This non-therapeutic biosimilar antibody uses the same variable regions from the therapeutic antibody Ipilimumab making it ideal for research use. This Ipilimumab biosimilar reacts with human CTLA-4 (cytotoxic T lymphocyte antigen-4) also known as CD152. CTLA-4 is a 33 kDa cell surface receptor encoded by the Ctla4 gene that belongs to the CD28 family of the Ig superfamily. CTLA-4 is expressed on activated T and B lymphocytes. CTLA-4 is structurally similar to the T-cell co-stimulatory protein, CD28, and both molecules bind to the B7 family members B7-1 (CD80) and B7-2 (CD86). Upon ligand binding, CTLA-4 negatively regulates cell-mediated immune responses. CTLA-4 plays roles in induction and/or maintenance of immunological tolerance, thymocyte development, and regulation of protective immunity. CTLA-4 is among a group of inhibitory receptors being used as cancer treatment targets through immune checkpoint blockade. Ipilimumab binds to CTLA-4, blocking the inhibitory signal, which allows the cytotoxic T cells to kill cancer cells.