Neutralization of interleukin-10 from CD14(+) monocytes enhances gamma interferon production in peripheral blood mononuclear cells from Mycobacterium avium subsp. paratuberculosis-infected goats.
The gamma interferon assay is used to identify Mycobacterium avium subsp. paratuberculosis-infected animals. It has been suggested that regulatory mechanisms could influence the sensitivity of the test when it is performed with cells from cattle and that the neutralization of interleukin-10 (IL-10) in vitro would increase the gamma interferon responses. To investigate the regulatory mechanisms affecting the gamma interferon assay with cells from goats, blood was collected from M. avium subsp. paratuberculosis-infected, M. avium subsp. paratuberculosis-exposed, and noninfected goats. Neutralization of IL-10 by a monoclonal antibody resulted in increased levels of gamma interferon production in M. avium subsp. paratuberculosis purified protein derivative (PPDj)-stimulated samples from both infected and exposed goats. However, the levels of gamma interferon release were also increased in unstimulated cells and in PPDj-stimulated cells from some noninfected animals following neutralization. Depletion of putative regulatory CD25(high) T cells had no clear effect on the number of gamma-interferon-producing cells. The IL-10-producing cells were identified to be mainly CD14(+) major histocompatibility complex class II-positive monocytes in both PPDj-stimulated and control cultures and not regulatory T cells. However, possible regulatory CD4(+) CD25(+) T cells produced IL-10 in response to concanavalin A stimulation. The numbers of CD4(+), CD8(+), and CD8(+) gammadelta T-cell receptor-positive cells producing gamma interferon increased following IL-10 neutralization. These results provide insight into the source and the role of IL-10 in gamma interferon assays with cells from goats and suggest that IL-10 from monocytes can regulate both innate and adaptive gamma interferon production from several cell types. Although IL-10 neutralization increased the sensitivity of the gamma interferon assay, the specificity of the test could be compromised.
Department of Animal Health, National Veterinary Institute, Oslo, Norway. kari.lybeck@vetinst.no
Kari R
KR
Lybeck
Anne K
AK
Storset
Ingrid
I
Olsen
D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D015511:Goat Diseases / Q000276:immunology*; D006041:Goats; D007371:Interferon-gamma / Q000378:metabolism*; D016753:Interleukin-10 / Q000037:antagonists & inhibitors*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000276:immunology; D009000:Monocytes / Q000276:immunology*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology*; D010283:Paratuberculosis / Q000276:immunology*
D015703:Antigens, CD; D016753:Interleukin-10; D007371:Interferon-gamma