GPI-anchored complement regulatory proteins in seminal plasma. An analysis of their physical condition and the mechanisms of their binding to exogenous cells.

Abstract

We analyzed and compared the properties of three glycosylphosphatidylinositol (GPI)-anchored proteins, CD59, CD55 (both C regulators), and CDw52, and of the transmembrane C regulator CD46 in seminal plasma (SP). We demonstrated previously that anchor-intact SP CD59 is present on the membranes of vesicles (prostasomes) and that cells acquire this protein during incubation with SP. We now report that this acquisition is due partly to adherence of prostasomes to cells and partly to a second mechanism which may involve micellar intermediates. Using fluorescent labeling, ultracentrifugation, and density gradient centrifugation, virtually all CD46 was present on prostasomes whereas CD59, CD55, and CDw52 were also detected in a form which remained in the 200,000 g supernatant and equilibrated at higher density than prostasomes in gradients. All three GPI-linked proteins eluted at high molecular mass during size exclusion chromatography of this nonprostasome

Male-specific Modification of Human CD52

“…Microheterogeneity patterns of sperm and seminal plasma CD52 were similar (Fig. 1a), however, the staining intensity of comparable amounts of sperm extract was always much lower (approximately 10%) than that of cell-free seminal plasma, corroborating previous enzyme-linked immunosorbent assay data that there is substantially more CD52 antigen in seminal plasma than on sperm (9,12). PNGase F-digestion converted the heterogeneous Ϸ15-20 kDa immunoreactivity into a single band of Ϸ6 kDa (Fig.…”

“…Meanwhile, evidence has been provided that a massive cell-to-cell transfer of GPI-anchored HE5/CD52 occurs in vivo within the male genital tract (10,11). Shedding from the epididymal epithelium of vesicles or of micellar intermediates may be involved interacting with the spermatozoa (12).…”

Free circulating soluble CD52 as a tumor marker in chronic lymphocytic leukemia and its implication in therapy with anti‐CD52 antibodies

“…[1][2][3] The C-terminus is anchored on the cell membrane by a glycosylphosphatidylinositol (GPI) lipid. 2,4 CD52 is expressed on the surface of T and B lymphocytes, monocytes/macrophages, eosinophils, and on some early hematopoietic cells. [5][6][7][8] It is also expressed in the male reproductive tract.…”

Surface Modification of Retroviral Vectors for Gene Therapy

“…GPI proteins can also be found in serum and other body fluids both with intact or absent GPI anchors (Landi et al 2003). Processes that release GPI-linked proteins into the medium with intact GPI anchors are reversible and it has been shown in a variety of in vitro and in vivo systems that GPI-linked proteins can be re-inserted into cell membranes (Dunn et al 1996;Kooyman et al 1995;Rifkin and Landsberger 1990;Rooney et al 1993;Rooney et al 1996;Vakeva et al 1994). Transfer has been demonstrated for CD59 from erythrocytes to endothelial cells (Kooyman et al 1995) as well as for trypanosomal variant surface glycoprotein (VSG) to erythrocytes of infected patients (Rifkin and Landsberger 1990).…”