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In mammals, the inducible cytokine interleukin 10 is a feedback negative regulator of inflammation. To determine the extent to which this function is conserved in birds, recombinant chicken IL-10 was expressed as a secreted human Ig Fc fusion protein (chIL-10-Fc) and used to immunise mice. Five monoclonal antibodies (mAb) which specifically recognise chicken IL-10 were generated and characterised. Two capture ELISA assays were developed which detected native chIL-10 secreted from chicken bone marrow-derived macrophages (chBMMs) stimulated with lipopolysaccharide (LPS). Three of the mAbs detected intracellular IL-10. This was detected in only a subset of the same LPS-stimulated chBMMs. The ELISA assay also detected massive increases in circulating IL-10 in chickens challenged with the coccidial parasite, Eimeria tenella. The same mAbs neutralised the bioactivity of recombinant chIL-10. The role of IL-10 in feedback control was tested in vitro. The neutralising antibodies prevented IL-10-induced inhibition of IFN-γ synthesis by mitogen-activated lymphocytes and increased nitric oxide production in LPS-stimulated chBMMs. The results confirm that IL-10 is an inducible feedback regulator of immune response in chickens, and could be the target for improved vaccine efficacy or breeding strategies., Highlights • Five mouse mAbs to chicken IL-10 was produced. • Two capture ELISA assays were developed to quantify native IL-10. • Three mAbs (ROS-AV162, 163 and 164) neutralised the bioactivities of chIL-10. • Anti-IL-10 antibodies detected intracellular IL-10 in only a subset of LPS-stimulated macrophages. • Eimeria infection of chickens produced a massive increase in circulating IL-10.

A new member of the chicken TNF superfamily has recently been identified, namely receptor activator of NF-κB ligand (RANKL), as have its signalling receptor, RANK, and its decoy receptor, osteoprotegerin (OPG). In mammals, RANKL and RANK are transmembrane proteins expressed on the surface of Th1 cells and dendritic cells (DC) respectively, whereas OPG is expressed as a soluble protein from osteoblasts and DC. Recombinant soluble chicken RANKL (chRANKL) forms homotrimers whereas chicken OPG (chOPG) forms homodimers, characteristic of these molecules in mammals. ChRANKL, chRANK and chOPG are expressed at the mRNA level in most tissues and organs. ChRANKL is transcriptionally regulated by Ca(2+) mobilisation and enhances the mRNA expression levels of pro-inflammatory cytokines in bone marrow-derived DC (BMDC); this is inhibited by both chOPG-Fc and soluble chRANK-Fc. However, chRANKL does not enhance the expression of cell surface markers in either BMDC or BM-derived macrophages (BMM). Furthermore, chRANKL enhances the survival of APC similar to its mammalian orthologue.

For poultry as well as for mammalian species used for scientific research, many immunocytochemical techniques have been developed to investigate in detail the interaction between infectious micro-organisms and the nonspecific and specific immune systems of the host. In this review three techniques have been described with all technical details necessary to perform them correctly: (1) single immunocytochemical staining to detect the infectious micro-organisms in situ at their site of infection, (2) double immunocytochemical staining to visualize simultaneously the infectious micro- organism and the host cellular response to investigate their interactions, and (3) detection of plasma cells producing antibodies specific to the micro- organism. Of the three techniques the results are described when applied on chicken tissues infected with various micro-organisms, such as Marek's disease virus, chicken anemia virus, infectious bursal disease virus and Eimeria tenella. (C) 2000 Elsevier Science Ltd.