Production of tumour necrosis factor alpha during bovine trypanosomiasis: possible correlation with severity of anaemia associated with the disease

This paper determines whether tumour necrosis factor (TNF alpha) (a cytokine that is predominantly secreted by cells of the monocyte/macrophage lineage) production is induced during bovine trypanosomiasis and wheather or not production is correlated with disease. TNF alpha titres in plasma from Boran cattle infected with T. vivax by tsetse fly transmission and of monocytes are illustrated. Data is also presented for TNF alpha mRNA expression in monocytes isolated from Trypanosoma vivax and T. Congolense infected cattle

Cloning of two members of the TNF - superfamily in cattle: CD40 ligand and tumor necrosis factor alpha

According to studies in human and mouse species it is apparent that both CD40 ligand and tumor necrosis factor alpha (TNF alpha) are members of a novel family of cytokines, referred to as the TNF - superfamily. This article reports the cloning of the cattle CD40 lignad and cattle TNF alpha, and shows the similarities between these molecules

Development of bovine-specific cytokine reagents at ILRAD

Infection of livestock with African trypanosomes leads to haematological changes such as anaemia and pancytopenia and to immune defects, including suppression of T-cell responsiveness and an excessive increase in the CD5+ B-cell population in blood and spleen. It has been shown that certain breeds of cattle have evolved mechanisms to reduce the effects of trypanosome infections. At ILRAD, trypanosome-specific immune responses of trypanotolerant N'Dama cattle (Bos taurus) are being compared with those of trypanosusceptible Boran (Bos indicus) cattle. The molecular and cellular basis of trypanotolerance are poorly defined, but preliminary data suggest that differences exist between these breeds at the level of T- and B-cell responses to trypanosome antigens during infection. Clear differences have been reported between N'Dama and Boran cattle in the quantity, quality and specificity of antibodies produced following trypanosome infection. Further characterization of these differences and evaluation of their role in trypanotolerance will require the availability of reagents for the analysis of bovine cytokine responses

Summary of discussion

ILRAD outlined two different areas of research concern to the trypanosomiasis program. One goal was to identify trypanosomal antigens responsible for the immunopathogenesis of the disease by determining how the infection of cattle with trypanosomes affects their immune system. A second goal was to identify protective immune responses that might be targeted at the parasite itself or at the mechanisms through which it causes disease

Bovine gamma delta T cell responses to the intracellular protozoan parasite Theileria parva

T cells bearing the gamma delta antigen receptor (gamma delta T cells) can constitute up to 50 percent of T cells in the peripheral blood and lymphoid organs of young cattle. We present data showing that gamma delta T cells are involved in immune responses against Theileria parva. Gamma delta T cells isolated from peripheral blood mononuclear cells (PBMC) of T. parva-naive and -immune cattle proliferated in the presence of fixed or unfixed autologous T. parva-infected lymphoblasts (TpL) and heat-stressed concanavalin A (ConA)-induced blasts (ConA blasts) but not untreated ConA blasts. The specificity of response was further evaluated with a panel of gamma delta T-cell receptor, but not by MAbs specific for class I and class II major histocompatibility complex (MHC) molecules. In addition, TpL but not ConA blasts from a variety of MHC-mismatched animals induced proliferation of the gamma delta T-cell lines and clones. these gamma delta T cells were found to respond to TpL infected with several different parasite stocks and failed to recognize TpL after elimination of the parasite by the theilericidal drug BW 720C. Assays for cytotoxic activity of gamma delta T cells sorted from bulk cultures of immune PBMC restimulated several times with autologous TpL demonstrated that effector cells whose specificity is similar to that of proliferating cells are generated. These results suggest that bovine gamma delta T cells are activated by and lyse T. parva-infected cells by recognizing conserved parasite-induced or parasite-derived antigens in an MHC-unrestricted fashion