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A Radbruch

Publications and source records attributed to A Radbruch.

138 records · Page 8Linked to original sources
PubMed1982

Immunoglobulin V region variants in hybridoma cells. II. Recombination between V genes.

The mouse hybridoma line B1-8.delta 1 secretes a monoclonal IgD, lambda 1 anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibody with defined idiotypic determinants. Two spontaneous V-region variants (B1-8.V1/V2) with altered idiotope pattern were selected and the structural variation was located to the variable region of the heavy chain. The amino acid sequences of the B1-8. delta 1 and variant heavy chain V regions were determined. The variant VH regions are identical. Wild-type and variant VH regions differ in 10 positions. Single amino acid exchanges are found in the first and second framework at positions 20 and 43. The majority of replacements (eight substitutions) is clustered in the second complementary-determining region (CDR 2). There are no differences in CDR 1 and CRD 3 and the JH region. The variant, which at first glance appears to have undergone a series of point mutations, arose by recombination, possibly gene conversion, between the rearranged VDJ gene of the wild-type (B1-8.delta 1) and a neighbouring germ line VH gene encoding all of the substitutions.

Amino Acid Sequence↗
PubMed1982

Switch from NP-specific IgG3 to IgG1 in the mouse hybridoma cell line S24/63/63.

We have isolated by fluorescence-activated cell sorting an IgG1 expressing class switch variant (S24-1/47) from the IgG3-producing mouse hybridoma cell line S24/63/63. Both Ig bind the hapten 4-hydroxy-3-nitro-phenylacetyl (NP) with approximately the same affinity and fine specificity and are idiotypically indistinguishable. The apparent m.w. is 50,000 for the gamma 1 and 51,000 for the gamma 3 chain. The genomic DNA of IgG3-producing S24/63/63 cells contains a 14-kb Eco RI restriction fragment with C gamma 3 sequences representing a rearranged C gamma 3 gene. In the class switch variant S24-1/47 the C gamma 3 gene is deleted.

Animals↗
PubMed1980

Isolation of variants of mouse myeloma X63 that express changed immunoglobulin class.

We have used fluorescence-activated cell sorting with class-specific antisera to isolate spontaneous variants in the expression of immunoglobulin heavy chain class from the mouse myeloma cell line X63 (IgGI, kappa). In the wild-type cell population, only one type of variants was found, namely, cells expressing IgG2b. From an IgG2b variant clone we isolated secondary variants that had either reverted to IgGI expression or expressed IgG2a or IgG2a and IgG2b concomitantly. The variant heavy chains are of normal size. The variant immunoglobulins were characterized serologically, and all of them still expressed the wild-type idiotype. Wild-type and variant cell populations were screened for heavy chain class-switch variants by fluorescence microscopy. A variety of switch variants was found in addition to the ones isolated by cell sorting, and a clear pattern of class switching (gamma 1 leads to gamma 2b leads to gamma 2a leads to alpha) with frequent reversion emerges from this analysis. Cells expressing new heavy chain classes occurred at frequencies of about 10(-7)-10(-6)/cell per generation, whereas revertants were as frequent as 10(-6)-10(-5)/cell per generation.

Animals↗
PubMed1979

A new mouse myeloma cell line that has lost immunoglobulin expression but permits the construction of antibody-secreting hybrid cell lines.

We have isolated a subclone of the mouse myeloma cell line P3-X63-Ag8 that does not express immunoglobulin heavy or light chains. This clone X63-Ag8.653 can be used for efficient fusion with antibody-forming cells to obtain hybrid cell lines producing pure monoclonal antibodies. Screening of hybrid cell lines for specificity and immunoglobulin classes was done with a modified enzyme-linked immunosorbent assay.

Animals↗
PubMed1978

Isolation of myeloma variants with predefined variant surface immunoglobulin by cell sorting.

We describe a procedure for the isolation of somatic cell variants in which gene products are expressed on the cell surface that are not expressed in the wild type. Cloned cells of the myeloma line MPC 11, which expresses an IgG2b protein, were incubated with an antiserum specific for IgGI and IgG2a. Cells reacting with this antiserum were stained with a fluorescent anti-antiserum and enriched in three cycles of sorting in the fluorescence-activated cell sorter and subsequent growth in vitro. From the enriched population two variants were isolated by cloning in soft agar. One of them expressed a variant immunoglobulin that types serologically as an IgG2a but whose variable portion was idiotypically related to that of the MPC 11 wild-type protein.

B-Lymphocytes↗
PubMed1977

Robertsonian translocations in Mus musculus from Sicily.

The karyotypes of 6 mice from different places in Sicily have been determined. 3 of them had abnormal chromosome numbers of 2n = 26, 2n = 27 and 2n = 29, caused by Robersonian translocations of one acrocentric chromosome to another resulting in metacentric chromosomes. The newly described metacentric chromosomes are Rb(4.3)1Sic, Rb(15.2)2SIC, Rb(12.6)3SIC, Rb(13.5)4Sic, Rb(14.10)5Sic, Rb(17.8)6Sic and Rb(16.9)7Sic.

Animals↗
PubMedDate not supplied

Th1 and Th2 cells.

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Animals↗
PubMedDate not supplied

Drastic change in idiotypic but not antigen-binding specificity of an antibody by a single amino-acid substitution.

In proliferating B lymphocytes, somatic mutation of rearranged antibody variable (V)-region genes occurs at high frequency and may have a key role in the selection of these cells. It is of interest in this context to learn in which way single mutations can affect antigen binding and/or idiotypic specificity of an antibody. Previous investigations have analysed spontaneous mutants of myeloma and hybridoma cells in which the mutation affected the antigen-binding specificity of the antibody. Here we describe an antibody mutant that has fully retained antigen-binding specificity but has lost or drastically changed all V-region antigenic determinants (idiotopes) of the wild type as defined by monoclonal anti-idiotope antibodies. The mutant phenotype is generated by a glycine to arginine exchange in the middle of the diversity (D) element, at position 103 of the heavy chain.

Amino Acid Sequence↗
PubMedDate not supplied

Allergic sensitization and allergen exposure during pregnancy favor the development of atopy in the neonate.

BACKGROUND: Several studies have considered that the in utero environment plays an important role in the onset of the allergic phenotype. We assessed whether allergic sensitization and allergen exposure during pregnancy favor the postnatal onset of allergy in the neonate. METHODS: BALB/c mice were sensitized to ovalbumin (OVA) before mating followed by allergen aerosol exposure during pregnancy. T and B cell responses in offspring were followed up until day 60 postpartum. At the age of 4 weeks offspring were exposed to a heterologous antigen, beta-lactoglobulin (BLG). RESULTS: Pregnant mice developed immediate hypersensitivity responses and Th-2/ Th-0 immunity following allergen aerosol exposure. At birth, T cells from offspring of nonsensitized BALB/c mice were characterized by an impaired IFN-gamma production, which was lowered even further in offspring of OVA-sensitized BALB/c mice. Offspring of OVA-sensitized BALB/c mice responded with immediate-type cutaneous hypersensitivity reactions to OVA which could be related to the pre- and postnatal transfer of maternal OVA-specific IgG1 antibodies. After exposure to BLG, offspring of OVA-sensitized BALB/c mice developed an accelerated Th-2-driven immune response compared to offspring from nonsensitized BALB/c mice as indicated by enhanced anti-BLG IgG1 antibody production and increased numbers of positive immediate-type cutaneous hypersensitivity reactions to BLG. CONCLUSION: Our data suggest that Th-2/Th-0 immunity present during pregnancy has a decisive impact on shaping the Th-1/Th-2 T cell profile in response to postnatal allergen exposure.

Allergens↗