CD59, also known as the MAC-inhibitory protein, is a complement regulatory glycoprotein that inhibits membrane attack complex formation by preventing C9 from polymerizing. The soluble form of CD59 can be detected in a variety of body fluids and is associated with a range of different conditions. A paper from 1995 for example describes the role of CD59 in glomerulonephritis and in that same year there was a paper discussing the therapeutic potential of CD59 in inflammatory diseases.

Historically there have also been scientific articles specifying the role of this protein in relation to myocardial infarction, carcinoma, PNH and macular degeneration. The glycated form of CD59 also shows to be a useful marker for diabetes. Recent insights have further demonstrated that the soluble form of CD59 plays an important role in allograft rejection after transplantation. All these findings combined confirm that CD59 is a versatile regulatory protein that will remain a relevant target for scientific exploration of complement-mediated conditions.