Binding of naturally occurring antibodies to oxidatively and nonoxidatively modified erythrocyte band 3.
Both oxidative clustering (elicited by diamide treatment) and nonoxidative clustering (elicited by zinc/BS3 (bis[sulfosuccinimidyl]suberate) treatment) of erythrocyte integral membrane proteins induce binding of autologous antibodies with anti-band 3 specificity, followed by complement deposition and phagocytosis. Autologous antibodies eluted from nonoxidatively clustered erythrocytes bind to and stimulate phagocytosis of oxidatively damaged erythrocytes. Those eluted antibodies bind specifically to disulfide-crosslinked band 3 dimers generated by diamide treatment. Band 3 dimerization and antibody binding are abrogated by cleavage of band 3 cytoplasmic domain. Thus, disulfide-crosslinked band 3 dimers are the minimal band 3 aggregate with enhanced affinity for anti-band 3 antibodies. The eluted antibodies do not bind to band 3 dimers generated nonoxidatively by BS3 treatment but bind avidly to larger band 3 clusters generated nonoxidatively by zinc/BS3 treatment. Possibly, disulfide crosslinking of cytoplasmic domain cysteines induces reorientation of intramembrane domains as to expose putative anti-band 3 epitopes and allow bivalent binding of anti-band 3 antibodies. Extensive nonoxidative band 3 clustering appears to disrupt the native band 3 conformation and generate reoriented dimers which expose putative anti-band 3 epitopes in the proper distance and orientation as to allow bivalent antibody binding.
Turrini
F
F
Dipartimento di Genetica, Biologia, Chimica Medica, Università di Torino, Italy.
Mannu
F
F
Cappadoro
M
M
Ulliers
D
D
Giribaldi
G
G
Arese
P
P
D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000906:Antibodies / Q000378:metabolism*; D003165:Complement System Proteins / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000302:isolation & purification / Q000378:metabolism; D008565:Membrane Proteins / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010587:Phagocytosis; D013388:Succinimides; D015032:Zinc
D001457:Anion Exchange Protein 1, Erythrocyte; D000906:Antibodies; D007074:Immunoglobulin G; D008565:Membrane Proteins; D013388:Succinimides; D003165:Complement System Proteins; C035760:bis(sulfosuccinimidyl)suberate; D015032:Zinc