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  • Author or Editor: Douglas E. Jones x
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Objective—To characterize the early cellular immune response to Mycobacterium avium subsp paratuberculosis ( MAP) infection and evaluate the development of granulomatous inflammation at the SC injection site in experimentally inoculated calves.

Animals—Forty-eight 4-week-old calves.

Procedure—Calves received an SC injection of MAP strain 19698 (n = 25), sterile saline (0.9% NaCl) solution (20), or a commercial paratuberculosis vaccine (3); the inoculation site tissue and associated draining lymph node were excised at postinoculation day (PID) 0 (n = 36), 7 (14), 14 (6), 21 (8), and 60 (32). Sections of inoculation site tissues were evaluated immunohistochemically for T-cell subsets; lymph node mononuclear cells (LNMCs) were assessed for T-cell surface markers and for intracellular interferon-γ via flow cytometry.

Results—At MAP inoculation sites, calves developed mild, focal granulomatous inflammation by PID 7; by PID 60, areas of inflammation contained macrophages with numerous lymphocytes. Compared with control calves, there was increased antigen-specific LNMC proliferation in MAP- and vaccine- inoculated calves at PID 60, although proliferation among lymphocyte subsets was not significantly different between MAP-inoculated and control calves; in vaccine-inoculated calves, CD4+ T-cells predominated. In MAP-inoculated and control calves, antigenspecific interferon-γ production by LNMCs did not differ significantly; vaccine-inoculated calves had marked interferon-γ expression by CD4+ T-cells.

Conclusions and Clinical Relevance—In calves, SC administration of MAP resulted in granulomatous inflammation at inoculation sites and an antigen-specific T-cell proliferative response. Results suggest that this experimental system can be used to reproducibly generate antigen-specific T-cells during MAP infection for functional analysis. (Am J Vet Res 2005;66:474–482)

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in American Journal of Veterinary Research


Objective—To measure epithelial cell percentages and somatic cell counts (SCCs) in milk and determine whether isoflupredone acetate reduces mammary gland epithelial cell sloughing in cows with acute endotoxin-induced mastitis.

Animals—13 lactating Holstein cows.

Procedures—Determination of SCC and flow cytometric analysis of cytokeratin-positive (epithelial) cells in milk were performed before and 12 hours after induction of mastitis via intramammary administration of bacterial endotoxin in 8 cows and at the same time points in 5 cows without mastitis. Endotoxin-treated cows received isoflupredone acetate (20 mg) or saline (0.9% NaCl) solution (n = 4/group) IV after signs of mastitis developed.

Results—At the 12-hour time point, mean ± SD percentage of epithelial cells in milk increased from 2.74 ± 1.93% to 42.11 ± 36.21% and decreased from 5.73 ± 4.52% to 5.31 ± 1.93% in milk from cows with and without mastitis, respectively. Median (range) SCC in milk increased from 195,000 cells/mL (17,000 to 442,000 cells/mL) to 5,437,500 cells/mL (69,000 to 11,036,000 cells/mL) and from 19,000 cells/mL (9,000 to 125,000 cells/mL) to 51,000 cells/mL (10,000 to 835,000 cells/mL) in cows with and without mastitis, respectively. Changes in these variables were significantly greater in mastitis-affected cows. Administration of isoflupredone acetate did not affect epithelial cell percentage or SCC in milk.

Conclusions and Clinical Relevance—During the early phase of endotoxin-induced mastitis in dairy cows, large numbers of epithelial cells were sloughed into the milk. Epithelial cell damage likely precedes an influx of immune cells into affected mammary glands and may contribute to breakdown of the blood-milk barrier.

Full access
in American Journal of Veterinary Research



To determine whether clinical progression of paratuberculosis in cattle was associated with alterations in cytokine gene expression in affected tissues.


5 uninfected adult Holstein cows, 7 adult Holstein cows naturally infected with Mycobacterium paratuberculosis that did not have clinical signs of disease, and 4 adult Holstein cows naturally infected with M paratuberculosis that had progressive clinical signs of infection.


Samples of ileum and cecal lymph nodes were obtained from each animal at the time of slaughter. A reverse transcriptase-competitive polymerase chain reaction assay was used to determine mRNA expression of interferon-γ (IFN-γ) and interleukin 4 in each sample.


Interferon-γ gene expression was significantly higher in ileum and cecal lymph node samples from subclinically infected cows than from clinically infected cows.

Conclusions and Clinical Relevance

Progression of paratuberculosis to clinical stages is associated with reduced expression of IFN-γ at site of infection. If immune response to M paratuberculosis can be manipulated so that IFN-γ expression is increased, resistance to infection in cattle might be enhanced. (Am J Vet Res 1998;59:842–847)

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in American Journal of Veterinary Research