence of dermatophilosis were examined for lesions at marking, weaning and prior to first shearing. Blood was collected at marking and prior to shearing to enable quantification of T6-lymphocyte antigen levels in peripheral blood mononuclear cells (PBM) using monoclonal antibody SBU-T6 20-27. A group of the lambs that had persistent and/or severe dermatophilosis had significantly lower (P < 0.05) mean levels of T6-lymphocyte staining in PBM than those with minimal or no dermatophilosis in blood samples collected prior to shearing. However, the wide variability of this parameter in resistant and susceptible lambs indicated that this would not be a satisfactory procedure to rank sheep for resistance to dermatophilosis.