title: Streptococcus uberis-specific T cells are present in mammary gland secretions of cows and can be activated to kill S. uberis.
abstract: The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigen-presenting cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage of responding T cells were of the CD8(+) memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8(+) subset bearing memory cell markers (CD45A(-), CD45RO(+)), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for the prevention of mastitis caused by S. uberis.
authors.affiliation: AgResearch, Hopkirk Research Institute, Grasslands Reseach Centre, Tennent Drive, Private Bag 11008, Palmerston North, New Zealand.
authors.forename: Michel
authors.initials: M
authors.lastname: Denis
authors.forename: S Jane
authors.initials: SJ
authors.lastname: Lacy-Hulbert
authors.forename: Bryce M
authors.initials: BM
authors.lastname: Buddle
authors.forename: John H
authors.initials: JH
authors.lastname: Williamson
authors.forename: D Neil
authors.initials: DN
authors.lastname: Wedlock
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000382:microbiology; D002417:Cattle; D049109:Cell Proliferation; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008321:Mammary Glands, Animal / Q000276:immunology* / Q000378:metabolism*; D008414:Mastitis, Bovine / Q000097:blood / Q000276:immunology* / Q000382:microbiology* / Q000517:prevention & control; D013290:Streptococcal Infections / Q000097:blood / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D013291:Streptococcus / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial; D016753:Interleukin-10; D007371:Interferon-gamma