Glycoprotein V: the predominant target antigen in gold-induced autoimmune thrombocytopenia.
Autoimmune thrombocytopenia is generally caused by autoantibodies against glycoprotein (GP) IIb-IIIa or GPIb-IX and occasionally against GPIa-IIa or GPV. By investigating 38 rheumatoid arthritis (RA) patients on gold therapy, 10 with profound thrombocytopenia and 28 nonthrombocytopenic controls, we showed that in all 10 patients with thrombocytopenia, the platelet autoantibodies preferentially targeted GPV but the presence of gold was not required for their reactivity. Elevated levels of platelet-associated IgG (PAIgG) were observed in 8 of the 10 patients in whom the tests were performed. In 5 patients with sufficient autologous platelets, the GPV specificity of PAIgG was confirmed. Tests with GPV transfectants revealed that the antibodies reacted with GPV independent of GPIb alpha, GPIb beta, or GPIX. Autoantibodies recognizing GPV were not seen in the 28 nonthrombocytopenic control RA patients. Thus, GPV seems to be targeted in gold-induced autoimmune thrombocytopenia.
Garner
Stephen F
SF
Division of Transfusion Medicine, University of Cambridge and National Blood Service East Anglia Centre, United Kingdom. sfg21@cam.ac.uk
Campbell
Kate
K
Metcalfe
Paul
P
Keidan
Jane
J
Huiskes
Elly
E
Dong
Jing-Fei
JF
López
José A
JA
Ouwehand
Willem H
WH
D001172:Arthritis, Rheumatoid / Q000150:complications / Q000188:drug therapy; D001323:Autoantibodies / Q000097:blood; D006046:Gold / Q000009:adverse effects* / Q000097:blood / Q000627:therapeutic use; D006801:Humans; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000139:chemically induced / Q000276:immunology*
D001323:Autoantibodies; D019038:Platelet Glycoprotein GPIb-IX Complex; D006046:Gold