Glycoprotein V-specific platelet-associated antibodies in thrombocytopenic patients.
In autoimmune thrombocytopenia, platelet-associated IgG (PA-IgG) frequently displays specificity against glycoprotein (GP) IIbIIIa and/or GP IbIX. Because in a high proportion of patients positive PA-IgG may not be explained by these GP specificities, studies on other target proteins are needed. We studied the presence of GP V-specific PA-IgG by direct monoclonal antibody-specific immobilization of platelet antigens (MAIPA) with the monoclonal antibody SW16. We focused on 69 consecutive random patients with histories of thrombocytopenia who were strongly positive for PA-IgG detected by the direct platelet immunofluorescence test (PIFT). PA-IgG against GP V (ratio > or = 1.5) was noted in 15 (22%) patients. The degree of PA-IgG measured by PIFT, and of GP IIbIIIa-and/or GP IbIX-specific PA-IgG measured by direct MAIPA, correlated directly with the GP V-specific PA-IgG (P < 0.001). In one patient, GP V-specific antibodies were associated with quinidine-induced thrombocytopenia. Although this patient had strongly positive GP V-specific PA-IgG, she remained negative in GP IIbIIIa- and GP IbIX-specific direct MAIPA. Two patients studied because of thrombocytopenia associated with gold therapy had strongly positive GP V-specific PA-IgG. In one patient with rheumatoid arthritis and severe gold-induced thrombocytopenia, the amount of GP V-specific PA-IgG decreased during the recovery phase. Thus, GP V may represent an important target antigen in autoimmune-mediated thrombocytopenia, especially in drug-induced thrombocytopenia.
Joutsi-Korhonen
L
L
Finnish Red Cross Blood Transfusion Service, Helsinki, Finland Jorvi Hospital, Espoo, Finland.
Javela
K
K
Hormila
P
P
Kekomäki
R
R
D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects; D001172:Arthritis, Rheumatoid / Q000139:chemically induced / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006493:Heparin / Q000009:adverse effects; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D050607:Organogold Compounds; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000209:etiology / Q000276:immunology; D011802:Quinidine / Q000009:adverse effects; D013921:Thrombocytopenia / Q000139:chemically induced / Q000209:etiology / Q000276:immunology*
D018501:Antirheumatic Agents; D001323:Autoantibodies; D007074:Immunoglobulin G; D050607:Organogold Compounds; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D006493:Heparin; D011802:Quinidine