Biomedical subjects

T Fukuroi

Publications and source records attributed to T Fukuroi.

27 records · Page 2Linked to original sources

PubMed1992

Anti-glycoprotein IIb/IIIa autoantibodies are reversibly internalized into platelets in idiopathic (autoimmune) thrombocytopenic purpura.

We used flow cytometry to investigate the binding of platelet-binding IgG (PBIgG) to unfixed platelets in idiopathic thrombocytopenic purpura (ITP), including that of anti-glycoprotein (GP) IIb/IIIa antibodies. Anti-GPIIb/IIIa antibodies were detected in 13/64 ITP patients using antigen-capture ELISA and immunoblotting. When unfixed platelets were incubated with ITP plasma, the PBIgG level was significantly higher than after incubation with normal plasma. When 1 microM ADP was added to unfixed platelets, which were incubated with ITP plasma and washed, the PBIgG level increased additively. GMP-140 is a constituent of platelet alpha-granules, and a monoclonal antibody directed against this protein showed weak binding to platelets after 1 microM ADP stimulation. The increase of PBIgG produced by ADP was significantly greater when ITP plasma positive for anti-GPIIb/IIIa antibody was used compared with that obtained using antibody-negative ITP plasma. This increase of PBIgG was markedly inhibited by the removal of extracellular calcium with EDTA or the dissociation of the GPIIb/IIIa complex by EDTA treatment at 37 degrees C. These results suggest that anti-GPIIb/IIIa autoantibodies are internalized by unfixed ITP platelets and stored somewhere other than the alpha-granules. This stored antibody pool can be reversibly redistributed on the platelet surface by weak stimulants such as ADP and a functional GPIIb/IIIa complex appears to be necessary for this to occur.

Adolescent↗

PubMed1992

[Analysis of adhesive proteins on the surface of platelets from the patients with lung cancer: studies in histological type and clinical stage].

Flow cytometry was used to detect platelet-associated fibrinogen (PA-Fbg), platelet-associated fibronectin (PA-FN) and platelet-associated thrombospondin (PA-TSP) on the surface membrane of platelets and plasma (P)-TSP in 30 patients with lung cancer (16 case of adenocarcinoma and 14 of squamous cell carcinoma). ELISA was used to analyze beta-TG and PF4. In the lung cancer group, beta-TG and PF4 were higher than those of a normal control group. PA-Fbg values were correlated with beta-TG and PF4 values. Each adhesive protein had a higher value in the patient than in the normal control group, and the degree of the increase was related to the progression of clinical disease stage. In the squamous cell carcinoma group, the P-TSP value was significantly elevated. Platelet size increased as the clinical stage of the disease progressed. These results suggest the following: 1. An increase in PA-Fbg can indicate the presence of activated platelets. 2. In patients with lung cancer, activated platelets appear in the blood, and their numbers increase as the clinical stage of the disease progresses. 3. Differences in histologic type led to differences in binding adhesive protein.

Adenocarcinoma↗

PubMed1991

Antiplatelet autoantibody-related microparticles in patients with idiopathic (autoimmune) thrombocytopenic purpura.

We used flow cytometry to detect antiplatelet antibody-related microparticles (MP) in 56 patients with idiopathic thrombocytopenic purpura (ITP). We measured MP in platelets following various types of stimulation in two experimental systems. In one system washed platelets were incubated with normal serum which included the complement system, and in the other, washed platelets were incubated with Tyrode's buffer. There were no differences between the two measurement systems in the degree of increase in MP using various agonists. An increase in MP using ITP plasma was found in 12 out of 56 patients. In particular, four patients showed a significant increase in MP in washed platelets (WP) plus serum. Furthermore, the increase in platelet-associated IgM (PAIgM) was significant in these patients. There was also a definite positive correlation between PAIgM and the percentage of MP of WP plus serum. On the other hand, no specificity for MP formation with anti-GPIIb/IIIa or anti-GPIb autoantibodies was observed. IgM antibody-related MP appear to exist in some patients with ITP.

Adolescent↗

PubMed1991

Synergistic action in platelet activation induced by an antiplatelet autoantibody in ITP.

We detected an autoantibody which activated normal platelets in a patient with immune thrombocytopenic purpura and investigated the mechanism by which this autoantibody mediated platelet activation. The patient's IgG induced platelet aggregation and ATP secretion in normal platelet-rich plasma (PRP). IgG-induced aggregation was inhibited by aspirin (ASA), apyrase, a protein kinase C (PKC) inhibitor and two anti-platelet glycoprotein (GP) IIb/IIIa monoclonal antibodies. The increase of aequorin-detected intraplatelet Ca2+ induced by the patient's IgG was extremely slight. Phosphorylation of a 40 kDa protein was induced by the patient's IgG without any obvious phosphorylation of a 20 kDa protein, and was inhibited by a PKC inhibitor but not by ASA. With ASA-treated normal PRP, the patient's IgG failed to induce aggregation itself, but enhanced ADP- or STA2-induced aggregation. Western blotting and immunoprecipitation experiments showed that the patient's IgG reacted to a protein of 36 kDa. These results suggest that the platelet activation induced by this autoantibody depended on both the selective activation of PKC and the slight Ca2+ mobilization induced by thromboxane A2 synthesis, while the aggregation depended on secretion induced by the synergistic action of the above two mechanisms and was mediated through GP IIb/IIIa.

Adenosine Triphosphate↗

PubMed1991

New monoclonal anti-human Fc gamma receptor II antibodies induce platelet aggregation.

We developed two new monoclonal antibodies, designated NNKY3-2 and NNKY4-7, that recognized a 40-kD platelet protein. They appeared to be monoclonal anti-Fc gamma receptor II (Fc gamma RII) antibodies from the results of flow cytometric binding inhibition studies using another monoclonal anti-Fc gamma RII antibody (2E1). The addition of NNKY3-2 or NNKY4-7 to platelet-rich plasma (PRP) led to a typical aggregation pattern preceded by a lag phase, but their addition to washed platelets did not induce aggregation. The aggregation of PRP by these antibodies was inhibited by prostaglandin E1 (PGE1) or staurosporine (protein kinase C inhibitor), whereas it was only slightly affected by a monoclonal anti-GPIIb/IIIa antibody or Arg-Gly-Asp-Ser. Furthermore, these antibodies induced the aggregation of washed platelets plus normal serum, but not that of washed platelets plus heat-treated serum (destruction of complement activity). These results suggest that NNKY3-2 or NNKY4-7-induced aggregation involves an unusual pathway independent of fibrinogen, and that the important factor is the participation of complement. NNKY3-2 and NNKY4-7 may be useful to study the relationship between autoantibodies, the Fc receptor, and complement in idiopathic thrombocytopenic purpura.

Adenosine Diphosphate↗

PubMed1991

Analysis of idiopathic thrombocytopenic purpura patients with antiglycoprotein IIb/IIIa or Ib autoantibodies.

We analyzed the immunological characteristics of patients with idiopathic thrombocytopenic purpura (ITP) and antiglycoprotein (GP) IIb/IIIa or GPIb autoantibodies. Among 101 ITP patients, 32 had anti-GPIIb/IIIa and 19 had anti-GPIb autoantibodies. Thrombocytopenia was more severe in patients with anti-GPIb autoantibodies than in patients without these autoantibodies, whereas ITP patients with anti-GPIIb/IIIa autoantibodies did not develop severe thrombocytopenia. Patients with anti-GPIb autoantibodies showed significant increases of platelet-associated IgM and platelet-associated C3 in comparison with patients without the autoantibodies, despite there being no significant difference in the platelet-associated IgG levels. The lymphocyte subsets and the blastogenic response in patients with anti-GPIb autoantibodies were also significantly different from those in the patients without these autoantibodies. Furthermore, severe purpura and a poor response to prednisolone were far more common in the patients with anti-GPIb autoantibodies. Activation of the complement system and/or functional abnormalities of lymphocytes thus appear to be involved in the development of thrombocytopenia in ITP patients with anti-GPIb autoantibodies, and such antibodies may be associated with a particularly severe form of ITP.

Autoantibodies↗

PubMed1990

[Analysis of adhesive proteins on the surface membrane of platelet in malignant neoplasm].

Flow cytometry was used to detect fibrinogen (platelet associated fibrinogen: PAFbg) and fibronectin (PAFn) on the surface membrane of platelets in leukemia (9 cases), lung cancer (15 cases) and hepatoma (8 cases) patients (by one color analysis method), and simultaneously to investigate the binding of monoclonal anti-glycoprotein (GP) IIb/IIIa and anti-GP Ib antibodies (by two color analysis). All patient groups showed higher Fbg values than the normal control group, but no differences were found between patient groups. The values of Fbg and Fn showed a correlation, but the pattern of binding did not show a regular tendency in any patient group. There also was no significant correlation between Fbg values and the positive percentage of monoclonal anti-GPIIb/IIIa and anti-GPIb antibodies, and the binding of Fbg did not inhibit that of monoclonal antibody. The results suggest the following. 1. There are no differences in platelet activation in leukemia, lung cancer and hepatoma patients, and the degree of platelet activation is decided by the degree and the kind of stimulation. 2. The increase of both PAFbg and PAFn prove to the existence of activated platelet.

Blood Platelets↗

PubMed1990

[Chronic ITP with a remarkable response to vitamin C administration after splenectomy].

This report deals with a case of 23-year-old woman with chronic idiopathic thrombocytopenic purpura (ITP) showing a favorable response to vitamin C (VC) administration. She was treated with glucocorticoids and immunosuppressants, whereas inadequately controlled with its tolerable dosage. Next, she underwent splenectomy. However, there were only transient effects on platelet counts, so the therapy with ascorbate was carried out according to the report by Brox et al. The platelet counts increased to 20 x 10(4)/microliters after 4 months. Side effects of VC therapy did not occur.

Adult↗

PubMedDate not supplied

Characterization of a novel activation-specific antiplatelet monoclonal antibody.

We developed a murine monoclonal antibody (KmT-50) which binds to a protein expressed on the surface of human platelets after activation. KmT-50 is an immunoglobulin G1 monoclonal antibody that recognizes a 50-kD antigen localized in intracellular organelles and the open canalicular system of unstimulated platelets. After platelets were stimulated, the antigen was secreted via the surface-connected canalicular system and exposed on the platelet membrane. KmT-50 bound not only to human platelets, but also to rabbit and monkey platelets. This new antibody may be useful for experimental studies on thrombosis and hemostasis.

Animals↗