The uptake of respiratory syncytial virus (RSV) antigen by cattle dendritic cells was investigated. Pathways of antigen uptake were monitored by flow cytometry using specific tracers and by proliferation assays, which were used to measure the presentation of RSV antigen and ovalbumin. Inhibitors that differentially affected pathways were used to distinguish them. Presentation of RSV antigen, but not ovalbumin, was inhibited by phorbol myristate acetate and filipin, which have been reported to inhibit caveolae, but not by cytochalasin D, amiloride, or mannose. These inhibitors have been reported to block macropinocytosis and other actin-dependent uptake mechanisms, endocytic pathways involving clathrin-coated pits, and the mannose receptor. Furthermore, co-localization of RSV antigen and caveolae was observed by confocal microscopy. Thus, the major route for uptake of RSV antigen by cattle dendritic cells is one mediated by caveolae, adding a pathway of antigen uptake by dendritic cells to those established. J. Leukoc. Biol. 66: 50-58; 1999.

The potential effects of agricultural policy on the financial structure of farms is often not fully considered. Although it has been recognized that policies that reduce business risk may induce farmers to increase financial risk, the effects of income policies on farm leverage have not been investigated. This paper explores the relationship between farm policy and debt‐equity structure for a risk‐averse expected utility maximizer.

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؉ -depleted animals exhibited decreased antigen-specific lymphocyte proliferative response, an increased antigen-specific production of interleukin-4, and a lack of specific immunoglobulin G2 antibody. This suggests that WC1 ؉ ␥␦ TCR ؉ cells contribute, either directly or indirectly, toward the Th1 bias of the immune response in bovine tuberculosis-a hypothesis supported by the decreased innate production of IFN-␥, which was observed in WC1 ؉ -depleted calves.

An in vitro model system has been developed in which freshly isolated resting WC1+ gamma/delta TcR+ T cells proliferate in response to cells transformed by the protozoan parasite Theileria annulata, providing a strategy in which the basis of activation of naive gamma/delta T cells can be investigated. Irradiated parasite-transformed cells stimulate the proliferation, but not cytolytic activity, of autologous peripheral blood mononuclear cells (PBMC) from non-immune animals. The proliferating cells are mainly WC1+ gamma/delta T cells. The majority of WC1+ gamma/delta T cells in freshly isolated PBMC express CD25 at a low level that increases when stimulated with T. annulata-infected cells. Purified WC1+ gamma/delta T cells fail to proliferate when cultured with irradiated T. annulata-infected cells and produce a small proliferative response to IL-2, but proliferate strongly to irradiated or lightly fixed Theileria-infected cells in combination with IL-2. The Theileria-infected cells express cytokine transcripts encoding IL-1 alpha, IL-1 beta, IL-6 and IL-10, but not IFN gamma, IL-2, IL-4 and IL-7. Purified WC1+ gamma/delta T cells stimulated with T. annulata-infected cells with or without IL-2 fail to produce IL-2 transcripts, but do produce those for TNF alpha. These experiments show that WC1+ gamma/delta T cells recognize a surface determinant on T. annulata-infected cells, that together with a second signal, which can be provided by exogenous IL-2, stimulates their proliferation.

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Few data are available regarding the induction of memory T-lymphocyte responses in cattle following Bacille Calmette Guérin (BCG) vaccination. Studies of the immune response induced by BCG vaccination provide an insight into the basis of antimycobacterial immunity that could be exploited for the development of more effective vaccination strategies. We used autologous dendritic cells (DC) infected with Mycobacterium bovis Bacille Calmette Guérin (BCG) or pulsed with purified protein derivative from M. bovis (PPD-B) or M. avium (PPD-A) to assess responses of CD4+, CD8+ and WC1+ gammadelta TCR+ lymphocytes from BCG vaccinated and nonvaccinated cattle. Mycobacteria-specific CD4+ and CD8+, but not WC1+ gammadelta TCR+, memory T lymphocytes were demonstrated in BCG-vaccinated cattle. CD4+ and CD8+ lymphocytes proliferated and produced interferon (IFN)-gamma in response to BCG-infected or PPD-B-pulsed DC. Proliferative responses were greater for CD4+ than CD8+ lymphocytes, although secretion of IFN-gamma was higher from the CD8+ T cells. Responses to PPD-A-pulsed DC were lower, with no CD8+ response. Lymphocytes from nonvaccinated calves were also stimulated to proliferate by BCG-infected DC, although the magnitude of proliferation was lower. The findings suggest that immunity to M. bovis induced by BCG vaccination in cattle may involve CD8+ memory T cells which produce IFN-gamma, as well as CD4+ memory T cells.