Biomedical subjects

Y Kurata

Publications and source records attributed to Y Kurata.

At least 109 records · Page 6Linked to original sources

PubMed1994

Selective effects of alcohols on gamma-aminobutyric acid A receptor subunits expressed in human embryonic kidney cells.

Several previous studies implicated alpha 6 and gamma 2L subunits as potential determinants of gamma-aminobutyric acid A (GABAA) receptor channel sensitivity to alcohol modulation. The effects of ethanol and n-octanol were studied on GABA-induced currents in human embryonic kidney cells transfected to express one of three different GABAA receptor channel subunit combinations: alpha 1 beta 2 gamma 2S, alpha 6 beta 2 gamma 2S or alpha 6 beta 2 gamma 2L. No increase in the current amplitude of any subunit combination was observed after the coapplication of GABA and physiological concentrations (10-100 mM) of ethanol. By contrast, the coapplication of GABA and 100 microM octanol increased the current amplitude by 50% to 100% in all three subunit combinations. Octanol produced a shift of the current dose-response curve toward lower concentrations of GABA. Ethanol was effective in increasing the rate of desensitization produced by higher concentrations of GABA in the alpha 6 beta 2 gamma 2S cells but not the alpha 1 beta 2 gamma 2S combination. This ethanol-induced modification of desensitization was not altered by the presence of the protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). These experiments indicate that the presence of alpha 6 or gamma 2L subunits, in itself, does not result in the potentiation of GABA-induced currents by ethanol, as described in some reports. However, the presence of either the alpha 6 or alpha 1 subunit may determine whether the desensitization rate of the GABAA current is affected by the alcohol.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1994

[Detection of anti-neutrophil antibodies by enzyme linked immunosorbent assay--comparison of results obtained by ELISA with those by leukocyte agglutination test and granulocyte cytotoxicity test].

We examined anti-neutrophil antibodies in 12 patients with various disorders using enzyme-linked immunosorbent assay (ELISA), and the results obtained by ELISA were compared with those obtained by leukocyte agglutination test (LAT) and granulocyte cytotoxicity test (GCT). IgG anti-neutrophil antibody was positive in 7 of 12 patients, and IgM type antibody was positive in 6 patients. There was a significant correlation between IgG and IgM anti-neutrophil antibodies. The results obtained by ELISA were not in accord with those obtained by LAT or GCT. In addition, we examined anti-neutrophil antibodies in serially collected serum samples from two patients with immune neutropenia. The results obtained by ELISA correlated with their neutrophil counts, suggesting that anti-neutrophil antibodies detected by ELISA have pathological relevance.

Adult↗

PubMed1994

High-titer antinuclear antibodies, anti-SSA/Ro antibodies and anti-nuclear RNP antibodies in patients with idiopathic thrombocytopenic purpura.

The clinical significance of high-titer antinuclear antibodies (ANA) and autoantibodies to cellular antigens such as SSA/Ro and nuclear RNP (nRNP) antigens in idiopathic thrombocytopenic purpura (ITP) was examined in a prospective evaluation of 66 adult patients with chronic ITP. ANA were positive in 29 (44%) of 66 patients with chronic ITP. The titers of ANA were high (1:160 or higher) in 14 of 29 ANA-positive patients. Furthermore, 10 of 66 patients had precipitating antibodies to nuclear antigens; seven patients had anti-SSA/Ro antibodies and the other three had anti-nRNP antibodies. None of high-titer ANA- or precipitating antibody-positive patients developed systemic lupus erythematosus (SLE) throughout the follow-up period of 3 years. In addition, we investigated retrospectively precipitating antibodies in stocked sera from 8 patients. These patients had already precipitating antibodies average of 7.7 years before. None of 8 patients developed SLE or Sjogren's syndrome (SS). These data demonstrate that high-titer ANA and antibodies to SSA/Ro or nRNP antigens are often found in patients with ITP, and indicate that the detection of high-titer ANA or the existence of antibodies to SSA/Ro or nRNP antigens by itself is not enough to identify those patients with ITP who are at risk of developing SLE or SS.

Adult↗

PubMed1993

Alcohol modulation of cloned GABAA receptor-channel complex expressed in human kidney cell lines.

The effects of n-octanol on GABA-induced currents were examined on the alpha 1 beta 2 gamma 2s and alpha 1 beta 2 combinations of GABAA receptor subunits expressed in a human kidney cell line (HEK 293), using the whole-cell variation of the patch clamp technique. The EC50 of the GABA dose-response curve for the alpha 1 beta 2 combination was lower than that for the alpha 1 beta 2 gamma 2s combination. n-Octanol at 100 microM augmented the GABA-induced currents in a dose-dependent manner, decreasing the EC50 of the GABA dose-response curve without affecting the maximal response. The magnitude of n-octanol potentiation was nearly the same in both combinations. In contrast, a benzodiazepine agonist, chlordiazepoxide, augmented the currents of the alpha 1 beta 2 gamma 2s combination only. We conclude that the potentiation of GABAA receptor-mediated currents by a long carbon chain n-alcohol does not require the gamma 2 subunit.

1-Octanol↗

PubMed1993

Prevention and induction of occlusive coronary vascular disease in autoimmune (W/B)F1 mice by haploidentical bone marrow transplantation: possible role for anticardiolipin autoantibodies.

Male (NZW x BXSB)F1 (W/BF1) mice develop systemic autoimmunity involving autoantibodies, thrombocytopenia, lupus nephritis, and coronary vascular disease with myocardial infarction (CVD). To determine whether this murine lupus-associated CVD could be transferred to otherwise autoimmune-resistant (C57BL/6 x C3H/He)F1 (B6C3F1) mice via W/BF1 T-cell-depleted marrow (TCDM) transplants, or conversely whether the CVD of W/BF1 mice could be prevented by the reciprocal transplant, reciprocal haploidentical transplants of TCDM were performed. CVD developed only in mice with systemic autoimmunity. Mice that developed lupus had glomerulonephritis and thrombocytopenia and also had elevated titres of autoantibodies to double-strand DNA, cardiolipin, and platelets and elevated levels of circulating immune complexes. Of control W/BF1 mice, 80% developed lupus, and of these, 81% developed CVD with a mean grade of 2.5 +/- 0.8. Engraftment of W/BF1 mice with B6C3F1 marrow protected 90% of the recipients from the development of lupus, and none developed CVD. Engraftment of B6C3F1 mice with W/BF1 marrow induced lupus in 60% of the recipients, and of those, 33% developed CVD with a mean grade of 1.3 +/- 0.3. The B6C3F1 recipients of W/BF1 marrow which developed CVD had significantly higher titres of autoantibodies to cardiolipin (aCL; P < .01). These findings show that genetic abnormalities present in the W/BF1 hematopoietic stem cells contribute to autoantibody development, including aCL, and suggest that thrombogenic mechanisms induced by aCL may contribute to the development of CVD in this form of murine lupus erythematosus.

Animals↗

PubMed1993

Development and characterization of monoclonal antiplatelet autoantibodies from autoimmune thrombocytopenic purpura-prone (NZW x BXSB)F1 mice.

Male (NZW x BXSB)F1 (W/BF1) mice develop systemic autoimmunity involving autoantibodies, progressive thrombocytopenia, lupus nephritis, and degenerative coronary vascular disease with myocardial infarction. Platelet-associated IgG (PAIgG) on the platelet surface mediates platelet destruction by the reticuloendothelial system in the autoimmune thrombocytopenic purpura (ATP) of W/BF1 mice. Because the epitopes targeted in ATP by PAIgG have not been identifiable using serum from thrombocytopenic W/BF1 mice, we developed seven hybridomas secreting antiplatelet monoclonal antibodies (MoAbs) using splenocytes of thrombocytopenic W/BF1 mice. Epitopes recognized by three MoAbs were similar to those recognized by PAIgG, because eluted IgG from platelets of thrombocytopenic W/BF1 mice inhibited platelet binding by MoAbs in competitive micro-enzyme-linked immunosorbent assay. Hybridoma cells or purified Ig from the ascites of two clones (2A12 and 6A6), when injected into nude mice produced acute thrombocytopenia, elevated the levels of PAIgG, purpura, and megakaryocytosis. MoAbs of two clones also reacted with single-stranded DNA or double-stranded DNA, and one of these clones (4-13) bound to cardiolipin (CL) but was nonpathogenic in nude mice, suggesting that anti-CL and antiplatelet autoantibodies can be distinct. On immunoblotting analysis, antiplatelet MoAbs frequently bound a 100-Kd platelet protein. These MoAbs contribute to an understanding of the etiopathogenesis of ATP and the several antigens and autoantibodies involved.

Animals↗

PubMed1993

Alterations in populations of GST-p-immunoreactive single hepatocytes and hepatocellular foci after a single injection of N-nitrosodiethylamine with or without phenobarbital promotion in male F344/NCr rats.

The fate of placental glutathione S-transferase (GST-P)-immunoreactive hepatocytes, detectable in livers of rats soon after treatment with N-nitrosodiethylamine (DEN), was examined sequentially with or without phenobarbital (PB) promotion. Group 1 male F344/NCr rats were administered a single i.p. injection of 200 mg DEN per kg body weight at 5 weeks of age. Group 2 rats were given 500 ppm PB in the diet two weeks after the DEN treatment. Groups of six rats were sequentially sacrificed 16, 42, 70, 126 and 238 days after DEN injection. In DEN-treated rats, GST-P immunoreactive hepatocytes (single cells and multiple cell foci) were detectable 16 days after DEN, the total numbers decreasing by day 70 and thereafter rising again. In the early stages the proportion of single immunoreactive hepatocytes was prominent, but with time a gradual increase in small GST-P+ hepatocellular foci and larger foci became evident. Feeding of PB to rats for 16-238 days after a single DEN injection resulted in increases of both single cells and foci, especially foci composed of more than three hepatocytes. The growth response was increasingly pronounced with time. Adenomas or carcinomas were only observed at 126 or 238 days. Numbers of GST-P+ foci far exceeded the numbers of foci visible in hematoxylin-eosin (H & E) stained sections, and a few H & E foci were negative for GST-P. Many GST-P+ foci smaller than ten cells were composed of histologically normal hepatocytes. Almost all GST-P+ foci identifiable in H&E stained sections were larger than ten cells, consisted of clear cells (in both groups) or mixed (clear-eosinophilic) cells in PB-exposed rats, and appeared to be evenly distributed throughout the three zones of the liver. These results suggest that the promotive effect of PB is most evident as an increase in larger hepatocyte populations composed of more than three GST-P+ hepatocytes, rather than in increasing the populations of single GST-P immunoreactive cells. PB may cause clonal expansion of these single GST-P reactive hepatocytes. This study provides evidence for the hypothesis that some of the GST-P reactive hepatocytes are initiated cells.

Animals↗

PubMed1993

A novel polymorphism in glycoprotein IV (replacement of proline-90 by serine) predominates in subjects with platelet GPIV deficiency.

To clarify the molecular basis of the deficiency of glycoprotein IV (GPIV) of the platelet surface, we analyzed GPIV cDNA synthesized from platelet RNA of five unrelated Japanese subjects whose platelets did not express GPIV. We confirmed the presence of normal-sized GPIV mRNA in platelets from subjects with GPIV deficiency. The sequence of platelet GPIV cDNA from GPIV deficient subject showed three differences when compared with the published sequence; 1) a replacement of a 478CCT codon for proline-90 by TCT for serine, 2) a four-base insertion in the 3'-noncoding region, and 3) a substitution of A for 79C in the 5'-noncoding region. The replacement of Pro90 by Ser predominates in subjects with GPIV deficiency; that is, four out of five platelets with GPIV deficiency contained GPIV mRNA encoding GPIVSer-90, while all platelets from 17 GPIV positive subjects had GPIV mRNA encoding GPIVPro-90. The sequence of platelet GPIV cDNA which did not encode GPIVSer-90 from a subject with GPIV deficiency revealed no abnormality in the coding region. The four-base insertion in the 3'-noncoding region and the substitution of A for 79C in the 5'-noncoding region seems to be unrelated to the expression of GPIV. The substitution of Ser for Pro90 might alter the GPIV structure or impair GPIV biosynthesis, resulting in a lack of detectable GPIV. This hypothesis remains to be tested.

Amino Acid Sequence↗

PubMed1993

Induction of micronucleated erythrocytes by recombinant human erythropoietin.

Induction of micronucleated erythrocytes by a recombinant human erythropoietin (rhEPO) was examined using both in vitro and in vivo test systems. A small, significant and dose-related increase in the frequency of micronucleated polychromatic erythrocytes (MNPCE) in bone marrow of mice administered i.p. with 12,500-50,000 IU/kg rhEPO was induced at 48 h sampling time. A clear positive dose--response relationship and significant increase in the frequency of micronucleated reticulocytes (MNRET) in peripheral blood of mice administered i.p. with 400-50,000 IU/kg rhEPO was noted at 48, 72 and 96 h sampling times. Conversely, in bacterial reverse mutation tests, no noticeable increase of auxotrophic revertants was observed in Salmonella typhimurium, TA100, TA98, TA1535, TA1537, or Escherichia coli, WP2 uvrA-, by treatment with 188-6000 IU/plate of rhEPO, with or without S9 mix. Furthermore, rhEPO at 750-6000 IU/ml did not induce chromosomal aberrations in vitro in CHL cells or human peripheral blood lymphocytes in a direct method nor in a metabolic activation method. Moreover, chromosomal aberrations were not detected in bone marrow cells of CD-1 male mice, even at high rhEPO concentrations (100,000 IU/kg) in vivo. Consequently, it was concluded that errors in the process of enucleation or differentiation of the erythrocytes should be equally considered as possible mechanisms for the increased frequencies of MNPCE and MNRET alongside induction of DNA damage or errors in the process of DNA repair.

Animals↗

PubMed1993

Genotoxicity of genetic recombinant human erythropoietin in a novel test system.

The nude (athymic) mouse was used as a novel test system for the evaluation of genotoxicity of genetic recombinant human erythropoietin (rhEPO). A fibroblast cell line derived from the kidneys of baby hamsters, BHK-21, or a subclone of BHK-21 transfected with an expression vector containing the human EPO gene, named BXE cells, were implanted in nude mice. The concentration of EPO in the plasma of mice bearing BXE increased in relation to the increase in the weight of the tumor formed from growth of BXE cells. Increased values of hematocrit (Ht), ratio of reticulocytes to erythrocytes (RET ratio) and the number of red blood cells in mice bearing BXE indicated that excessive hematopoiesis was occurring in the host. However, the concentrations of EPO in the plasma of the mice bearing BHK-21 did not increase in relation to the cell mass and consequently the Ht values and RET ratios in these mice were not affected. Marked increases in the frequencies of micronucleated polychromatic erythrocytes (MNPCE) and micronucleated RET (MNRET) were noted in the mice bearing BXE, although no chromosomal aberrations were found in the spleen and marrow cells of the same mice. The increased levels of RET, MNRET and MNPCE seemed to result from acceleration of erythroblastic maturation and proliferation by rhEPO. It is, therefore, concluded that errors in the processes of enucleation or differentiation of erythrocytes should be equally considered as possible mechanisms alongside errors in genetic repair processes for the increased frequencies of MNPCE and MNRET.

Animals↗

PubMed1993

Comparative studies in induction of micronuclei by three genetically recombinant and urinary human erythropoietins.

Comparative studies on the induction of micronucleated erythrocytes by three recombinant human erythropoietins (rhEPOs) such as epoetin alpha, epoetin beta, and SNB-5001, and by urinary human EPO (uhEPO) were carried out in vivo. Small but significant increases in the frequency of micronucleated polychromatic erythrocytes (MNPCEs) in bone marrow of mice following a single intraperitoneal (i.p.) administration of each of the three rhEPOs and uhEPO (25,000 IU/kg) were observed at the 48 h sampling time. Clear, significant increases in the frequency of micronucleated reticulocytes (MNRETs) in the peripheral blood of mice similarly treated with the four hEPOs at 50,000 IU/kg were noted at the 48, 72 and 96 h sampling times. When mice were dosed with 50,000 IU/kg of each of the hEPOs once each day for 6 days and micronucleus preparations were made 24 h after the last administration, micronucleus induction in the bone marrow was not clearly demonstrated. As before, MNRETs in these mice were significantly induced in all cases. Consequently, it was concluded that induction of MNPCEs and MNRETs was a common characteristic of both native and genetically recombinant EPO.

Animals↗

PubMed1993

Influence of aging on multi-organ carcinogenesis in rats induced by N-methyl-N-nitrosourea.

The effects of aging on the multi-organ carcinogenesis induced in rats by N-methyl-N-nitrosourea (MNU), a direct carcinogen which does not need metabolic activation to exert carcinogenicity, were examined in male F344 rats. In the first experiment, rats at 6, 52, and 98 weeks of age were treated with MNU (20 mg/kg body weight, i.p.) twice weekly for 6 weeks and then maintained without any further treatment for 24 weeks in the case of young and middle-aged rats and for 18 weeks in the case of the old rats. In young rats, malignant lymphomas, particularly thymic types, were observed at significantly high incidence. A striking result in the middle-aged rats was the significantly higher incidence of adenocarcinomas in the small intestine than in young or old animals. The induction of proliferative and neoplastic lesions of the large intestine also tended to be increased in middle-aged rats. In addition, epithelial hyperplasia of the tongue, but not the forestomach, occurred at the highest incidence in the middle-aged group. There were no differences in the induction of epithelial lesions in the urinary bladder among the groups. In a second experiment, investigation of DNA synthesis in the tongue, small and large intestines, urinary bladder and lymph nodes did reveal significant increases or tendency for increase in the MNU-treated groups, but without differences with age. In contrast, the thymus of young rats showed significantly increased incorporation of BrdU label after administration of MNU, whereas it was markedly reduced in middle-aged rats. In a third experiment, O6-methyldeoxyguanine (O6-medG) DNA adduct formation was immunohistochemically detected in various organs including the thymus, forestomach, and small intestine without any differences with age. Thus, the results demonstrated that while the target organs of MNU are modified by the age of the animals, levels of DNA synthesis and O6-medG DNA adduct formation in most cases can not explain the observed differences in carcinogenic susceptibility.

Adenocarcinoma↗

PubMed1993

Elevated platelet-associated IgG in SLE patients due to anti-platelet autoantibody: differentiation between autoantibodies and immune complexes by ether elution.

The level of platelet-associated IgG (PAIgG) is reported to be elevated in patients with systemic lupus erythematosus (SLE). However, the nature of PAIgG is unclear. We have investigated whether the PAIgG of SLE consists of anti-platelet autoantibodies or immune complexes (IC). The PAIgG values measured by flow cytometry were elevated in 11/25 patients with SLE. 3/6 SLE patients with thrombocytopenia had a high level of PAIgG (the mean fluorescence intensity > 10). We used an ether elution technique to determine whether elevated PAIgG consists of anti-platelet antibodies or IC. Preliminary experiments showed that the eluates prepared from platelets sensitized with anti-HPA-4a antibody reacted with normal platelets, while the eluates prepared from platelets sensitized with heat-aggregated IgG or model IC failed to react with normal platelets. These results indicate that the reactivity of eluates can distinguish between platelet-bound antibody and IC. We applied this technique to analysis of the PAIgG of SLE platelets. The eluates from SLE platelets (the mean fluorescence intensity > 10) reacted with normal platelets, indicating that the PAIgG of SLE platelets has the nature of antiplatelet autoantibodies. Furthermore, we investigated the target antigens which bind PAIgGs of SLE, using the direct immunoprecipitation procedure and modified antigen capture ELISA (MACE). Both methods identified GPIIb/IIIa as the target antigens. We conclude that the ether elution technique can distinguish between anti-platelet antibodies and IC, and that the PAIgGs of SLE with a high PAIgG value and thrombocytopenia have the nature of anti-platelet autoantibodies.

Antigen-Antibody Complex↗

PubMed1993

Pathology of preneoplastic and neoplastic renal tubular lesions induced in F-344 rats by sodium barbital, a nongenotoxic renal carcinogen and nephrotoxin.

Sodium barbital (NaBB), a long-duration sedative/hypnotic barbiturate, is a nongenotoxic nephrotoxin and induces chronic persistent increases in rates of cell proliferation in renal cortical tubules of male F-344/NCr rats. In 5 of our 2-stage carcinogenesis experiments with NaBB at doses of 500, 1,000, or 4,000 ppm for periods of up to 106 wk of age, renal tubular cell tumors were found in incidences of up to 25% in rats receiving only NaBB while fewer than 1% of controls had renal epithelial tumors. We reviewed renal tubular proliferative lesions found in these studies and classified the lesions based on morphology, histogenesis, and immunohistochemical findings. Renal dysplastic tubules (DTs; atypical hyperplasia), putative preneoplastic lesions rarely seen in controls, were found in the renal cortex of more than 50% of the NaBB-exposed rats. DTs were classified into grades 1-3, based on lesion size and growth patterns. All renal adenomas were usually of the basophilic phenotype, and 70% of basophilic adenomas displayed solid patterns, while tumors with papillary, cystic, or tubular patterns were seen less commonly. By serial or step sectioning of the DTs and tumors, evidence was found indicating that the high grades (grade 2 or 3) of DTs, some of which arose in the P1 or P2 segment of the proximal tubules, were sometimes connected to the adenomas. Vimentin expression was demonstrated immunohistochemically in NaBB-induced renal tubular adenomas but not in normal tubules. Tumors were usually not immunoreactive for glutathione S-transferase, placental form, but heterogeneous immunoreactivity was also seen in some tumors. Lysozyme was absent in preneoplastic and neoplastic lesions induced by NaBB, while some intact normal proximal convoluted tubules were immunoreactive. The common tumor phenotype induced by NaBB, the basophilic solid adenoma, was similar to the most common type of spontaneous renal tumor found in untreated aging F-344 rats. NaBB may promote naturally occurring renal preneoplastic or neoplastic tubular lesions of this unique phenotype, but it is also possible that it may induce these lesions de novo.

Adenoma↗

PubMed1993

Cell proliferation not associated with carcinogenesis in rodents and humans.

Cell proliferation has often been found to be associated with carcinogenesis in rodents and humans at different stages of the multistage carcinogenesis process. The multistage process includes initiation, promotion, and progression phases. At each phase, increasing the normal level of cell turnover of target cells may enhance carcinogenesis. However, we present evidence that normal levels of cell turnover, or increasing the rate of cell turnover at these different stages, do not necessarily lead to enhanced carcinogenesis. In normal tissues, the length of the cell cycle depends on the age of the host and varies from tissue to tissue. Tissues with normal short cell cycles, such as intestine and bone marrow, do not show a high rate of spontaneous tumors in most species. Cells with higher turnover should be more susceptible to carcinogens at the initiation stage of carcinogenesis if cell proliferation per se causes cancer and if these cells or their progeny survive. Cancer in humans is more often associated with specific etiological factors rather than with the natural proliferative rate of specific tissues. For many tissues of humans and rodents, age-related diseases develop in a progressive, irreversible manner. Often, naturally occurring chronic degenerative and inflammatory changes in a tissue (e.g., kidney, liver, heart, reproductive tract) lead to chronic regeneration of the damaged tissue. Yet, cancer is rarely found in these tissues. In rodent carcinogenesis experiments, chronic toxic lesions, accompanied by increases in normal levels of cell turnover, have sometimes been observed in target organs of nongenotoxic carcinogens. More often, however, organ-specific nongenotoxic toxins are not carcinogens. These toxins include compounds toxic for the liver, kidney, and nasal cavity. In 19 inhalation bioassays conducted by the National Toxicology Program, 5/5 nasal carcinogens and 12/14 nasal noncarcinogens caused nasal lesions usually associated with chronic cell proliferation. Although cell proliferation may contribute to multistage carcinogenesis, cell proliferation is not necessarily a tumor promoter or cocarcinogen.

Aging↗

PubMed1993

Presence of the entire coding region of GP IV mRNA in Nak(a)-negative platelets.

It has been reported that Nak(a)-negative platelets lack GP IV. To examine the GP IV genetic defects in Nak(a)-negative platelets, we studied four unrelated Nak(a)-negative subjects by amplifying their GP IV cDNA, which were synthesized from platelet mRNA using the reverse transcriptase/polymerase chain reaction (RT/PCR). We detected the entire coding region of GP IV mRNA in the platelets of all four subjects. Restriction enzyme analysis of the amplified GP IV cDNA showed fully predictable cutting sites. These results suggest that no gross deletion or insertion had occurred in the GP IV mRNA of Nak(a)-negative platelets.

Antigens, CD↗

PubMed1993

[Anti-platelet antibodies in patients with autoimmune disorders].

The levels of platelet-associated IgG (PAIgG) are reported to be elevated in patients with systemic lupus erythematosus (SLE). However, the nature of PAIgG is unclear. We investigated whether PAIgGs of SLE are anti-platelet autoantibodies or immune complexes (IC). PAIgG levels measured by flow cytometry in patients with SLE (n = 25) were 12.7 +/- 41.0 (expressed by mean channel), slightly high (but not significant) compared with healthy subjects (2.5 +/- 0.7). Three of 6 SLE patients with thrombocytopenia had high level of PAIgG (mean channels > 10). To determine whether elevated PAIgGs are composed of anti-platelet antibody or IC, we applied elution technique. Preliminary experiments showed that the eluate prepared form platelets sensitized with anti-HPA-4a antibody reacted with normal platelets, while the eluates prepared from platelets sensitized both with heat aggregated IgG and with model IC did not react with normal platelets. These results indicated that the reactivity of eluates could discriminate between platelet-bound antibody and IC. We applied this method for the analyses of PAIgG of SLE platelets. The eluates from SLE platelets (mean channels were more than 10) reacted with normal platelets, indicating that PAIgGs of SLE platelets are anti-platelet autoantibody, not IC. Furthermore, we investigated the target antigens which bound PAIgGs of SLE, using the direct immunoprecipitation and modified antigen capture ELISA (MACE). Both methods identified GPIIb/IIIa as target antigens. We concluded that 1) ether elution technique could differentiate between anti-platelet antibody and IC, 2) PAIgGs of SLE had a nature of anti-platelet autoantibody, 3) the target antigens of PAIgG were GPIIb/IIIa.

Antigen-Antibody Complex↗

PubMed1993

[Pathogenic relevance of platelet-associated autoantibodies in chronic ITP--studies before and after splenectomy in three patients with chronic ITP by direct immunoprecipitation procedure].

This study was designed to investigate the pathogenic relevance of platelet-associated autoantibodies in chronic ITP, since the titer of platelet-associated autoantibodies does not appear to correlate with the severity of the disease. Employing a direct immunoprecipitation procedure, we examined platelets from three ITP patients with platelet-associated autoantibodies against GPIIb-IIIa and an unidentified 56 kD protein before and after splenectomy. In two patients, platelet-associated autoantibodies disappeared after splenectomy, and these two patients attained complete remission. In one patient, however, the amount of platelet-associated autoantibodies did not decrease after splenectomy. Although this patient's platelet count transiently increased to 500 x 10(3)/microliters after splenectomy, it decreased to 55 x 10(3)/microliters within a short time. These findings suggest that platelet-associated autoantibodies play a key role in platelet destruction in chronic ITP.

Adult↗