A monoclonal antibody that identifies mature T lymphocytes of cattle.

Hybridomas to bovine leukocytes were produced by immunization of BALB/C mice with bovine lymphoblasts and fusion of the mouse spleen cells with mouse myeloma cells. Monoclonal antibodies (MABs) were tested against various cell populations by indirect fluorescent microscopy using fluorochrome conjugated antibodies to mouse immunoglobulins. MAB-15, one of the resulting MABs obtained after cloning antibody-producing hybridomas, reacted with 56.8 +/- 8.4% of peripheral blood mononuclear cells (PBMC). MAB-15 did not react with monocytes or B cells, but did react with T cells (fluorescein isothiocyanate-conjugated peanut agglutinin positive cells). MAB-15 reacted with 3.2% of thymocytes from adult cattle. In addition to reacting with T cells, MAB-15 reacted with neutrophils and eosinophils. MAB-15 was characterized as an IgM antibody that was unable to lyse PBMC in the presence of complement. Thus, MAB-15 is a useful marker of mature T cells in the mononuclear cell population.