Platelet-associated immunoglobulin G in childhood idiopathic thrombocytopenic purpura

Micromethod for demonstrating increased platelet surface immunoglobulin G: Findings in acute, chronic, and human immunodeficiency virus‐1‐related immunologic thrombocytopenias

“…This is in contrast to two other pediatric studies that have reported the level of platelet-associated IgG to be higher in acute ITP at time of presentation than in chronic ATP [15,16]. It has been suggested that this finding may have been an artefact due to the fact that platelet counts in acute ITP at onset are frequently lower than in chronic, as was the case in one of these studies [15]. Because the subjects were young children, a smaller volume of blood than usual was drawn, providing too few platelets, perhaps resulting in a spuriously low total platelet count.…”

“…The mean value was higher in those with chronic ATP, probably due to the presence of normal values in five of the ITP children (see below). This is in contrast to two other pediatric studies that have reported the level of platelet-associated IgG to be higher in acute ITP at time of presentation than in chronic ATP [15,16]. It has been suggested that this finding may have been an artefact due to the fact that platelet counts in acute ITP at onset are frequently lower than in chronic, as was the case in one of these studies [15].…”

Acute idiopathic thrombocytopenic purpura in children

“…In the chronic state antibodycoated platelets are probably removed by the reticuloendothelial system as in adults. In acute ITP however, as mean platelet-associated IgG levels were eight times hgher than the calculated antigen-saturating quantity of platelet-bound IgG determined from ITP spleen culture studies using McMillan's method [37], it is speculated that viral infections trigger formation of immune complexes [36]. These immune complexes could be surface absorbed to platelet receptors, making the Fc fragment less available to macrophages, or they could be phagocytized, with resultant platelet alteration and susceptibility to reticuloendothelial removal [36].…”

“…Luiken et al, using the Fab-anti-Fab assay, demonstrated significantly higher levels of platelet-associated IgG in six children with acute ITP than in 3 1 individuals with the chronic form of the disease [35]. In a larger series that included children only, Lightsey et al have recently confirmed this finding [36]. While levels of platelet-associated IgG were higher in all children with ITP than in normals (P < 0.001), those with acute ITP (achievement of normal platelets within six months of diagnosis without subsequent relapse) had even higher levels (P < 0.003) than those with chronic ITP (persistent thrombocytopenia longer than six months from diagnosis).…”

Intravenous Gamma-Globulin (Sandoglobulin®) Therapy in the Management of Four Patients with Immune Thrombocytopenic Purpura

“…We do not believe that these results reflect a lack of sen sitivity for the RID assay, since elevated PAIgG levels have been reported with this assay in 93% of adults with ITP [9] and by us in 77% of children evaluated with this disor der [1], However, our series is small and the issue is important enough to merit continued investigation. In vitro studies in 1 patient (case 4) clearly indicate that IgG in the San doglobulin preparation does bind to platelets, and our data suggest a dose-response relation autonomous formation of platelet antibody, and thus, the chronic form of the disorder [7], one could argue in favor of pretreatment with high-dose intravenous Sandoglobulin to re verse thrombocytopenia and allow subse quent plasma exchange therapy to remove immune complexes. However, raised levels of circulating immune complexes cannot be demonstrated in all cases of ITP.…”