The Clinical Significance of Platelet‐Associated IgG: a Study on 298 Patients with Various Disorders

Abstract

Summary. Platelet‐associated IgG (PAIgG) was studied by a quantitative platelet radioactive anti‐IgG test (PRAT) in 298 patients. At the time of investigation, 171 patients were thrombocytopenic (platelet count <100 × 109/1), 127 had normal platelet counts. Patients fell into the following disease categories: Idiopathic thrombocytopenic purpura (ITP) (N=81), possible ITP (19), acute ITP (9), systemic lupus erythematosus (22), autoimmune haemolytic anaemia of warm‐type (18), systemic blood disease (65), liver diseases (35), others (49). A significant elevation of PAIgG was found in all disease categories. There was a significant correlation between PAIgG and the reciprocal values of platelet counts for most disease groups. No relationship was discernible between PAIgG and hypergammaglobulinaemic states (serum IgG >1.8 g/l), Platelet survival studies (N=30) revealed that normal and increased values of PAIgG were associated with normal or shortened platelet mean life span. It is concluded that an elevated PAIgG is only one of several factors involved in the development of immunologically mediated thrombocytopenia.

Autoimmune thrombocytopenia in response to splenectomy in cirrhotic patients with accompanying hepatitis C

“…Similar PAIgG and platelet levels following splenectomy are commonly found in ITP patients, in whom the thrombocytopenia is responsible for the autoimmune mechanism mediated by a specific IgG bound to platelet membrane proteins [24,25] . There exist controversies regarding the clinical significance of PAIgG in pathogenesis of thrombocytopenia in the patients with liver disease [7,14,29,30] . Two studies on partial splenic artery embolization in patients with hypersplenism clearly confirmed an immunological mechanism mediated by PAIgG-induced thrombocytopenia accompanying liver cirrhosis [7,14] .…”

Autoimmune Thrombocytopenia

“…PAIgG has been demonstrated to be inversely proportional to the platelet count and to the mean platelet lifespan (Dixon et al, 1975;Mueller-Eckhardt et al, 1980;Panzer et al, 1986;Nieminen, 1992;Movahed Shariat Panahi et al, 1994). PA-IgG is known to consist mostly of subclasses IgG1 and IgG3 (von dem Taaning & Petersen, 1988;Tijhuis et al, 1991).…”

“…Moreover, increased PA-IgG has been reported in varying proportions of patients with thrombocytopenia that is presumably not of immunological origin (Helmerhorst et al, 1982b;Kelton et al, 1982). With the quantitative platelet radioactive antiglobulin test, Mueller-Eckhardt et al (1980) demonstrated large amounts of PA-IgG in patients with systemic blood diseases, such as leukaemias or lymphomas and hepatic or infectious disorders. Warner et al (1999) Movahed Shariat Panahi et al, 1994).…”

“…Some other studies on PA-IgG are listed in Table 3. However, the specificity of PA-IgG in the diagnosis of ITP is less than 30% (Mueller-Eckhardt et al, 1980;Kelton et al, 1982).…”

“…Moreover, in the platelet radioactive antiglobulin test, radioactive 125 I-labelled anti-IgG is bound to the IgG on the platelet surface, and the amount of radioactivity is measured to obtain the amount of PA-IgG (Soulier et al, 1975;Mueller-Eckhardt et al, 1980; Table 3). Court et al, 1987 ELISA TP (children) 17 16 (94) Taaning & Petersen, 1988 PIFT ITP 109 88 (81) Nieminen, 1990 Immunobead assay (Table 3).…”