Inhibition of bovine peripheral blood mononuclear cell blastogenesis by fractionated mammary secretion

1. Bovine mammary secretion whey obtained during late involution markedly inhibited mitogen-induced blood mononuclear cell blastogenesis. 2. Whey proteins eluting in the first and second absorbance peaks following molecular exclusion chromatography were associated with greatest inhibition of mononuclear cell blastogenesis. 3. Greatest inhibition of concanavalin A-stimulated mononuclear cell blastogenesis was associated with high concentrations of whey proteins in absorbance peak 1. 4. Whole mammary secretion whey and whey proteins in absorbance peak 2 caused similar inhibition of concanavalin A- and phytohaemagglutinin-treated mononuclear cells. 5. Differential inhibition of mitogen-induced blastogenesis may reflect the presence of immunosuppressive substances in bovine mammary secretion whey which differ in specificity for bovine T-cell subsets.