CD137/4-1BB  is a member of the tumor necrosis factor receptor family, expressed mainly on activated T lymphocytes, to a larger extent on CD8 than on CD4 T cells. CD137/4-1BB expression is also found on many other immune cells such as B cells, monocytes and granulocytes, etc.  CD137/4-1BB regulates the activation and proliferation of immune cells and may induce apoptosis (programmed cell death) of activated lymphocytes. The best characterized activity of CD137/4-1BB is its costimulatory activity for activated T cells. Crosslinking of CD137/4-1BB enhances T cell proliferation, IL-2 secretion survival, and cytolytic activity. It has also been demonstrated that CD137/4-1BB signaling can enhance immune activity to eliminate tumors in mice.

Soluble form of CD137/4-1BB (sCD137/4-1BB) is also expressed by activated lymphocytes. Expression of sCD137/4-1BB in lymphocytes requires strong activation, and levels of sCD137/4-1BB correlate negatively with lymphocyte proliferation and positively with the degree of activation-induced cell death caused by mitogen overstimulation. Since activation of lymphocytes through membrane-bound CD137/4-1BB delivers a potent stimulatory signal, sCD137/4-1BB may provide a negative control mechanism for immune responses. sCD137/4-1BB can be detected at enhanced concentrations in sera of patients suffering from various autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. The levels of sCD137/4-1BB have been reported to reflect a negative feed-back control of inflammation in some autoimmune diseases.

BioLegend’s LEGEND MAX™ Human Soluble CD137/4-1BB ELISA Kit is a sandwich Enzyme-Linked Immunosorbent Assay (ELISA), in which, a human soluble CD137/4-1BB -specific monoclonal antibody is pre-coated on a 96-well strip-well plate.

BioLegend’s LEGEND MAX™ Human Soluble CD137/4-1BB ELISA Kit is specifically designed for the accurate quantitation of Human Soluble CD137/4-1BB from cell culture supernatant, serum, plasma or other bodily fluids. It is ready-to-use, accurate, and sensitive.