Phenotyping of lymphocyte subsets in the vascular and epithelial lesions of a cow with malignant catarrhal fever.

Surface marker analysis of lymphoid cells infiltrating the vascular and epithelial lesions of a cow with malignant catarrhal fever (MCF) was conducted by immunohistochemistry using ten monoclonal antibodies. The majority of lymphoid cells in these lesions had BoCD8, BoCD6 or BoCD2, but they rarely possessed N-cell (BoCD5+/BoCD4-/BoCD8-, non-T non-B) markers. Similar reactivity was seen in lymphoid cells of perivascular infiltrates in the liver, heart and brain, and in T-dependent areas of lymph nodes. These results suggest involvement of cytotoxic T-lymphocytes in the pathogenesis of MCF.