Effect of serum derived blocking factor (SDBF) on platelet associated-IgG.
We analyzed the effect of an unknown factor, which derived from serum, on platelet associated IgG (PA-IgG) and we established the novel immunofluorescence method to measure the level of PA-IgG. Blood samples were obtained from 20 patients with idiopathic thrombocytopenic purpura (ITP). After the treatment of platelets with neuraminidase, the value of PA-IgG positive platelets (%PA-IgG) were significantly increased in patients with ITP, but not in controls. When the platelets pretreated with neuraminidase were incubated with human serum, %PA-IgG was remarkably decreased in ITP patients. In healthy individuals, when platelets bound to aggregated human IgG pretreated with human serum, the binding of FITC-conjugated anti-human IgG was inhibited. And the value of mouse anti-GP II b/III a monoclonal antibody positive platelets was decreased, when the platelets preincubated with mouse serum. The binding of FITC-conjugated anti-human IgG and anti-mouse IgG antibody was apparently inhibited by some unknown factor in serum. Our results showed that this substance had species specificity. We called this substance "Serum Derived Blocking Factor (SDBF)".
Honda
J
J
First Department of Internal Medicine, Kurume University of Medicine, Fukuoka, Japan.
Hoshino
T
T
Natori
H
H
Oizumi
K
K
Shitijo
S
S
Yokoyama
M
M
D000293:Adolescent; D000328:Adult; D000818:Animals; D001667:Binding, Competitive; D001792:Blood Platelets / Q000187:drug effects / Q000276:immunology*; D002648:Child; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008875:Middle Aged; D009439:Neuraminidase / Q000494:pharmacology; D010974:Platelet Aggregation; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000276:immunology*; D013045:Species Specificity
D007074:Immunoglobulin G; D009439:Neuraminidase