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Biomedical subjects

H Waldmann

Publications and source records attributed to H Waldmann.

At least 235 records · Page 13Linked to original sources
PubMed1992

In vivo use of Campath-1G to prevent graft-versus-host disease and graft rejection after bone marrow transplantation.

Twenty-two patients (16 male, six female; median age 34 years, range 16-49) with acute myeloid leukemia (1st complete remission (CR), n = 9), acute lymphocytic leukemia (1st CR, n = 5), chronic myeloid leukemia (chronic phase n = 5, accelerated phase n = 1), malignant lymphoma (n = 1) and myeloma (n = 1) were transplanted with unmanipulated donor bone marrow after standard conditioning including the monoclonal antibody Campath-1G daily from day -4 to day 0. No further graft-versus-host disease (GVHD) prophylaxis was given. All patients engrafted and neither graft failure nor rejection were observed. Acute GVHD grade I (skin) was seen in 12 out of 21 patients at risk. Acute GVHD grade II (skin) occurred in two patients. Severe GVHD (grade III, IV) of the gut, liver and skin developed in two patients. The overall incidence of severe acute GVHD (II-IV) was 19% of the patients at risk. Chronic GVHD (skin only) was seen in eight patients (42%) (six of extensive severity). A total of 14 patients died, the causes being relapse (four), direct cytotoxic drug toxicity (one), a GVHD (two), disseminated varicella zoster (one), systemic tuberculosis (one), interstitial pneumonitis (three) and veno-occlusive disease (two). These results indicate that the intravenous administration of Campath-1G may have reduced the incidence of severe acute GVHD without the occurrence of graft failure. However, the incidence of chronic GVHD does not appear to have decreased.

Adolescent↗
PubMed1991

CD66 identifies a neutrophil-specific epitope within the hematopoietic system that is expressed by members of the carcinoembryonic antigen family of adhesion molecules.

Preliminary results from the IVth Leucocyte Culture Conference have classified the monoclonal antibody (MoAb), YTH 71.3.2, as CD66. Two other MoAbs, YPC 2/12.1 and CE6/2D3.1, share a common cellular specificity, reacting with cells of the neutrophil series and colonic epithelium. The YTH 71.3.2 and CE6/2D3.1 MoAbs both recognize a similar CD66 defined epitope that is distinct from that identified by YPC 2/12.1. By Western blotting, these antibodies react with different molecular species from cells of different lineages. The antibodies identify 50- to 55-Kd, 80- to 100-Kd, and 130- to 200-Kd components present in a semi-purified carcinoembryonic antigen (CEA) preparation from colonic adenocarcinomas and a 90- to 130-Kd molecule from HL-60 cells. With the colonic cell line, LS174T, YPC2/12.1 stains diffuse bands of 160 to 200 Kd and 90 to 130 Kd with equal intensity, whereas the binding of CE6/2D3.1 and YTH 71.3.2 is biased toward the lower molecular weight set of molecules. Remarkably, all three antibodies recognize CEA-related molecules. Defined analyses using HeLa cells transfected with CEA, NCA(NCA-50/90), and CGM6(NCA-95) cDNAs show that the three MoAbs identify CEA to varying degrees. While YTH 71.3.2 and CE6/2D3.1 also bind to NCA-50/90, YPC 2/12.1 recognizes an epitope expressed by both the NCA-50/90 and NCA-95 molecular species.

Antibodies, Monoclonal↗
PubMed1991

Reshaping a therapeutic CD4 antibody.

An immunosuppressive rat antibody (Campath-9) against human CD4 has been reshaped for use in the management of autoimmunity and the prevention of graft rejection. Two different forms of the reshaped antibody were produced that derive their heavy chain variable region framework sequences from the human myeloma proteins KOL or NEW. When compared to a chimeric form of the CD4 antibody, the avidity of the KOL-based reshaped antibody was only slightly reduced, whereas that of the NEW-based reshaped antibody was very poor. The successful reshaping to the KOL-based framework was by a procedure involving the grafting of human framework sequences onto the cloned rodent variable region by in vitro mutagenesis.

Amino Acid Sequence↗
PubMed1991

Transfection of human CD59 complementary DNA into rat cells confers resistance to human complement.

We have examined the role of the human CD59 antigen in inhibiting complement-mediated lysis by transfer and expression of a CD59 cDNA in rat cells. A cDNA encoding CD59 was subcloned into the expression vector pSFSVneo and stably transfected into the rat T cell line NB2-6TG. Indirect immunofluorescence staining using the anti-CD59 monoclonal antibody YTH53.1 demonstrated the presence of human CD59 antigen on transfected cells and its attachment to the cell surface by a rat glycolipid anchor. Transfected cells were found to contain a single 3.3-kb species of CD59 mRNA by Northern blot hybridization. Immunoblotting revealed that this encoded a protein band of the same size as that observed in human erythrocytes. To determine the biological effect of expression of human CD59 in rat cells, an assay was devised which measured the relative lysis of transfected cells compared to untransfected cells in the presence of human complement and a lytic monoclonal antibody. It was observed that CD59-transfected rat cells are less susceptible to lysis by human complement and that this effect was blocked by a F(ab')2 fragment of YTH53.1. These experiments provide a direct demonstration that CD59 can function as an homologous complement restriction factor for nucleated cells.

Animals↗
PubMed1991

Characterization of the CAMPATH-1 (CDw52) antigen: biochemical analysis and cDNA cloning reveal an unusually small peptide backbone.

The CAMPATH-1 (CDw52) antigen has been purified from human spleen. The antigenic epitope is heat stable but sensitive to mild alkali treatment. Experiments with phosphatidylinositol-specific phospholipase C indicate that it is anchored by a glycosylphosphatidylinositol (GPI) anchor. An N-terminal sequence of 11 amino acids was determined, followed by an abrupt stop. Using short overlapping mixed oligonucleotide primers, cDNA synthesized from the mRNA of a human B cell line was amplified by the polymerase chain reaction. The product was used to isolate cDNA clones and the full amino acid sequence of the CAMPATH-1 antigen was deduced. It consists of 37 amino acid residues plus a 24-residue signal peptide. It has all the features expected for a GPI-anchored membrane protein except that the predicted mature protein is remarkably short, comprising no more than 18 residues and possibly as few as 12 (depending on the GPI linkage site). Potential attachment sites for carbohydrate are present and it is shown that the antigen contains N-linked oligosaccharide(s). This structure accounts for the known properties of the antigen, though the exact reasons why it is such a good target for cell lysis in vitro and in vivo are not yet clear.

Amino Acid Sequence↗
PubMed1991

A humanized monovalent CD3 antibody which can activate homologous complement.

The rat monoclonal antibody (mAb) YTH12.5, specific for the CD3 antigen complex on human T cells has been modified in order to improve its efficacy in human therapy. With the aim of rendering it less immunogenic, it has been humanized using the method of framework grafting. During this process sequence analysis of the YTH12.5 VL gene indicated that it was of the lambda subclass, however, it was markedly dissimilar from previously published rat and mouse V lambda gene sequences and may represent a new V lambda gene family. The humanization of this light chain represents the first successful reshaping of a lambda light chain V region. To improve the effector function of the antibody we have created a monovalent form (1 Fab, 1 Fc) using a novel method involving the introduction of an N-terminally truncated human IgG1 heavy chain gene into cells producing the humanized CD3 mAb. Comparison of the mono- and bivalent humanized mAb in a complement-mediated cell lysis assay revealed that the monovalent antibody mediated lysis of human T cell blasts whereas the bivalent form did not. The availability of a humanized, complement-fixing CD3 mAb may improve opportunities for human therapy, in the management of organ rejection, autoimmunity and the treatment of T cell lymphoma.

Amino Acid Sequence↗
PubMed1991

Suppression in murine experimental autoimmune thyroiditis: in vivo inhibition of CD4+ T cell-mediated resistance by a nondepleting rat CD4 monoclonal antibody.

Genetically susceptible mice become resistant to experimental autoimmune thyroiditis (EAT) induction with mouse thyroglobulin (MTg) and lipopolysaccharide after pretreatment with deaggregated MTg (dMTg). Recent work showed this suppression to be mediated by CD4+ suppressor T cells (Ts). To study Ts action in vivo, we used a rat IgG2a monoclonal antibody (mAb), YTS 177.9, which modulates CD4 antigen in vivo without depleting CD4+ cells. Initial studies showed that after two 1-mg doses of mAb 7 days apart, extensive CD4 antigen modulation of peripheral blood leukocytes occurred within 4 days. Mice given CD4 mAb 24 hr before dMTg (2 doses, 7 days apart) were resistant to EAT induction when immunized with MTg and LPS 20 days later. Also, anti-rat IgG2a titers were reduced following challenge with heat-aggregated rat IgG2a compared to controls. Subsequent analysis of serum in CD4 mAb-treated animals revealed that mAb was present in the circulation for 14 days. Moreover, mice given CD4 mAb and dMTg, then challenged after only 10 days, when CD4 mAb was still circulating, developed a significantly higher incidence of thyroid damage than controls. These findings suggest that modulation of CD4 antigen does not interfere with Ts activation, but the presence of CD4 mAb, at the time of autoantigenic challenge, can interfere with tolerance to EAT induction. Thus, the direct relationship between the presence of CD4 mAb and inhibition of EAT suppression implicates a role for CD4 molecules in the mediation of suppression.

Animals↗
PubMed1991

Distribution of protectin (CD59), a complement membrane attack inhibitor, in normal human tissues.

Protectin (CD59) is a recently discovered 18-20 kDa glycoprotein that effectively inhibits lysis by the membrane attack complex of the homologous complement system. This glycoprotein is widely distributed on the membranes of human blood cells (erythrocytes and leukocytes). By using immunofluorescence microscopy, protectin was observed in vascular endothelia throughout the body and in extravascular tissues. Cells expressing protectin were also found in ductal epithelia of pancreatic, biliary, and salivary systems, bronchi, and kidney collecting ducts. Furthermore, protectin was expressed in the epidermis and in the syncytiotrophoblast of placenta. The expression of protectin in endothelia, in various epithelial cells, and in placenta presumably protects autologous tissues and the fetoplacental unit from complement-mediated damage.

Antigens, CD↗
PubMed1991

Humanized monoclonal antibody treatment in rheumatoid arthritis.

A 41-year-old woman with active, seropositive erosive rheumatoid arthritis was treated with the humanized monoclonal antibody Campath 1H. She had not responded or developed side effects to myocrisin, sulfasalazine and penicillamine, and had not responded to inpatient bedrest and physiotherapy. There was a rapid clinical improvement within 24 hours of infusion, which was maintained for about 12-14 weeks after the infusion. The lymphocyte count was suppressed for 7 months after treatment. There were no significant side effects during or after treatment. No anti-Campath 1H response was detected. This preliminary study suggests humanized monoclonal antibody therapy may be of value in the treatment of rheumatoid arthritis.

Activities of Daily Living↗
PubMed1991

New enzymatic protecting group techniques for the construction of peptides and glycopeptides.

The use of non-proteases for the selective removal of protecting groups from peptides and glycopeptides is described. The N-terminal deprotection of peptides can be achieved by the hydrolysis of the phenylacetyl (PhAc) amide blocking group catalyzed by penicillin G acylase. On the other hand, the lipase-mediated hydrolysis of n-heptyl (Hep) and 2-bromoethyl esters allows for the liberation of the C-terminal carboxy group. The selective C-terminal deprotection can be applied advantageously for the construction of acid- and base-sensitive polyfunctional O-glycopeptides. In all cases the enzymatic reactions are completely selective and proceed under mildest conditions (pH 7-8, r.t. to 37 degrees C) without damaging the various other functionalities present in the complex substrates.

Amino Acid Sequence↗
PubMed1990

Synthesis of 2-acetamido-2-deoxyglucosylasparagine glyco-tripeptides and -pentapeptides by selective C- and N-terminal elongation of the peptide chain.

The synthesis of protected 2-acetamido-2-deoxyglucosylasparagine glycopeptides, using the allyl ester as the C-terminal protecting group, their deprotection, and some possible applications of these glycopeptides for the synthesis of modified silica gels and the construction of liposomes are described. The selective carboxyl deblocking is achieved under neutral conditions by rhodium(I)-catalyzed isomerization of the allyl group followed by hydrolysis of the resulting propenyl ester. The tert-butoxycarbonyl group can be cleaved selectively in the presence of the allyl ester with hydrogen chloride in ether. The allyl ester and the acetates can be removed simultaneously with ammonia in methanol. This method opens up a preparative route to glycopeptide model structures of biological interest.

Amides↗
PubMed1990

Complement activation by immunoglobulin does not depend solely on C1q binding.

A matched set of rat chimeric antibodies has been studied for their ability to activate various key stages of the complement cascade. Rat IgM and IgG2b were efficient at all stages from C1q binding to cell lysis. However, for other isotypes, a direct correlation between C1q binding and cell lysis did not apply. IgG2a, which was only modestly efficient at C1q binding, was relatively more so for binding and activation of while C1, and was by far the most effective isotype after IgG2b and IgM for C4 and C3 binding. IgG2c was relatively efficient at binding C1q and C1, but less so for the binding of C4 or for later stages. IgA was efficient at binding C1, but again, this was not reflected in activation of later stages. The results suggest that properties of different isotypes, as well as influencing binding of C1q, may regulate attachment of the C1r2C1s2 tetramer. In addition, distinct features of certain isotypes may favor C4 activation and binding, independent of their ability to activate C1.

Antibody-Dependent Cell Cytotoxicity↗