A monoclonal antibody specific for rat IL-18BP and its application in determining serum IL-18BP.

IL-18 binding protein (IL-18BP) is a soluble inhibitory receptor for IL-18, a proinflammatory cytokine that plays a major role in IL-12-driven Th1 cell differentiation. IL-18BP is presumed to play a vital regulatory function in IL-18-mediated immune responses, although its precise role in immunomodulation in various diseases is not well understood. In the present study, we have generated and characterized a mouse monoclonal antibody (2A6H11), specific for rat IL-18BP. Its binding epitope is within amino acids 29-60 on IL-18BP and it does not interfere with the function of IL-18BP. Using this monoclonal antibody, we have developed an ELISA for determining IL-18BP levels. We observed elevated levels of IL-18BP in sera of rats with experimental autoimmune myasthenia gravis (EAMG), in comparison with the levels in healthy rats. Thus, this monoclonal antibody can serve as a valuable tool to elucidate the role of IL-18BP in EAMG and in other rat models for autoimmune diseases.