CD126. also known as interleukin-6 receptor (IL-6R), is a transmembrane protein that plays a critical role in mediating inflammatory and immune responses. It is part of the interleukin-6 (IL-6) signaling pathway, which regulates processes such as cell proliferation, differentiation, and acute-phase immune reactions. IL-6R exists in two forms: a membrane-bound receptor (mIL-6R) on select cells (e.g., hepatocytes, leukocytes) and a soluble receptor (sIL-6R) generated via alternative splicing or proteolytic cleavage. Both forms bind IL-6 to initiate signaling, often through a mechanism called trans-signaling, which expands the cytokine’s reach to cells lacking mIL-6R.
CD126 antibodies are tools or therapeutics designed to target IL-6R, blocking IL-6-mediated signaling. Monoclonal anti-CD126 antibodies, such as tocilizumab, are FDA-approved for treating autoimmune diseases like rheumatoid arthritis and cytokine release syndrome (e.g., in severe COVID-19). By inhibiting IL-6R, these antibodies suppress excessive inflammation, reducing tissue damage and disease progression. Research-grade CD126 antibodies are also widely used in laboratories to study IL-6 pathway dynamics, immune cell interactions, and disease mechanisms in cancer, chronic inflammation, and metabolic disorders. Their development underscores the therapeutic and experimental importance of modulating IL-6 signaling in immune dysregulation.