Biomedical subjects

L Wims

Publications and source records attributed to L Wims.

4 recordsLinked to original sources

PubMed2000

The role of carbohydrate in the assembly and function of polymeric IgG.

The carbohydrate present on glycoprotein can influence their biologic and functional properties. In the present paper we have assessed the role of oligosaccharides in the polymerization and effector functions of IgG with the 18 amino acid extension of IgM added to its carboxy terminus (IgGmutp). We found that IgG1mutp and IgG3mutp lacking the carbohydrate addition site in C(H)2, in the tail-piece or both assembled into polymers as well as the glycosylated versions. Aglycosylated polymers retained the ability to activate complement as assayed by C1q binding and hemolysis, although they were not as effective as their wild type polymer counterparts. Although IgGmutp lacking the carbohydrate in the tail-piece was able to bind to FcgammaRII, completely aglycosylated polymers lost the ability to bind to both FcgammaRI and FcgammaRII, suggesting a critical role for the C(H)2 sugar in FcR binding. Absence of the mutp carbohydrate increased the half life of polymeric IgG1, whereas absence of the carbohydrate in C(H)2 accelerated the clearance rate.

Carbohydrates↗

PubMed2000

Removal of amphipathic epitopes from genetically engineered antibodies: production of modified immunoglobulins with reduced immunogenicity.

Several approaches have been developed to reduce the human immune response to nonhuman antibodies. However, chimeric antibodies and humanized antibodies often have decreased binding affinity. We described a new approach for reducing the immunogenicity of chimeric antibodies while maintaining the affinity. This approach seeks to prevent the recognition of murine immunogenic peptides from the antibody variable region by human lymphocytes. Putative immunogenic epitopes in the variable region are identified and subjected to site directed mutagenesis to make them human and/or to break the amphipathic motifs. The R3 antibody, which blocks the epidermal growth factor (EGF) receptor, was used as a model system to test this approach. Four segments containing possible amphipathic epitopes were found in the heavy variable domain using the program AMPHI. Six amino acids within two of these segments were substituted by the corresponding residues from a homologous human sequence. No mutations were made in the murine light variable domain. Experiments in monkeys suggested that the "detope" R3 antibody was less immunogenic than its chimeric analogue. A search for possible amphipathic epitopes in the Kabat database revealed the presence of conserved patterns in the different families of variable region sequences, suggesting that the proposed method may be of general applicability.

Algorithms↗

PubMed1998

Deposition of genetically engineered human antibodies into the egg yolk of hens.

To determine if human immunoglobulins (hIg) are capable of being transported into the hen's egg, 10 microg each of purified hIgG and hIgA were intravenously injected into SC Hyline(TM) hens and their presence in egg yolk and egg white was determined by ELISA. In both cases deposition into the egg yolk was observed and in the case of hIgA, deposition was also observed in the egg white. Two stably transfected DT40 cell lines secreting recombinant human IgG3 and IgA (rhIgG3 and rhIgA) were injected into laying hens. The DT40 cells colonized the host and rhIgG3 and rhIgA were deposited in egg yolk. Deposition of rhIgA was also observed in the egg white. These data demonstrate that human immunoglobulins and other foreign proteins may be targeted to the chicken's egg. In view of the high rate of reproduction, the short generation interval, the high rates of egg production and the extensive infrastructure to fractionate egg yolk proteins, it should be possible to produce large amounts of foreign protein in the eggs of transgenic chickens.

Animals↗

PubMed1987

Genetically engineered antibody molecules and their application.

Immunoglobulin genes can be efficiently expressed following transfection into myeloma cells. Using protoplast fusion, transfection frequencies greater than 10(-3) can be achieved. Compatible plasmids containing two different selectible markers are used to simultaneously deliver heavy and light chain genes to the same cell. To produce molecules with differing specificities the rearranged and expressed variable regions can be cloned from the appropriate hybridoma. In some cases, variable regions from cDNAs can be inserted into the expression vectors. It is possible to manipulate the immunoglobulin genes and produce novel antibody molecules. Antibodies have been produced in which the variable regions from mouse antibodies have been joined to human constant regions. In addition, antibodies with altered constant regions have been produced. These genetically engineered antibodies provide a unique set of reagents to study structure-function relationships within the molecule. They also can potentially be used in the diagnosis and therapy of human disease.

Animals↗