Teat canal keratin (n = 461) and mammary gland secretions (n = 370) were collected from 31 unbred and 85 primigravid Jersey heifers from one research and three commercial dairy herds. Of 97 heifers from which secretion samples were obtained, 96.9% had intramammary infections and 29% showed clinical symptoms. Seventy-five percent of quarters were infected. Staphylococcus aureus were isolated from 36 (37.1%) heifers and 55 (14.9%) quarters. One hundred and eight (93.1%) heifers and 326 (70.7%) quarters had teat canals colonized with mastitis pathogens. Staphylococcus aureus were isolated from teat canal keratin samples from 36 (31%) heifers and 57 (12.3%) quarters. The three most common species isolated from secretion and teat canal keratin samples were Staphylococcus chromogenes, Staphylococcus hyicus, and S. aureus. Secretions from infected (n = 240) and uninfected (n = 85) quarters had SCC of 13.6 X 10(6)/ml and 5.7 X 10(6)/ml. Macrophages were the most numerous cell type in secretions of infected and uninfected quarters. Quarters with teat canal colonization, but with no intramammary infections, exhibited higher SCC in secretion (9.3 X 10(6)/ml) than quarters without both teat canal colonizations and intramammary infections (4.9 X 10(6)/ml). Data indicated that intramammary infections and teat canal colonizations were more prevalent and SCC higher than previously realized in dairy heifers.

Immunization of hypercholesterolemic mice with selected apoB-100 peptide antigens reduces atherosclerosis but the precise immune mediators of athero-protection remain unclear. In this study we show that immunization of apoE (-/-) mice with p210, a 20 amino acid apoB-100 related peptide, reduced aortic atherosclerosis compared with PBS or adjuvant/carrier controls. Immunization with p210 activated CD8+ T cells, reduced dendritic cells (DC) at the site of immunization and within the plaque with an associated reduction in plaque macrophage immunoreactivity. Adoptive transfer of CD8+ T cells from p210 immunized mice recapitulated the athero-protective effect of p210 immunization in naïve, non-immunized mice. CD8+ T cells from p210 immunized mice developed a preferentially higher cytolytic response against p210-loaded dendritic cells in vitro. Although p210 immunization profoundly modulated DCs and cellular immune responses, it did not alter the efficacy of subsequent T cell dependent or independent immune response to other irrelevant antigens. Our data define, for the first time, a role for CD8+ T cells in mediating the athero-protective effects of apoB-100 related peptide immunization in apoE (-/-) mice.

Histologic observations of mammary tissue samples from unbred heifers revealed that secretory parenchyma from uninfected quarters was undeveloped, exhibiting small alveoli with a limited luminal area and a large interalveolar stromal area. Tissues from quarters infected with Staphylococcus aureus were less developed, exhibiting less alveolar epithelial and luminal areas and more interalveolar stroma compared with tissues from uninfected quarters. Such quarters also demonstrated minimal secretory activity. Macroscopic and microscopic abscesses were observed in one quarter with S. aureus intramammary infection. Staphylococcus aureus-infected quarters showed greater leukocyte infiltration into mammary parenchymal components and cistern lining compared with uninfected quarters. Quarters infected with non-aureus staphylococci also exhibited greater leukocyte infiltration and greater percentages of interalveolar stroma compared with uninfected controls. Results demonstrated that presence of infection increased leukocytosis into the mammary gland and reduced secretory activity in heifers, suggesting a deleterious effect on future milk production.

BackgroundThe lipid milleu exacerbates the inflammatory response in atherosclerosis but its effect on T cell mediated immune response has not been fully elucidated. We hypothesized that lipid lowering would modulate T cell mediated immune function.Methods and ResultsT cells isolated from human PBMC or splenic T cells from apoE-/- mouse had higher proliferative response to T cell receptor (TCR) ligation in medium supplemented with 10% fetal bovine serum (FBS) compared to medium with 10% delipidated FBS. The differences in proliferation were associated with changes in lipid rafts, cellular cholesterol content, IL-10 secretion and subsequent activation of signaling molecule activated by TCR ligation. Immune biomarkers were also assessed in vivo using male apoE-/- mice fed atherogenic diet (AD) starting at 7 weeks of age. At 25 weeks of age, a sub-group was switched to normal diet (ND) whereas the rest remained on AD until euthanasia at 29 weeks of age. Dietary change resulted in a lower circulating level of cholesterol, reduced plaque size and inflammatory phenotype of plaques. These changes were associated with reduced intracellular IL-10 and IL-12 expression in CD4+ and CD8+ T cells.ConclusionOur results show that lipid lowering reduces T cell proliferation and function, supporting the notion that lipid lowering modulates T cell function in vivo and in vitro.

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