Proteolytic elimination of decay-accelerating factor (DAF): lytic abnormality coincides with removal of DAF in papain-treated human erythrocytes.
Erythrocytes (E) from patients with paroxysmal nocturnal hemoglobinuria (PNH) lack decay-accelerating factor (DAF) and this partly causes increasing susceptibility of the E to complement. Several reagents have been used to convert normal E to the complement-sensitive (PNH-like) cells. The relationship between DAF amounts and complement susceptibility of these PNH-like cels has been examined. Of the reported reagents for preparation of PNH-like cells, 2-amino-ethylisothiouronium bromide (AET), papain, and periodate efficiently converted normal E to the complement-sensitive cells, but only papain reduced the quantity of DAF on the cells. Further, of the proteases we tested only papain cleaved DAF to liberate its major fragment from the cells. The papain-treated cells lysed in a similar fashion to PNH cells as the serum concentration increased. The major papain-digested product of DAF had Mr, 55,000, lacked hydrophobicity, and retained the ability to inhibit the C3 convertases. These findings suggest that papain allows liberation from cells of functional domains as well as most of the antigenic epitopes of DAF to generate a PNH-like cell.
Seya
T
T
Center for Adult Diseases, Osaka, Japan.
Inoue
H
H
Okada
M
M
Matsumoto
M
M
Kitamura
H
H
Kinoshita
T
T
Akedo
H
H
D001798:Blood Proteins / Q000378:metabolism*; D018958:CD55 Antigens; D003169:Complement Inactivator Proteins / Q000378:metabolism*; D003170:Complement Pathway, Alternative; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006457:Hemoglobinuria, Paroxysmal / Q000097:blood; D006801:Humans; D008565:Membrane Proteins / Q000097:blood*; D010206:Papain
D001798:Blood Proteins; D018958:CD55 Antigens; D003169:Complement Inactivator Proteins; D008565:Membrane Proteins; D010206:Papain