Glycoprotein IIb/IIIa autoantigenic repertoire in chronic idiopathic thrombocytopenic purpura.
The objective of the present study was to further disclose the autoantigenic repertoire carried by the platelet glycoprotein (GP) IIb/IIIa complex. IgG-F(ab')2 fragments were prepared from two prototype ITP patients, and their ability to block the binding of GPIIb/IIIa reactive antibodies derived from other patients with ITP was evaluated using a modified MAIPA asay; a PlA1 alloantiserum and 20 normal sera were included as controls. It was found that the two prototype IgG-F(ab')2 fragments were each able to significantly block the binding of serum IgG to GPIIb/IIa in six (55%) and seven (64%) out of 11 patients with chronic ITP, respectively. No significant blocking effect was observed for IgG-F(ab')2 fragments prepared from normal subjects. Also, the binding of the PlA1 alloantiserum to its epitope on GPIIIa was not affected by any of the blocking IgG-F(ab')2 fragments exploited in the study. These data substantiate that in chronic ITP at least half of the GPIIb/IIIa reactive sera bind to homogenous autoepitopes.
Hou
M
M
Department of Medicine, Sahlgrenska University Hospital, University of Göteborg, Sweden.
Stockelberg
D
D
Kutti
J
J
Wadenvik
H
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019138:Antibodies, Blocking / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D001323:Autoantibodies / Q000276:immunology*; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D007158:Immunologic Techniques; D008297:Male; D008875:Middle Aged; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology* / Q000378:metabolism; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000276:immunology*
D019138:Antibodies, Blocking; D001323:Autoantibodies; D007140:Immunoglobulin Fab Fragments; D019039:Platelet Glycoprotein GPIIb-IIIa Complex