Association of autoantibodies against platelet glycoproteins Ib/IX and IIb/IIIa, and platelet-reactive anti-HIV antibodies in thrombocytopenic narcotic addicts.
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.
Gonzalez-Conejero
R
R
Unit of Haematology and Haemotherapy, Hospital General Universitario, Murcia, Spain.
Rivera
J
J
Rosillo
M C
MC
Cano
A
A
Rodriguez
T
T
Vicente
V
V
D000328:Adult; D016824:Antigens, Human Platelet; D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015483:HIV Antibodies / Q000032:analysis* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008297:Male; D009293:Opioid-Related Disorders / Q000150:complications / Q000276:immunology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology*; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000276:immunology; D013921:Thrombocytopenia / Q000276:immunology* / Q000821:virology
D016824:Antigens, Human Platelet; D001323:Autoantibodies; D015483:HIV Antibodies; D007074:Immunoglobulin G; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex