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Biomedical subjects

D Stahl

Publications and source records attributed to D Stahl.

At least 19 recordsLinked to original sources
PubMed2005

Warm autoimmune hemolytic anemia is an IgM-IgG immune complex disease.

Warm autoimmune hemolytic anemia (WAIHA) is characterized by polyclonal IgG autoantibodies binding to red blood cells (RBC). The characterization of the autoantigen in WAIHA has not yet led to definitive results, and the etiology of RBC autoantibodies remains unclear. An altered control of self-reactive IgG by autologous IgM has been proposed as the underlying mechanism of disease in WAIHA, suggesting that IgM-IgG immune complexes contribute to the pathophysiology of the disease. In the present study, we purified and characterized IgM from plasma of WAIHA patients and from healthy controls using FPLC-based protocols and optical biosensor technology, and investigated IgG present within the IgM fractions. We provide evidence that IgM-IgG immune complexes in plasma and associated with the RBC membrane are the characteristic feature of WAIHA, independent of the etiology of the disease. IgM-IgG immune complexes of WAIHA patients differ from IgM-IgG immune complexes of healthy individuals with regard to quantity and to structural composition. The data suggest that self-immunoglobulin is the original autoantigen underlying WAIHA. The molecular characterization of IgM-IgG immune complexes may define new targets for therapeutic intervention in WAIHA.

Adult↗
PubMed2005

Delineation of an interstitial 9q22 deletion in basal cell nevus syndrome.

Basal cell nevus syndrome (Gorlin syndrome) is an autosomal dominant disorder characterized by the presence of multiple basal cell carcinomas (BCC), odontogenic keratocysts, palmoplantar pits, and calcification in the falx cerebri caused by mutational inactivation of the PTCH gene. In few cases, the syndrome is due to a microdeletion at 9q22. Using high-resolution chromosome analysis we have identified a patient with the karyotype, 46,XY,del(9)(q21.3q31) de novo. He had typical clinical features consistent with basal cell nevus syndrome, but also additional features likely to be caused by loss of additional chromosomal material in this region. The deletion breakpoints were characterized with fluorescence in situ hybridization (FISH) analysis using BAC clones. The 15 Mb long deletion includes 87 RefSeq genes including PTCH. Hemizygosity of one or more genes might contribute to the additional symptoms observed in this patient.

Adult↗
PubMed2001

Reconstitution of self-reactive antibody repertoires of autologous plasma IgM in patients with non-Hodgkin's lymphoma following myeloablative therapy.

In healthy individuals, natural self-reactive antibody repertoires are restricted to a limited subset of autoantigens that is selected early in development and that remains invariant between individuals through aging. In the present study, we addressed the question of whether self-reactive antibody repertoires of plasma IgM change during high-dose chemotherapy (HDCT) with autologous blood stem cell support and whether antibody repertoires generated during immune reconstitution are similar to those present under physiological conditions. We followed the development of antibody repertoires in patients undergoing HDCT for the treatment of B-cell non-Hodgkin's lymphoma (NHL). Antibody repertoires were investigated by quantitative immunoblotting on whole tissue extracts as sources of self-antigens and by multiparametric statistical analysis of the data. We demonstrate that self-reactive antibody repertoires of plasma IgM of NHL patients prior to HDCT differ from those of healthy individuals, that they change during recovery of immune functions, and that antibody repertoires similar to those of healthy individuals are generated during immune reconstitution. We conclude that the mechanisms responsible for the selection of self-reactive repertoires of autologous plasma IgM during immune reconstitution after HDCT may follow those present under physiological conditions and that immune reconstitution may include a shift from altered toward normal patterns of self-reactivity.

Adult↗
PubMed2001

Altered self-reactive antibody repertoires are a general feature of patients with myelodysplastic syndrome.

Myelodysplastic syndrome (MDS) is characterized by an acquired clonal disorder of haematopoietic progenitor cells that results in inhibition of normal haematopoiesis and contributes to the development of haematological malignancies. Autoimmune syndromes may occur in MDS, but they are not a major clinical feature of the disease. In the present study, we have analysed the global antibody repertoires of IgM and IgG in plasma of 10 patients with MDS toward self- and non-self-antigens by quantitative immunoblotting. Myelodysplastic syndrome patients included in this study did not exhibit autoimmune symptoms nor secondary haematological neoplastic disease. Data were compared by means of multiparametric statistical analysis. We demonstrate that the antibody repertoires of self-reactive IgM and IgG of patients with MDS exhibit significantly altered patterns of reactivity, as compared to those of healthy individuals. In contrast, reactivity patterns of IgM in plasma of patients and of healthy controls toward non-self-antigens were similar, whereas reactivity patterns of IgG of patients and healthy subjects toward non-self-antigens were discriminated by multiparametric statistical analysis. These observations indicate that a broad disturbance of self-recognition mechanisms is a general feature of patients with MDS. A failure in the regulation of self-reactivity may contribute to the pathogenesis of MDS.

Adult↗
PubMed2001

Induction of natural autoantibody activity following treatment of human immunoglobulin with dissociating agents.

Treatment of normal polyclonal human IgG and of F(ab')2 fragments of IgG with 6.0 M urea, 1.3 M sodium thiocyanate or with acidic buffers (pH 2.0), resulted in a dramatic and selective enhancement of the preexisting antibody reactivity with self antigens. Enhanced antibody activity revealed by the dissociating agents was inhibited by the addition of an excess of the relevant soluble antigen. Human monoclonal IgG, including four different IgG1m(1) V(H)3+ and V(K)3+ paraproteins differing only in their CDRs, exhibited different changes in reactivity following urea treatment indicating major involvement of CDR sequences. The calculated dissociation constant of the binding reaction of normal IgG to the self antigen actin was 10(-6) M, whether IgG had been treated or not, indicating that the treatment increased the proportion of available self-reactive molecules instead of increasing the affinity of the preexisting natural autoantibodies. Enhanced autoreactivity was not due to aggregation of Ig, unmasking of the antibody site by removal of low MW antigens, nor to the denaturation of natural Id-anti-Id complexes. Taken together, these results suggest that treatment of Ig with dissociating agent results in the exposure of basic polyreactive antibody structures. The enhancement of reactivity may be of relevance in physiology of mucosal immunity and in therapeutic immunomodulation.

Actins↗
PubMed2001

Altered antibody repertoires of plasma IgM and IgG toward nonself antigens in patients with warm autoimmune hemolytic anemia.

Warm autoimmune hemolytic anemia (WAIHA) is characterized by an accelerated extravascular clearance of red blood cells (RBC) mediated by RBC-bound IgG autoantibodies. We have recently demonstrated significantly altered self-reactive antibody (Ab) repertoires of plasma IgM in WAIHA patients. The natural IgM Ab repertoire in plasma is critical in modulating both autoimmune and alloimmune responses. In the present study, we investigated IgM and IgG Ab repertoires of WAIHA patients toward nonself antigens (Ag) using a quantitative immunoblotting technique, followed by multiparametric statistical analysis of the data. We demonstrate significantly altered Ab repertoires of IgM and IgG toward nonself Ag in WAIHA patients. The reactivity of plasma IgM of WAIHA patients was reduced compared to that of healthy individuals, independent of administering an immunosuppressive therapy. We observed that an increase in reactivity of plasma IgM during clinical remission of the disease was associated with the development of allo-Ab toward RBC-antigens during RBC transfusions. Taken together, the data indicate altered Ab repertoires of plasma IgM and IgG toward nonself Ag in WAIHA patients. A broadly reduced reactivity of plasma IgM toward nonself Ag might influence the adaptive immune response in WAIHA patients.

Adult↗
PubMed2001

Idiopathic membranous glomerulonephritis is associated with altered patterns of self-reactive IgM and IgG antibody repertoires.

Idiopathic membranous glomerulonephritis (MGN) is an immune complex nephropathy characterized by the subepithelial deposition of immunoglobulin (Ig)G. The pathogenesis of the disease remains largely unknown, but recent evidence suggests that human MGN may involve an autoimmune component. In the present study, we have analyzed the IgM and IgG antibody repertoires of patients with MGN towards self- and nonself-antigens using a technique of quantitative immunoblotting on a panel of whole human tissue or solubilized bacterial cell extracts as sources of antigens. Data were compared by means of multiparametric statistical analysis. We demonstrate that the antibody repertoires of self-reactive IgM and IgG in plasma of patients with MGN exhibit significantly altered patterns of reactivity, as compared with those of healthy controls. In contrast, multiparametric statistical analysis does not discriminate the reactivity patterns of IgM and IgG in plasma of patients and healthy controls towards nonself antigens. These observations indicate that a failure in the regulation of physiological self-reactivity is associated with immune complex nephropathy in MGN.

Adult↗
PubMed2001

Broad alterations of self-reactive antibody-repertoires of plasma IgM and IgG in B-cell chronic lymphocytic leukemia (B-CLL) and B-CLL related target-restricted autoimmunity.

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by a malignant CD5+ B-cell clone. The leukemic clone commonly expresses IgM antibodies exhibiting reactivity toward a wide range of self-antigens. However, B-CLL associated autoimmunity is typically restricted to self-antigens expressed by blood cells, and mediated by IgG autoantibodies of polyclonal origin. In the present study, we addressed the question whether self-reactive antibody repertoires of plasma IgM and IgG are disturbed by monoclonal immunoglobulins of B-CLL patients, and whether antibody repertoires of patients exhibiting B-CLL associated target-restricted autoimmune disease (AID) differ from those of B-CLL patients without AID. We investigated antibody repertoires at a global level, using a technique of quantitative immunoblotting that allows for the quantitative screening of antibody reactivities in complex antibody mixtures toward a large panel of antigens derived from homologous tissue extracts, followed by multiparametric statistical analysis of the data. We demonstrate that self-reactive antibody repertoires of plasma IgM and IgG are broadly altered in patients with B-CLL, that alterations in self-reactive antibody repertoires are not restricted to B-CLL patients exhibiting AID, and that target-restricted autoimmunity in B-CLL patients is associated with altered antibody repertoires not restricted to the target organ. We conclude that monoclonal alterations of immunoglobulin production in B-CLL are associated with broad defects of self-reactive antibody repertoires. Our observations suggest that the application of therapeutic IVIg preparations might influence B-CLL by restoring normal self-reactive antibody repertoires in plasma.

Adult↗
PubMed2000

Analysis of human self-reactive antibody repertoires by quantitative immunoblotting.

We review the use of a quantitative immunoblotting technique to characterize human self-reactive antibody repertoires in health and disease. The interactions of plasma IgM and IgG with tissue extracts as sources of self-antigens were analyzed by quantitative immunoblotting. Data were compared by means of multiparametric statistical analysis. The data summarized here demonstrate that natural self-reactive antibody repertoires of healthy individuals are restricted to a limited subset of immunodominant autoantigens that is selected early in development, and remains conserved between individuals through ageing. The selection of human natural self-reactive IgG antibody repertoires requires normal T-/B-cell interactions. The immunoblotting assay has the potential to distinguish between autoimmune diseases with organ-related oligoclonal expansion of self-reactive clones and those characterized by broad alterations of immunoregulation. However, organ-specific autoimmune diseases may be characterized by altered patterns of antibody repertoires unrelated to the target organ. The assay also revealed an unexpected defect in the regulatory function of self-reactive IgM on the expression of self-reactive IgG repertoires in several systemic and organ-specific autoimmune diseases. The results are discussed in the light of our current understanding of the processes of selection of self-reactive B-cells and the pathophysiology of autoimmunity.

Autoantibodies↗
PubMed2000

Altered control of self-reactive IgG by autologous IgM in patients with warm autoimmune hemolytic anemia.

Warm autoimmune hemolytic anemia (WAIHA) is characterized by an accelerated clearance of red blood cells (RBCs) associated with the presence of anti-RBC immunoglobulin (Ig)G autoantibodies. In the present study, we analyzed the self-reactive IgG and IgM antibody repertoires of patients with WAIHA using a technique of quantitative immunoblotting on a panel of whole tissue extracts as sources of self-antigens. Data were compared by means of multiparametric statistical analysis. We demonstrate that self-reactive antibody repertoires of IgG purified from plasma and of IgG purified from RBC eluates do not differ between healthy donors and patients with WAIHA, whereas autoreactive repertoires of IgM from patients exhibit broadly altered patterns of reactivity as compared with those of healthy controls. We further demonstrate that IgG purified from eluates of RBCs of healthy donors induces agglutination of RBCs in an indirect Coombs assay to a similar extent as IgG purified from eluates of RBCs of patients with WAIHA. The capability of IgG to induce agglutination of RBCs is suppressed in unfractionated eluates of healthy donors' cells, whereas it is readily found in unfractionated eluates of patients' RBCs. IgM is an essential factor in controlling the ability of IgG in unfractionated RBC eluates to induce agglutination of RBCs. These observations indicate that anti-RBC IgG autoantibodies of patients with WAIHA share extensive similarity with natural antiRBC autoantibodies of healthy donors and suggest that defective control of IgG autoreactivity by autologous IgM is an underlying mechanism for autoimmune hemolysis in WAIHA. (Blood. 2000;95:328-335)

Adult↗
PubMed2000

Polyreactivity of disease-associated anti-RBC IgG autoantibodies of patients with warm autoimmune haemolytic anaemia and natural anti-RBC IgG autoantibodies of healthy individuals.

Anti-red blood cell (RBC) immunoglobulin G (IgG) autoantibodies are present in patients with warm autoimmune haemolytic anaemia (WAIHA), and, as natural autoantibodies, in healthy individuals. This study investigated whether the feature of polyreactivity discriminates disease-associated from natural anti-RBC IgG autoantibodies. The patterns of reactivity of purified anti-RBC IgG eluted from the RBC of WAIHA patients and from the RBC of healthy individuals were analysed using quantitative immunoblotting on a panel of whole human tissue or bacterial cell extracts as antigen sources. In parallel, the reactivity patterns of IgG purified from plasma were analysed. Anti-RBC IgG of WAIHA patients and of healthy individuals recognized a wide range of self- and nonself-antigens. The reactivity patterns of anti-RBC IgG were homogeneous among patients and controls, did not differ between patients and controls, and were similar to those of IgG purified from plasma in the case of both patients and healthy individuals. The data demonstrate that the anti-RBC IgG autoantibodies of WAIHA patients share extensive similarity with those of healthy individuals. Polyreactivity is a common feature of both disease-associated and natural anti-RBC IgG autoantibodies.

Aged↗
PubMed2000

Natural antibodies to factor VIII.

Anti-factor VIII antibodies represent a unique model to study the relationship between natural autoreactivity (natural antibodies to factor VIII of healthy individuals), disease-associated autoimmunity ("spontaneous" factor VIII inhibitors of patients with anti-factor VIII autoimmune disease) and antigen-driven immune responses (immune inhibitors in multitransfused patients with hemophilia A) to a single human protein antigen. Although natural and disease-associated anti-factor VIII antibodies are not readily distinguished based on the comparison of their isotypic distribution and epitope mapping, available studies of cross-reacting idiotypes suggest that factor VIII inhibitors in patient's plasma encompass two populations of anti-factor VIII antibodies. Some antibodies result from the clonal expansion of B lymphocytes that exist before treatment with factor VIII and secrete anti-factor VIII antibodies with properties similar to those of natural anti-factor VIII antibodies present in healthy individuals; other inhibitors are produced by B cell clones that have undergone affinity maturation and hypermutation of the V regions of the antibodies they produce. The implications for the treatment of patients with anti-factor VIII inhibitors are discussed.

Antibodies, Anti-Idiotypic↗
PubMed1999

Defective self-reactive antibody repertoire of serum IgM in patients with hyper-IgM syndrome.

We have analyzed the self-reactive repertoires of IgM and IgG Abs in the serum of 19 patients with hyper-IgM syndrome (HIM) by means of a quantitative immunoblotting technique that allows for a quantitative comparison of Ab repertoires in health and disease by multiparametric statistical analysis. Normal tissue extracts of liver, lung, stomach, and kidney were used as sources of self Ags. Extracts of Pseudomonas aeruginosa and Staphylococcus epidermidis were used as sources of nonself Ags. We demonstrate a significant bias in repertoires of reactivities of IgM of patients with HIM with self Ags. Ab repertoires of IgM toward nonself Ags did not differ, however, between patients and controls. No difference was found between IgM repertoires of untreated patients and those of patients receiving substitutive treatment with i.v. IgG. IgG in the serum of HIM patients lacked reactivity with self Ags, although it exhibited a pattern of reactivity with nonself Ags that was similar to that of IgG of healthy controls. The data demonstrate that functional CD40-CD40 ligand interactions are essential for the selection of natural self-reactive B cell repertoires.

Adolescent↗
PubMed1998

A case of mu heavy-chain disease associated with hyperglobulinemia, anemia, and a positive Coombs test.

We report here for the first time a patient with mu heavy-chain disease (HCD), hyperimmunoglobulinemia, and a positive direct antiglobulin test (DAT, Coombs test). The heavy-chain diseases involve the proliferation of lymphoplasma cells of B cell origin and are characterized by the production of incomplete heavy chains devoid of light chains. The association of mu heavy-chain disease with either hyperglobulinemia or a positive DAT has not been reported in the literature to date. In this patient, immunofixation of serum proteins with monospecific antisera to alpha-, gamma-, mu,- or delta-chains and to kappa- and lambda-chains revealed a precipitation band with antibody to IgM, but not with kappa and lambda light-chain antibodies, indicating mu heavy-chain disease. Hyperglobulinemia was present, which is very uncommon for HCD. A DAT of the patient's red blood cells (RBC) was found to be strongly positive for anti-IgG but negative for anti-IgM, -IgA, -C3c, and -C3d. However, when the eluate from the patient's red blood cells was investigated with nephelometry, it was found to contain antigens reactive with anti-y as well with anti-mu-antiserum. When a DAT was performed with a randomly chosen test cell incubated with the eluate, the antibody-containing eluate was shown to react with anti-IgG as well as with anti-IgM-antiserum. In summary, the eluate from the patient's RBCs contained IgG and an immunoglobulin structure reactive with anti-IgM in an RBC agglutination assay as well as with anti-mu antiserum in a nephelometric investigation. Whether this IgM on the patient's erythrocytes is penta- or oligomeric, complete IgM, or the heavy chain cannot be concluded from these observations.

Aged↗
PubMed1998

Serum affinity chromatography for the detection of IgG alloantibodies in a patient with high-titer IgM cold agglutinins.

BACKGROUND AND OBJECTIVES: High-titer cold autoagglutinins (CA) interfere with the detection of alloantibodies against red-blood-cell antigens. The diagnostic procedure is extremely difficult, especially under pressure of time. It was the purpose of the study to find out whether quantitative IgG purification from serum or plasma by affinity chromatography facilitates the detection of IgG alloantibodies in the presence of high-titer IgM CA. MATERIALS AND METHODS: Serum: IgM-chi CA, 0 degrees C titer = 65,000; five anti-IgG reactive alloantibodies. Affinity chromatography: HiTrap protein G 1-ml affinity column (Pharmacia Biotech, Uppsala, Sweden). RESULTS: All IgG alloantibodies were detectable in the eluate after affinity chromatography without interference of IgM CA. CONCLUSION: IgG alloantibodies in the presence of high-titer IgM CA can be easily and rapidly detected under routine conditions by quantitative IgG purification from serum or plasma by affinity chromatography.

Anemia, Hemolytic, Autoimmune↗
PubMed1997

Sensitization to d-amphetamine after its repeated administration: evidence in EEG and behaviour.

After repeated administration of cocaine or d-amphetamine, a sensitization to their behavioural effects is frequently observed instead of a tolerance. In a previous study, it was shown that a moderate dose of d-amphetamine produced a pattern of EEG power spectrum which indicated a selective activation of D1-like dopamine receptors, whereas a larger dose induced a selective increase of power in the alpha-1 frequency band and, to a lesser degree, in the alpha-2 band, suggesting an additional activation of D2-like receptors. Furthermore, it was recently found that under a certain dosage and schedule, cocaine could produce a shift from a D1-characteristic to a D2-like EEG pattern. It was now studied, if the same is true for d-amphetamine. This drug was administered on 4 subsequent days (0.6 mg/kg i.p.); after an interval of 3 days, the same dose was administered. After repeated, but not a single administration, increases in the power of the alpha-1 and alpha-2 frequency bands were observed, suggesting a shift from activation of D1-like to additional activation of D2-like receptors. This shift was accompanied by a slight enhancement in stereotyped behaviour (sniffing). After a lower dose (0.2 mg/kg), no EEG effect could be observed, neither after a single nor after repeated administration.

Animals↗
PubMed1997

Pulsed high-dose dexamethasone in chronic autoimmune haemolytic anaemia of warm type.

The management of patients with autoimmune haemolytic anaemia of warm type (AIHA) is often problematic. Recently, pulsed high-dose dexamethasone (HDD) has been shown to be effective in the treatment of autoimmune thrombocytopenic purpura (AITP). In this study we treated seven patients with AIHA with HDD. The regimen recommended for treatment of refractory AITP (40 mg dexamethasone for 4 d at the beginning of each 28 d cycle) was employed in almost all cases. Prior to dexamethasone administration, haemolysis was decompensated in all seven patients. HDD was well tolerated and led to an improvement of haemolysis in all cases.

Adult↗