BOVINE-MILK LYMPHOCYTES DISPLAY THE PHENOTYPE OF MEMORY T-CELLS AND ARE PREDOMINANTLY CD8+

The phenotype of bovine milk lymphocytes was investigated and compared to peripheral blood lymphocytes using monoclonal antibodies specific for bovine leukocyte differentiation antigens and flow cytometry. T Ly mphocytes traffic selectively into bovine milk while B lymphocytes rep resent a minor population in milk by comparison to peripheral brood. T he vast majority of T cells in milk express alpha beta T cell receptor s and are predominantly CD8(+). T cells in milk express twofold higher levels of CD2 and fivefold lower levels of CD45R, characteristics ass ociated with memory T cells. Grouping of cows by lactational stage and analysis of lymphocyte subpopulation percentages indicated that CD4() T cells are present in relatively low numbers in milk of cows in the first 50 days of lactation and have a significant tendency to increas e in number as lactation progresses. (C) 1994 Academic Press,Inc.