Comparison of the measurement of surface or total platelet‐associated IgG in the diagnosis of immune thrombocytopenia

Kelton, John G.; Denomme, Gregory A.; Lucarelli, Ann; Garvey, Judy; Powers, Peter; Carter, Cedric

doi:10.1002/ajh.2830180102

Cited by 22 publications

(6 citation statements)

References 12 publications

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“…Normal controls, patients with ITP and non-immune thrombocytopenic patients are presented in relation to the upper normal ranges, 2 SD above the normal mean values. Reprinted with permission.26 per platelet.23 24 Despite the many different assays and reporting laboratories, there is remarkable agreement on this figure. It has been determined that the majority of PAIgG is found within a granules in the platelet and that less than 1 % is on the platelet surface.2' 22…”

Section: Total Platelet Associated Igg (Paigg)mentioning

confidence: 88%

Laboratory investigation of immune thrombocytopenia.

Warner

Kelton²

1997

J Clin Pathol

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Section: Total Platelet Associated Igg (Paigg)mentioning

confidence: 88%

Laboratory investigation of immune thrombocytopenia.

Warner

Kelton²

1997

J Clin Pathol

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“…This assay was performed using an immunoradiometric (IRMA) assay described previously (Kelton et al, 1985). A standard curve was generated by testing dilutions of pre-quantitated IgG in the same assay.…”

Section: Methodsmentioning

confidence: 99%

A prospective study of protein‐specific assays used to investigate idiopathic thrombocytopenic purpura

et al. 1999

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Summary. Idiopathic thrombocytopenic purpura (ITP) is a disorder in which platelets, sensitized by autoantibodies, are destroyed by the reticuloendothelial system. The diagnosis of ITP has been a clinical one because assays measuring platelet-associated IgG (PAIgG) have low specificity. The recently introduced assays that measure antibodies against specific platelet glycoproteins (GP) offer the possibility of improved specificity. In this report we describe two prospective studies. In the first study we compared two proteinspecific assays (AC and MAIPA) looking for the presence of autoantibodies against GP IIb/IIIa in 81 patient samples. These results were compared with an immunoradiometric assay for PAIgG. The second study investigated the enhanced sensitivity of measuring anti-GP Ib/IX autoantibodies in 76 patient samples. The protein-specific assays were able to differentiate immune from non-immune thrombocytopenia (specificity 91%, sensitivity 39%), whereas the PAIgG assay could not (specificity 19%, sensitivity 78%). The addition of the Ib/IX AC assay maintained a specificity of 92% while increasing the diagnostic sensitivity to 66%. In contrast to the PAIgG assay, there was no correlation between the platelet count and the likelihood or degree of positivity within the control samples using the glycoprotein assays. These studies confirm that glycoprotein assays can be used as diagnostic tests for ITP.

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“…Phase II assays were designed to measure either surface or total PAIgG [7,8]. However, it was later shown that PAIgG was elevated in a wide spectrum of nonimmune TP disorders.…”

Section: Introductionmentioning

confidence: 99%

Prospective evaluation of a new platelet glycoprotein (GP)-specific assay (PakAuto) in the diagnosis of autoimmune thrombocytopenia (AITP)

et al. 2005

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Assays measuring platelet-associated immunoglobulin G (PAIgG), while highly sensitive, lack specificity in diagnosing autoimmune thrombocytopenia (AITP). We prospectively evaluated a new commercially available glycoprotein (GP)-specific assay, the PakAuto (GTI, Brookfield, WI), for its clinical usefulness in distinguishing immune from nonimmune thrombocytopenia (TP), in 216 patients with autoimmune TP (both primary ''idiopathic'' and ''secondary'') and 46 patients with TP due to other causes. This assay is designed to detect both platelet-associated (direct assay) and plasma (indirect assay) antiplatelet antibodies specific for GPs IIb/IIIa, Ib/IX, and Ia/IIa. The mean platelet counts of the immune (79 ± 7 · 10 9 /L) and nonimmune groups (78 ± 7 · 10 9 /L), were similar (P = 0.95). The direct assay was positive in 114/216 patients with AITP (53%), and 13/46 with nonimmune TP (28%). Among the AITP group, the majority (61%) of patients with positive test results had autoantibodies reactive against all three GP targets. The sensitivity, specificity, positive, and negative predictive values for the direct PakAuto were 53%, 72%, 90%, and 24%, respectively, comparable to previously published experience of GP-specific assays. However, in some cases of TP due to nonimmune cause, the PakAuto was highly specific. Only 3 of 22 patients with gestational and 1 of 8 with familial/congenital TP had a positive direct assay, indicating that the test may be particularly useful for excluding an immune etiology for TP in certain patient subgroups. Am.

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Comparison of the measurement of surface or total platelet‐associated IgG in the diagnosis of immune thrombocytopenia

Cited by 22 publications

References 12 publications

Laboratory investigation of immune thrombocytopenia.

Laboratory investigation of immune thrombocytopenia.

A prospective study of protein‐specific assays used to investigate idiopathic thrombocytopenic purpura

Prospective evaluation of a new platelet glycoprotein (GP)-specific assay (PakAuto) in the diagnosis of autoimmune thrombocytopenia (AITP)

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