Development of a sandwich immunoassay for the detection of soluble bovine interleukin-2 receptor-alpha (sIL-2R-alpha) and its use to measure cell-mediated immunity in cattle.
Stimulation of T-lymphocytes with mitogens or antigens results in the production of the cytokine interleukin-2, which exerts its physiological effect by interacting with a specific IL-2 receptor on the cell surface. The alpha-chain of this receptor is induced and expressed on the cell surface after lymphocyte activation. Following continuous antigen stimulation, a smaller soluble form of this alpha-subunit (sIL-2R-alpha) is shed from the membrane of activated cells. This study describes a sandwich ELISA for bovine sIL-2R-alpha that was developed using monoclonal antibodies specific for bovine IL-2R-alpha (CD 25). The feasibility of using sIL-2R-alpha released by activated T-lymphocytes as an in vitro marker of cell-mediated immunity (CMI) in cattle is demonstrated. Calves were immunized with the foreign protein keyhole limpet haemocyanin (KLH) and the development of CMI was followed using sIL-2R-alpha release, IFN-gamma production and lymphocyte proliferation assay. The results showed that the release of sIL-2R-alpha by previously sensitized cells following stimulation with antigen is likely to be a useful marker of CMI in infectious diseases, and in the study of T cell antigens and/or novel vaccines. Using appropriate detection systems, the measurement of sIL-2R-alpha may also prove to be a useful marker of CMI in other species.
Nualláin
E M
EM
Department of Large Animal Clinical Studies, Faculty of Veterinary Medicine, University College Dublin, Ireland.
Davis
W C
WC
Fisher
A D
AD
Monaghan
M L
ML
D000818:Animals; D000911:Antibodies, Monoclonal; D015415:Biomarkers / Q000032:analysis; D002417:Cattle; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000096:biosynthesis; D007700:Kinetics; D008213:Lymphocyte Activation; D015375:Receptors, Interleukin-2 / Q000032:analysis / Q000096:biosynthesis*; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors
D000911:Antibodies, Monoclonal; D015415:Biomarkers; D015375:Receptors, Interleukin-2; D007371:Interferon-gamma