The human OX40L extracellular domains, consisting of amino acids 51-183, with an IgG-Fc tag linked to a N-terminal 10x-histidine sequence. OX40L, also known as CD252, is a protein that functions as a co-stimulatory molecule in the immune system. It is typically expressed on the surface of activated antigen-presenting cells such as dendritic cells, B cells, and macrophages, and interacts with its receptor, OX40, on activated T cells to enhance their survival, proliferation, and effector function. OX40L/OX40 signaling has been shown to be important in immunity against a variety of pathogens as well as in the regulation of immune responses in autoimmune diseases, cancer, and transplantation.