Association of autoantibodies against platelet glycoproteins Ib/IX and IIb/IIIa, and platelet-reactive anti-HIV antibodies in thrombocytopenic narcotic addicts

• Published in: British journal of haematology Vol. 93; no. 2; p. 464
• Main Authors: Gonzalez-Conejero, R, Rivera, J, Rosillo, M C, Cano, A, Rodriguez, T, Vicente, V
• Format: Journal Article
• Language: English
• Published: England 01.05.1996
• Subjects: Adult; Antigens, Human Platelet; Autoantibodies - analysis; Autoantibodies - immunology; Blotting, Western; Enzyme-Linked Immunosorbent Assay; Female; HIV Antibodies - analysis; HIV Antibodies - immunology; Humans; Immunoglobulin G - analysis; Male; Opioid-Related Disorders - complications; Opioid-Related Disorders - immunology; Platelet Glycoprotein GPIb-IX Complex - immunology; Platelet Glycoprotein GPIIb-IIIa Complex - immunology; Substance Abuse, Intravenous - complications; Substance Abuse, Intravenous - immunology; Thrombocytopenia - immunology; Thrombocytopenia - virology
• ISSN: 0007-1048
• DOI: 10.1046/j.1365-2141.1996.00502.x

The levels of platelet-associated Igs (PAIgs) and plasma circulating antiplatelet antibodies were evaluated by a flow cytometric immunofluorescence assay (FCIFA), an enzyme-linked immunoassay (ELISA), and a platelet radioactive antiglobulin test (PRAT), in a group of 45 human immunodeficiency virus (HIV)-infected intravenous drug users (IVDUs), with or without thrombocytopenia (TCP). Direct tests demonstrated an increased amount of PAIgs in 40% of the patients, irrespective of their platelet count. These PAIgs were mainly of IgG class and could not be eluted with ether. Plasma IgG with antiplatelet activity was found in 70% of the thrombocytopenic individuals, whereas it was detected in only one patient without TCP. The relative frequencies of antibodies against the platelet glycoproteins (GPs) Ib/IX and IIb/IIIa were assessed in plasma from all patients by means of the monoclonal antibody-specific immobilization of platelet antigens assay (MAIPA). Plasmas from all non-thrombocytopenic patients were negative when tested by indirect MAIPA. In contrast, 10/23 plasma from thrombocytopenic patients reacted with either GP IIb/IIIa, GP Ib/IX, or both GPs. Finally, aiming to investigate whether HIV antibodies from these patients are reactive with normal platelets, we performed absorption-elution experiments, followed by evaluation of HIV antibodies in the indirect eluates by ELISA and Western blot. Interestingly, we detected anti-HIV antibodies that bind to normal platelet antigens in 50% of the ether eluates prepared from control platelets sensitized with plasma from patients with TCP, but in only 5% of eluates obtained from platelets sensitized with plasma from non-thrombocytopenic patients. The present study provides direct evidence that specific autoantibodies against platelet membrane GPs Ib/IX and IIb/IIIa are common in HIV positive thrombocytopenic individuals. The finding in these patients of HIV antibodies cross-reactive with normal platelets, suggests that mimicry of human antigens by HIV could play a key role in the pathophysiology of the HIV-related TCP.