Soluble CD59-Antigen Levels are Increased in Renal Disease Plasma

Cluster of Differentiation antigen 59 (CD59) is a glycosyl phosphatidylinositol-linked protein that protects cells from damage by lytic terminal complexes of complement. Soluble forms of CD59 in serum have been little investigated in disease states. In the present study, by using a sandwich ELISA, reactivities with antibodies to CD59 were compared for sera and plasma from normal individuals and those with renal, leukemia, heart, liver and lung diseases. In all of 44 renal patients, reactivities were up to three-fold higher than those of normals and patients with other conditions. The soluble CD59-related antigen displayed epitopes recognized by an anti-CD59 rabbit antiserum and CD59 monoclonal antibodies MEM-43 and YTH 53.1. Failure to bind the hydrophobic matrix phenyl Sepharose suggested that the CD59-related antigen lacked a membrane-anchoring structure. Although the cellular origin of soluble CD59-related antigen is unknown, some effect common to different renal diseases can promote increased plasma levels of this antigen. In two individuals, monitored before and after renal transplantation, plasma levels of CD59-related antigen decreased towards normal after receipt of a kidney.