Identification and characterization of monoclonal antibodies reactive with bovine, caprine and ovine T-lymphocyte determinants by flow microfluorimetry.

Comparative flow microfluorimetric (FMF) analysis was used to identify and characterize 27 monoclonal antibodies (MoAbs) reactive with bovine T-lymphocytes. Determinants present on all circulating T-lymphocytes were recognized by 11 MoAbs, 8 of which blocked E rosette formation. Determinants present on only the BoCD4+ T-lymphocyte subset were detected by 9 MoAbs, while determinants restricted to the BoCD8+ T-lymphocyte subset were recognized by 7 MoAbs. Competitive labeling experiments demonstrated that determinants recognized by subset-specific MoAbs were present on BoCD4 or BoCD8 molecules. Comparative studies revealed that some determinants, both pan-T specific and subset-specific, were conserved on homologous (orthologous) molecules expressed on leukocytes from other species of ruminants. Polymorphism was evident with several determinants.