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Biomedical subjects

C P Engelfriet

Publications and source records attributed to C P Engelfriet.

At least 109 records · Page 6Linked to original sources
PubMed1981

Elution of blood group antibodies from red cells.

By slowly lowering the surface tension of the aqueous medium through the admixture of 47.5% dimethyl sulfoxide (DMSO) and 0.1% bovine serum albumin (BSA) and by raising the pH to 9, complete elution of A, D, and K antibodies from sensitized erythrocytes (RBC) could be achieved. The eluates comprising the antibodies were subjected to dialysis to remove the DMSO and to neutralize the pH, and to ultrafiltration to remove the excess water. Recovery of a sizeable proportion of the eluted RBC (of blood groups A and K) proved possible by slow and careful removal of the DMSO with phosphate-buffered saline containing 2% BSA.

Antibodies↗
PubMed1981

Idiopathic thrombocytopenic purpura in children; detection of platelet autoantibodies by immunofluorescence.

There are 3 varieties of idiopathic thrombocytopenic purpura (ITP) in children: the acute, the chronic and the recurrent forms. We have tested the platelets from 80 children with these forms of ITP by an immunofluorescence test. Platelet-bound immunoglobulins were detected in 19/22 acute, 41/48 chronic and 5/10 recurrent cases of ITP, i.e. in 65 of a total of 80 cases. A significance differences between acute and chronic ITP was found in the observation that only IgM was bound to the platelets of 7/16 patients with acute ITP. In all cases of chronic ITP with a positive direct immunofluorescence test, IgG was present on the platelet membrane. It is assumed because some patients with chronic ITP do not have elevated platelet-bound immunoglobulins, and show refractoriness to immunosuppressive therapy, that in these patients the disorder is not of a humoral autoimmune nature.

Adolescent↗
PubMed1981

Absence of platelet-specific alloantigens in Glanzmann's thrombasthenia.

The platelets of 11 patients with Glanzmann's thrombasthenia and their nearest family members were studied for the expression of the platelet-specific alloantigens of the Zw-, Ko- and Bak systems. The strength of the expression of the Zwa antigen was diminished on the platelets of 3 patients, and the antigen was absent from the platelets of the other 8. The platelets of none of the patients reacted with anti-Zwb serum. Therefore, Glanzmann's thrombasthenia is probably a "Zw-null disease." The expression of the Zwa antigen on the platelets of all the relatives was normal, as indicated on the cytoflurograph. Investigations on the expression of the Koa antigen were complicated by agglutinations of the platelets from genetically Koa-negative thrombasthenic patients with the anti-Koa serum. The Kob antigen was normally expressed. The Baka antigen was absent from the platelets of all thrombasthenic patients and a relatively high percentage of the relatives. A close association between the Glanzmann gene and the Bak(a-) gene is assumed on statistical grounds. Thrombasthenic platelets showed no reaction with EDTA-dependent antibodies, which are reactive with all normal platelets. Owing to immunization by multiple blood and platelet transfusions, serum samples of most patients studied contained HLA antibodies and platelet-specific alloantibodies. However, antibodies directed against the Zw-antigen-bearing glycoproteins were detected in the serum of only one patient and, therefore, seem to be rare.

Absorption↗
PubMed1981

Neonatal alloimmune thrombocytopenia: detection and characterization of the responsible antibodies by the platelet immunofluorescence test.

Platelet immunofluorescence, together with other serologic tests on platelets, lymphocytes, and granulocytes, was used to investigate the sera of 38 mothers with newborns who suffered from thrombocytopenia. In sera of 33 mothers, platelet-specific IgG alloantibodies were demonstrable. Three sera also contained HLA antibodies, of which two were only detectable in the lymphocyte cytotoxicity test. Two other sera contained granulocyte-specific alloantibodies. In sera of 2 mothers, antibodies were found that reacted with all cell types in all tests. However, after further analysis, it became clear that platelet-specific alloantibodies were probably also present in these 2 sera. In 29 cases, the specificity of the platelet alloantibodies was anti-Zwa--PlA1. One serum contained antibodies directed against a new antigen, Baka. This new antigen was defined after the investigation of the family and a small-scale population study. Two other sera had platelet antibodies with still undefined specificities. In all positive sera, IgG platelet alloantibodies were detected, and sometimes IgM antibodies were also present. The IgG antibodies were mostly of the IgG1 subclasses, but sometimes IgG3 and/or IgG4 was also found. In a few sera, only IgG3 antibodies were detected. In our series, we found no increased frequency of blood group ABO compatibility between mother and child, although it has been described by others and is well known to occur in rhesus alloimmunization. Of all the tests used, the platelet immunofluorescent test, especially the test on paraformaldehyde-fixed platelets in suspension, gave the best results in the detection of platelet antibodies in neonatal alloimmune thrombocytopenia.

ABO Blood-Group System↗
PubMed1980

Quantitative aspects of the destruction of red cells sensitized with IgG1 autoantibodies: an application of flow cytofluorometry.

The purpose of this study was to determine whether quantitative or qualitative factors are of major importance in the destruction of red cells sensitized with incomplete warm autoantibodies of subclass IgG1. To that end, the relative amount of igG1 antibody present on the red cells of patients with autoantibodies of this subclass only, was measured by means of continuous flow cytofluorometry. This method appeared to give an idea of the amount of antibody on red cells and was reproducible. The intensity of the fluorescence of patient's red cells, measured after incubation with a FITC-labelled anti-IgG1, was compared with the presence or absence of signs of increased haemolysis in vivo and the cytotoxic activity of normal monocytes towards these red cells in vitro. It appearedthat it was predominantly the amount of IgG1 autoantibody that determined whether or not these antibodies induced haemolysis in vivo or cytotoxicity of monocytes in vitro. This was also true with methyldopa-induced IgG1 autoantibodies.

Autoantibodies↗
PubMed1980

Detection of platelet antibodies: a comparison of three techniques.

For the detection of auto-antibodies on the platelets and in the serum of patients with idiopathic thrombocytopenic purpura, three new techniques have recently been developed: the quantitative antiglobulin consumption assay (QACA), the platelet radioactive antiglobulin test (PRAT) and the platelet suspension immunofluorescence test (PSIFT). The results obtained by various investigators with these techniques differ considerably. We, therefore, studied the sensitivity of the three methods. This was done by testing platelet-reactive allo-antibodies (anti-Zwa, anti-HLA-A2) and auto-antibodies in titration. The results show that the PSIFT is the most sensitive technique, closely followed by the PRAT. The QACA was found to be much less sensitive than the other two methods. This suggests that a positive result in the QACA and a negative result in the PSIFT and/or PRAT cannot be attributed to the presence of platelet auto-antibodies.

Autoantibodies↗
PubMed1980

Baka, a new platelet-specific antigen involved in neonatal allo-immune thrombocytopenia.

A family is described in which the mother developed platelet-specific antibodies, not directed against the antigens of the Zw(PlA) or the Ko system. The antibodies were only detectable in the immumofluorescence test and the radioactive antiglobulin test on platelets, and proved to be mainly IgG1 antibodies, although weak IgM antibodies of the same specificity were also detected. By cross-absorption studies, investigation of the family and a small-scale population study, it appeared that the antibodies were directed against a new antigen which we have called Baka. The frequency of the Baka phenotype in the Dutch population was 90.76%, the calculated genotype frequency 0.696. The Baka phenotype was neither sex-linked nor, so far as evaluable, closely linked to other platelet, red-cell, granulocyte, or HLA groups. The first child of this mother died of neonatal thrombocytopenia, the second child was unaffected. During the second pregnancy, the titre of the antibodies did not rise. The platelets of this child were found not to carry the Baka antigen.

Antibody Formation↗
PubMed1979

Granulocyte-specific alloantigen loss in chronic granulocytic leukaemia.

The granulocytes of 23 patients with chronic granulocytic leukaemia were examined in the indirect immunofluorescence test and some also in the microleucoagglutination test, with specific alloantisera against the NA1, NA2, NB1 and ND1 antigens and a specific granulocyte xenoantiserum. In 10 cases a complete loss of alloantigens was detected. In one patient a partial loss was found. A significant correlation was established between this loss and an accelerated activity (impending blast crisis) of the disease.

Epitopes↗
PubMed1979

Detection of B-cell-specific alloantibodies in pregnancy sera in the lymphocytotoxicity and the indirect immunofluorescence techniques.

Two hundred and eight pregnancy sera were tested for the presence of antibodies specific for lymphocyte sub-populations by using the isolated B and T lymphocytes from the women's mating partners. This was done by the microlymphocytotoxicity and the indirect immunofluorescence techniques. Five sera (2.5%) reacted exclusively with B lymphocytes and sixty-three sera (30.2%) reacted with both B and T lymphocytes; none of the sera was specific for T cells. Several sera, reacting with both B and T lymphocytes, were absorbed with platelets and this procedure revealed nine additional antiseraa specific for B lymphocyte antigens. Specificity studies on a panel of forty-eight HLA-ABCD typed individuals indicated that most antisera possibly defined new B-cell antigens. Family studies established that the antigens defined by these antiser were coded for by genes in the Major Histocompatibility Complex.

Antibody Specificity↗