Biomedical subjects

D Roelcke

Publications and source records attributed to D Roelcke.

At least 37 records · Page 2Linked to original sources

PubMed1995

Anti-Pr cold agglutinins recognize immunodominant alpha 2,3- or alpha 2,6-sialyl groups on glycophorins.

Anti-Pr agglutinins (CAs) with the subspecificities anti-Pr1h, -Pr1d, -Pr2, -Pr3h, -Pr3d, -PrM and anti-Sa CAs recognize immunodominant N-acetylneuraminic acid (NeuN Ac) groups of tetra and/or trisaccharides (O-glycans) of glycophorin. These O-glycans are sialylated in alpha 2,3- and/or alpha 2,6-linkages. Sa and most Pr antigens have been inactivated by alpha 2,3-specific sialidases. Antigenicity was reconstituted on desialylated glycophorin by alpha 2,3-specific Gal beta 1,3GalN Ac-sialyltransferase indicating that alpha 2,3-linked NeuN Ac groups are the immunodominant components of Sa and most Pr antigens. Some Pr antigens were resistant to alpha 2,3-specific sialidase and were not reconstituted by alpha 2,3-specific Gal beta 1,3GalN Ac-sialyltransferase, which indicates that alpha 2,6-linked NeuN Ac group represents an immunodominant component of some Pr antigens.

Adult↗

PubMed1995

Anti-adhesive glycosylation of fibronectin-like molecules in human placental matrix-type fibrinoid.

Recently, fibrinoid of the human placenta has been described as being composed of two main types differing in origin and chemical composition. Fibrin-type fibrinoid is mostly a blood clot product. Matrix-type fibrinoid was defined as the extracellular matrix secreted by extravillous trophoblast cells. The structure and composition of matrix-type fibrinoid was addressed in this study, focusing on fibronectins as one major constituent. A panel of antibodies directed against different fibronectin isoforms generated by different mRNA splicing, as well as antibodies recognizing oncofetal carbohydrate epitopes, were used on cryostat, paraffin and Lowicryl sections of placental tissue from different stages of pregnancy. The oncofetal carbohydrate epitopes studied comprised the blood group precursor antigens i and I. We identified the blood group-related antigen i as an additional marker for matrix-type fibrinoid. The antigen was detected on a glycoprotein that was also recognized by the fibronectin antibodies in western blots. Immunohistochemically this i-glycosylated oncofetal fibronectin-like molecule of about 55 kDa is expressed only by the invasive phenotype of extravillous trophoblast. Long chain carbohydrate moieties with a structure fulfilling the criteria for i reactivity on human placental fibronectin are known to have antiadhesive properties and to enhance resistance of the protein chain to proteolysis. These properties underline the functional relevance of glycosylation of fibronectins in matrix-type fibrinoid and suggest matrix-type fibrinoid is a typical matrix of invasive cells. In contrast, the more mature blood group precursor I could be detected after sialidase pretreatment of sections. This antigen was expressed by villous, non-invasive trophoblast.

Blotting, Western↗

PubMed1995

The immunoglobulin VH gene, VH4-21, specifically encodes autoanti-red cell antibodies against the I or i antigens.

Most autoanti-red cell antibodies found in patients with cold agglutinin disease are specific for the I or i carbohydrate antigenic determinants. However, antibodies specific for other antigens such as Pr or Sa can also be found, and these are identified by their pattern of reactivity with enzyme-treated red cells. Recently, it has been shown that the vast majority of anti-Ii antibodies react with a monoclonal anti-idiotypic antibody (9G4); this reactivity arises from restriction of the immunoglobulin heavy chains used to encode the antibodies to a single VH4-21 gene, VH4-21. The 9G4 antibody appears specific for this gene product, and we have used it to analyse VH4-21 gene involvement in encoding a spectrum of red cell antibodies of various specificities. The results support the strong association between usage of this gene and anti-Ii specificity and indicate that it is not generally used by other specificities. In particular, it is striking that the unsubstituted type 2 oligosaccharide antigens (I and i) induce a highly restricted autoantibody response very different from that induced by the sialylated type 2 antigens (Sia-b, -1 and 1b). The 9G4 antibody therefore provides a simple tool for discrimination between these autoanti-red cell antibodies, which should be of use in red cell serology.

Adult↗

PubMed1995

[Establishing a quality assurance system in transfusion medicine exemplified by the Heidelberg University Blood Bank].

BACKGROUND: The 'Zweite Verordnung zur Anderung der Betriebsverordnung für pharmazeutische Unternehmer vom 13. Juli 1994' requires a quality assurance system for the manufacturing of blood products. METHODS: On the basis of national law and guidelines we worked out a concept for establishing a quality assurance system at a university blood bank and applied it to the university blood bank at Heidelberg. RESULTS: The quality assurance system of the university blood bank at Heidelberg is based on the components 'quality of structure', 'quality of process' and 'quality of result'. The internal standard is specified in written form for every aspect of structure, process and result by standard operating procedures (SOP). The SOP serve as a basis for the quality system manual and the laboratory reference books. The quality assurance system described here integrates a programme for carrying out internal quality audits as well as a concept for updating SOP at regular intervals. CONCLUSIONS: The concept underlying the quality assurance system of the university blood bank at Heidelberg allows continuous quality improvement in transfusion medicine; moreover, it offers the chance to integrate quality assurance in transfusion medicine in an interdisciplinary, patient-orientated, not only regional concept of quality assurance.

Blood Banks↗

PubMed1994

Characterization of a monoclonal IgMK (IgMGAS) anti-Gd cold agglutinin (CA). Its coexistence with a monoclonal IgG3K (IgGGAS) without CA activity that might be clonally related to IgMGAS.

A monoclonal IgMK (IgMGAS) cold agglutinin (CA) of the infrequent anti-Gd specificity, found in a patient with Waldenström macroglobulinemia, has been characterized. IgMGAS uses a VH gene homologous (93.7%) to the reported VH251 germ-line, one of the two functional genes of the VH5 family, with differences in both framework regions and complementary determining regions (CDR). The VL gene is homologous to the reported 15AVK1 germ-line gene, recently described in an anti-i CA, with differences mostly clustered in CDR. In the patient's serum, IgMGAS coexisted with a monoclonal IgG3K (IgGGAS) that lacked CA activity but expressed the private idiotopes found on IgMGAS. Both Ig lacked reactivity with antibodies detecting VH1 or VHIII or VKIII subgroup regions or the VH4-21 gene product that is expressed by anti-I/i CAs. The K chains from both Igs showed the same isoelectrical mobility. Moreover, the k chains from both serum Igs showed the same N-terminal amino acid sequence. This sequence was identical to that predicted by the nucleotide sequence of VK1GAS gene segment, including one discrepancy at position 15 (Ile for Val) with respect to the consensus VK1 subgroup regions. Although these data do not exclude a possible independent clonal origin, they are consistent with the notion that IgGGAS might be clonally related to IgMGAS.

Aged↗

PubMed1994

Polylactosamine sugar chains expressed by epithelia of Henle's loop and collecting duct in rat and human kidney are selectively recognized by human cold agglutinins anti-I/i.

Normal rat and human kidney was mapped immunohistochemically with human monoclonal cold agglutinins against the biochemically related erythrocyte glycoconjugate antigens I and i, which represent branched and linear polylactosamines, respectively. The antibodies worked well with both cryostat and paraffin-embedded material. Anti-i gave specific staining of collecting duct cells (mostly principal cells) as evidenced by double labelling with antibodies to band 3 and a 23 kD protein of intercalated cells. In contrast, anti-I turned out to be the first exclusive marker for the ascending and descending thin limb of Henle's loop. In addition, in rat kidney, the binding of anti-I/i was preserved in primary cultures both of principal cells of the papillary collecting duct and cells of the thin limb of Henle's loop. Our results suggest that both antibodies might be interesting tools for in vitro studies of renal cell physiology and the investigation of kidney development.

Agglutinins↗

PubMed1994

Anti-j: human cold agglutinins recognizing linear (i) and branched (I) type 2 chains.

Two IgM lambda cold agglutinins (CAs) reacted with protease- and sialidase-resistant antigens expressed in equal strength on human adult (I), newborn (i), i adult, rabbit (I) and rhesus monkey (i) erythrocytes. The antibodies were inhibited by the linear type 2 sequence lacto-N-neotetraose and the branched type 2 sequence lacto-N-neohexaose. Endo-beta-galactosidase treatment of red cells, which splits type 2 chains from the surface, abolished CA reactivity. The CAs expressed the idiotype recognized by the anti-idiotype 9G4 specific for anti-I and anti-i CAs. The data suggest that the two CAs recognize linear (i) as well as branched (I) type 2 chains. It is proposed to term these CAs anti-j.

Aged↗

PubMed1994

Monoclonal IgM cold agglutinins with anti-Pr1d specificity in a patient with peripheral neuropathy.

A patient with a demyelinating sensory motor polyneuropathy secondary to IgM paraproteinaemia is reported. The paraprotein binds to the gangliosides GD1b, GT1b, GQ1b and GD3, all of which contain disialosyl groups with the sequence NeuAc alpha 2-8NeuAc alpha 2-3Gal. The paraprotein also acts as a cold agglutinin recognising the sialic-acid-dependent Pr1d antigenic determinant of the red cell membrane glycophorins. In this and in similar cases that have been reported, the coexistence of anti-Pr cold agglutinins and peripheral neuropathy suggest that they might be the causative agents of the disease.

Agglutinins↗

PubMed1994

Activation of complement by cold agglutinins.

OBJECTIVE: To review recent reports on the interaction of cold agglutinins with the complement system and its relevance to cold agglutinin disease. DATA SOURCES: Review articles and original papers have been selected for this contribution. SELECTION CRITERIA: The report focuses on experimental data available from in vitro studies as well as clinical findings regarding the mechanisms of cold agglutinin-induced complement activation. RESULTS: Despite the observation that only few cold agglutinins (almost exclusively IgM molecules with anti-I specificity) induce in vitro hemolysis of human red blood cells with human serum (homologous system), the vast majority of these autoantibodies are able to initiate the classical pathway sequence with the fixation of C1 and to a lesser degree of C4. The ability of IgM cold agglutinins to activate, in principle, complement is demonstrated by their hemolytic efficiency in the presence of animal serum as a source of heterologous complement. In addition to the thermal amplitude of cold agglutinin binding, a possible interference with membrane regulatory proteins may render certain cold agglutinins hemolytically active in a homologous system. CONCLUSION: Despite a hemolytic inefficiency, cold agglutinin-induced fixation of early complement components up to C3 leads to an accelerated clearance of red cells from the circulation by hepatic sequestration. However, it is not yet clear, to what degree these cells are eliminated by the reticuloendothelial system or whether they return to the circulation. Dependent on the amount of membrane-bound C3 fragments these cells may even be protected against further cold agglutinin-induced complement attack.

Agglutinins↗

PubMed1994

Red cell destruction in cold agglutinin disease.

OBJECTIVE: The severity of autoimmune hemolytic anemia (AIHA) caused by cold agglutinins (CAs) is known to differ markedly in chronic CA disease as well as in postinfection cold agglutination. The various cold agglutinin specificities and mechanisms of red cell destruction are described. DATA SOURCES: Original papers and reviews of the German and English literature (Medline research); own results. SELECTION CRITERIA: Original papers and reviews of the recent years on studies of the biochemistry and specificity of CAs and the pathophysiology of AIHA. RESULTS: A crucial point for the severity of AIHA caused by CAs is the CA-binding capacity to red cells in vivo. This is reflected by the serologic behavior of the actual CA in vitro, represented by its thermal amplitude. Because most CAs are IgM molecules, red cell destruction by CAs is limited to mechanisms initiated by complement (C) activation. In recent years, several CA specificities, in addition to anti-I/i, have been identified on a serological and biochemical basis. CAs of the IgG and rarely of the IgA isotypes have been found. CONCLUSION: The CA-induced red cell destruction does not only depend on CA titer or its thermal amplitude. The severity of CA-induced AIHA may also depend on CA isotype and/or specificity. Therefore, the complement activation capacity of CAs with a given isotype but different specificities has to be elucidated in further studies.

Agglutinins↗

PubMed1994

Immunoglobulin high-dose therapy: RBC-alloantibodies in commercial preparations and haemolytic anaemia: a case report.

A 4-year-old girl with idiopathic thrombocytopenia, who received immunoglobulin (Ig) in high dosage, developed haemolytic anaemia. Incompatible alloantibodies but no autoantibodies were found in her blood. In vitro the Ig preparation led to a strong fixation of alloantibodies and C3 on the girl's RBCs. Because of these reactions we investigated 12 Ig preparations and found irregular alloantibodies in 7 of them. The guidelines for quality assurance and other possibilities for lowering side reactions are discussed.

Anemia, Hemolytic↗

PubMed1994

[Cold agglutinins with new specificity against type 2 chains].

Two examples of IgM lambda cold agglutinins (CA) with a new specificity are characterized. 1. CAs ZI and BR react with newborn as well as with adult red cells. 2. Both CAs react with I- and i-active animal red cells. 3. The CAs are inhibited by linear and branched type 2 chains. 4. Endo-beta-galactosidase, splitting type 2 chains from human red cells, abolishes reactivity of both CAs. Both CAs recognize linear as well as branched type 2 chains.

Adult↗

PubMed1994

[Increase of post-infection cold agglutinins after infection with Mycoplasma pneumoniae, varicella-zoster and rubella virus].

Cold agglutinins (CA) are observed during acute infections as transiently occurring postinfection autoantibodies directed against erythrocyte antigens. Distinct infectious agents induce CA of distinct specificity. A common association is the infection with Mycoplasma pneumoniae and the production of CA with anti-I specificity. In infections with varicella-zoster virus (VZV) and rubella virus (RV) a few cases of CA appearance are reported, all of them showing specificity for the Pr antigens. We examined the frequency of CA with the anti-Pr specificity in patients suffering from acute infections with VZV and RV (table 1). The known association of anti-I in about 70% of the cases with acute Mycoplasma pneumoniae infection is confirmed by our results. The occurrence of CA in infections with VZV and RV is a rare event. Based on published data, the specificity of these CA apparently is anti-Pr. Three of 5 anti-Pr examples were found in newborns with rubella embryopathy. Possibly, anti-Pr can be observed more frequently in these patients compared to adults.

Adult↗

PubMed1993

Anti-Sa cold agglutinin of IgA class requiring plasma-exchange therapy as early manifestation of multiple myeloma.

The case of a patient (Col) with multiple myeloma presenting as chronic cold agglutinin (CA) syndrome is reported. The CA (Col) was a monoclonal IgA/k paraprotein which recognizes an antigen fully expressed in adult and newborn erythrocytes, sialidase sensitive and partially resistant to proteases. Hemagglutination-inhibition studies showed that immunodominant N-acetylneuraminic acid bound alpha 2-->3 to O-glycans of glycophorins represents the CA(Col) epitope. These serological and biochemical findings fit with the anti-Sa specificity, of which only two previous examples are known. The clinical manifestations of CA (Col) were characterized by marked acrocyanosis, generalized livedo reticularis, and incapacitating dyspnea, but only mild hemolysis. Plasma-exchange therapy was effective in quickly removing the CA and relieving the associated clinical manifestations, but such benefit was only temporary. This is the first reported example of anti-Sa CA of IgA isotype and the first case of IgA CA syndrome treated by plasma exchange.

Anemia, Hemolytic, Autoimmune↗

PubMed1993

IgA cold agglutinins recognize Pr and Sa antigens expressed on glycophorins.

Three cases of IgA kappa cold agglutinins (CAs) were studied. One had anti-Pr1 specificity, one had anti-Pra, and one had anti-Sa. The CAs recognize O-glycans of glycophorins. The findings supplement previous data on anti-Pr1 specificities of four IgA kappa CAs. Because all IgA kappa CAs described recognize O-glycans of glycophorins, a close association between the CA IgA isotype and specificities for O-glycans becomes apparent. It is unlikely, however, that the striking association reflects interrelations between IgA CA structure and specificity, because anti-Sa specificity and all anti-Pr subspecificities were originally defined with IgM CAs.

Adult↗

PubMed1993

Suppression of anti-erythrocyte autoantibody-producing B cells by a physiological IgG-anti-F(ab')2 antibody and escape from suppression by tumour transformation; a model relevant for the pathogenesis of autoimmune haemolytic anaemia.

We showed previously that broadly reactive IgG anti-immunoglobulin autoantibodies produced by rats during the immune response suppress the B cell response. We report here on the effect of a similar human antibody on self-reactive human B cells. IgG anti-F(ab')2 was added to cultures of anti-erythrocyte autoantibody-producing B cells derived from healthy donors. A dose-dependent suppression of the antibody response was obtained (maximum at 1.3 ng IgG/10(6) cells). This effect was competitively inhibited by F(ab')2 gamma. Autoimmune haemolytic anaemia can be caused by chronic monoclonal B cell proliferation. To reproduce this condition in vitro we immortalized B cells with Epstein-Barr virus (EBV) and raised a B cell population with anti-erythrocyte autoantibody activity. These cells were electrically fused with CB-F7 tumour cells and an IgG1 cold-reactive anti-erythrocyte autoantibody-producing B cell line was established. Surprisingly, the tumour cells were not suppressed by IgG anti-F(ab')2. It is known that anti-immunoglobulins selectively suppress antigen-receptor (AgR)-occupied B cells by a Fc gamma-receptor (Fc gamma R)-mediated mechanism. To occupy their AgR, we preincubated the tumour cells with anti-AgR antibody. In spite of this, their susceptibility to suppression was not restored. As shown by rabbit IgG-sensitized ox erythrocyte (EA)-rosetting, this refractoriness was not due to a loss of Fc gamma R. Our experiments delineate a mechanism of peripheral B cell suppression to autoantigens, and show a way of escape from control relevant for the pathogenesis of autoimmune haemolytic anaemia.

Anemia, Hemolytic, Autoimmune↗

PubMed1993

Cold autoagglutinins with anti-Pr specificity associated with fresh varicella infection.

Cold agglutinins with the rare anti-Pr specificity were identified in an adult patient with fresh varicella infection. The antibody was of the IgM kappa type with subspecificity anti-Pr3d and caused a haemolytic episode in the patient. In the only previously reported case in which cold agglutinins were associated with varicella infection, the antibody specificity was also anti-Pr.

Agglutinins↗

PubMed1992

Cold agglutinins of anti-Pr specificity in rubella embryopathy.

Cold agglutinins of anti-Pr specificity were detected in two newborn infants suffering from serologically ascertained rubella embryopathy, an IgM kappa anti-Pr(a), titer 64, and an IgM lambda anti-Pr1, titer 16. The cases are rare examples of cold agglutinin production in newborns; a possible relationship between anti-Pr specificity and rubella infection is discussed.

Agglutinins↗