T-CELL POPULATIONS AND CYTOKINE EXPRESSION IN MILK-DERIVED FROM NORMAL AND BACTERIA-INFECTED BOVINE MAMMARY-GLANDS

This study investigated the effect of naturally acquired bacterial inf ection of the bovine mammary gland on subpopulations of T lymphocytes and cytokine expression in milk. Twenty-nine lactating cows with masti tis were compared to 12 normal animals. CD4(+) lymphocytes represented a significantly greater percentage of the milk-derived lymphocytes in infected mammary glands compared to normal controls. Cytokine mRNA ex pression by cells derived from milk was investigated using reverse tra nscriptase-polymerase chain reaction (RT-PCR). No IL-2 or IL-4 mRNA wa s detected in any samples, while IFN-gamma mRNA was detected in all mi lk samples. IL-10 mRNA was detected in cells from the milk of 2 mastit ic cows and 1 normal cow, and IL-12 mRNA was detected in 2 cows with m astitis. While TNF-alpha mRNA was not detected in this study, IL-6 mRN A was identified in cells from the milk of all animals, with levels be ing greater in mastitic animals. (C) 1997 Academic Press.