Analysis of the antigen-specific IFN-gamma producing T-cell subsets in cattle experimentally infected with Mycobacterium bovis.

Abstract

Three 10 months old cattle were infected by the intratracheal route with 10(6)cfu of a field strain of Mycobacterium bovis. Blood samples were regularly collected for in vitro IFN-gamma production after antigenic stimulation. Peripheral blood cells of infected animals produced IFN-gamma in response to crude M. bovis antigens (live and heat-inactivated BCG and protein-purified derivative (PPD)) 3-4 weeks after infection. The ratio of the response to bovine PPD versus avian PPD indicated a specific sensitisation for M. bovis antigens. Three months post-infection (PI), animals were culled and M. bovis was cultured from tubercle lesions. At different time points, the frequency of specific M. bovis IFN-gamma producing CD4+, CD8+ and WC1+ T-cells in the peripheral blood was examined by flow cytometry. Two colour immunofluorescence staining of intracellular IFN-gamma and bovine cell surface molecules showed that both CD4+ and CD8+, but not WC1+, T-cells produced IFN-gamma following stimulation with PPD, live or killed BCG. In two animals analysed, the relative percentage of circulating IFN-gamma producing CD8+ cells decreased between week 5 and week 9 PI. The same evolution was not observed for IFN-gamma secreting CD4+ cells. Magnetic positive selection of T-cells from infected animals showed that CD4+ T-cells produced specific IFN-gamma only in the presence of antigen presenting cells (APCs). Positively selected CD8+ T-cells secreted IFN-gamma only in the presence of recombinant human IL-2 and APCs. In vitro depletion of the CD4+ T-cells, but not the depletion of CD8+ or WC1+ T-cells, resulted in abrogation of the specific IFN-gamma production showing the key role of this cell population for the specific IFN-gamma production.

• Authors: K Walravens, V Wellemans, V Weynants, F Boelaert, V deBergeyck, J-J Letesson, K Huygen, J Godfroid
• Journal: Veterinary immunology and immunopathology (Vet Immunol Immunopathol) Vol. 84 Issue 1-2 Pg. 29-41 (Jan 01 2002) ISSN: 0165-2427 [Print] Netherlands
• PMID: 11825596 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Interferon-gamma

Topics

• Animals
• CD4-Positive T-Lymphocytes (immunology)
• CD8-Positive T-Lymphocytes (immunology)
• Cattle
• Interferon-gamma (biosynthesis)
• Male
• T-Lymphocyte Subsets (immunology)
• Tuberculosis, Bovine (immunology)