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Biomedical subjects

U Krawinkel

Publications and source records attributed to U Krawinkel.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of an HLA-DR4-restricted T cell clone recognizing a protein moiety of small nuclear ribonucleoproteins (UsnRNP).

In sera of patients with mixed connective tissue disease (MCTD, Sharp Syndrome) high titres of IgG autoantibodies to U1snRNP-specific proteins are found. The isolated occurrence of these autoantibodies is highly associated with the HLA-DR4 haplotype. snRNP-specific T cells are supposed to be involved in this autoantibody production. To address this question we cultured mononuclear cells from MCTD patients and healthy donors with a highly purified UsnRNP preparation from HeLa cells using bulk or limiting dilution cultures. Secondary responses to snRNP were detected only rarely with T cell lines from two patients and two controls, and turned out to be unstable during further expansion. One T cell line derived from a healthy individual retained its snRNP reactivity upon limiting dilution cloning and could be characterized in detail. The CD4+ T cell clone recognized native snRNP particles presented by monocytes in an HLA-DR4 (B1*0401)-restricted manner. Separation of the protein and RNA moieties of snRNP particles revealed that the T cell clone responded specifically to the protein fraction, but not to RNA and diverse control antigens. Sequencing of the T cell receptor alpha and beta chain cDNAs revealed that the clone used the V alpha 14.2 and V beta 14 elements. Upon antigen-specific and mitogenic stimulation the T cell clone showed a Th1-specific cytokine pattern, and did not provide helper activity for in vitro immunoglobulin production. This study demonstrate the presence of self-reactive snRNP-specific T cells in a healthy donor. The T cell clone may not represent a helper T cell for the formation of U1snRNP-specific autoantibodies.

Amino Acid Sequence↗
PubMed1993

Structural and functional properties of ribosomal protein L7 from humans and rodents.

By subtractive screening of a library made from mRNA of lipopolysaccharide (LPS)-stimulated mouse B lymphocytes we isolated cDNA-clones encoding the ribosomal protein L7. Human L7 mRNA was cloned from activated T-lymphocytes. Although no specific function of L7 in the translation apparatus is known as yet, it should be a critical one as indicated by its high degree of structural conservation during evolution and its regulated expression in lymphoid cells. Human and rodent L7 proteins carry sequences similar to the basic-region-leucine-zipper(BZIP)-motif of DNA-binding eucaryotic transcription factors. We show here that the region of L7 carrying the latter motif mediates L7-dimerization and stable binding to DNA and RNA. A preferential binding to RNA-structures is demonstrated.

Amino Acid Sequence↗
PubMed1993

Analysis of T cell receptor V beta regions expressed by rheumatoid synovial T lymphocytes.

The T cell receptor (TCR) V beta gene segment repertoire of T lymphocytes derived from peripheral blood of two healthy individuals and synovial tissue, synovial fluid and peripheral blood of three rheumatoid arthritis (RA) patients was analyzed. A sensitive assay based on the amplification of cDNA by the polymerase chain reaction (PCR) was used to analyze the levels of expression of 20 TCR V beta gene segment families. The relative expression of V beta gene segments in lymphocytes derived from peripheral blood, synovial tissue and synovial fluid was conserved over 155 days in one patient. V beta 9 transcripts were undetectable in the cells of this individual. In the two other patients the frequency of V beta 2 transcripts in synovial T cells of affected joints was significantly higher than in their peripheral blood lymphocytes. Dominance of distinct rearrangements among the V beta 2 transcripts from the synovial cells of these patients support the idea that the synovial T cell response is driven by antigen.

Amino Acid Sequence↗
PubMed1993

HLA-DRB1 gene sequences in HLA-DR4 positive and negative patients with rheumatoid arthritis.

The second exon of the DRB1 gene encoding for the first domain of the HLA-DR beta 1-chain was sequenced in 16 patients (10 DR4/DR1 positive, 6 DR4/DR1 negative) with seropositive rheumatoid arthritis (RA). We could confirm the strong association of susceptibility to RA with functionally equivalent conformations on otherwise distinct MHC molecules. At least one HLA-DR allele in all of the analysed DR4 or DR1 positive patients showed such an epitope with a minimal variability limited to residue 71. However, in HLA-DR4 and -DR1 negative patients such a similar epitope could not be detected.

Alleles↗
PubMed1992

Characterization of germ-line genes of the VGAM3.8 VH gene family from BALB/c mice.

Five germ-line genes of the VGAM3.8 VH family in BALB/c mice have been isolated from genomic libraries and sequenced. The genes are functional and three are expressed in antibodies of different specificities. Overall nucleotide sequence homologies within the family are greater than 90%, whereas homologies with other VH families are less than 70%. Southern blot hybridization and sequencing indicate a minimum family size of six genes. Differences in the coding regions are mostly confined to CDR, where there is a high replacement/silent substitution ratio, indicative of positive selection for diversification associated with Ag binding. VHVGAM3.8 sequences are highly conserved, and polymorphism in the coding regions appears to be very limited. Evidence is presented that the family has evolved, and been homogenized, by recombinatorial events.

Amino Acid Sequence↗
PubMed1992

Unusual sequence of immunoglobulin L-chain rearrangements in a gamma heavy chain disease patient.

Patients with gamma heavy chain disease (gamma-HCD) generally produce incomplete immunoglobulin (Ig) gamma-heavy chains (gamma-HCD protein) which cannot associate with light chains (IgL). In most patients Bence Jones proteins (BJP) are not observed. However, in the 61-year-old patient WIN we found gamma l-HCD proteins and lambda BJP in serum and urine. WIN gamma l-HCD protein does not carry the Ig Fd region, has a molecular weight of 33.5 kDa, and the seven N-terminal amino acid residues are not translated from any of the known immunoglobulin heavy chain (IgH) gene sequences. These residues are followed by the C gamma l-hinge region. In DNA from peripheral blood lymphocytes of patient WIN we found bands representing dominant rearrangements in one of the two alleles of the IgH, Ig kappa and Ig lambda locus. Taken together, the data from protein and DNA analysis strongly suggest, albeit do not formally prove, that one dominant B-cell clone which carries a rearranged and a non-rearranged allele of each Ig locus produces gamma-HCD protein and lambda BJP. The productive lambda-gene rearrangement in this clone thus has not been preceded by abortive rearrangements in both kappa-locus alleles. Lymphocytes with an unusual sequence of IgL-chain gene activation seem to be involved in the case of gamma-HCD described here.

Amino Acid Sequence↗
PubMed1991

Biased T cell receptor V alpha region repertoire in the synovial fluid of rheumatoid arthritis patients.

Synovial T lymphocytes seem to contribute to the pathogenesis of rheumatoid arthritis (RA). Since very little is known about the structural heterogeneity of their T cell antigen receptors (TcR), we analyzed TcR alpha chain mRNA of synovial fluid T cells from two RA patients. TcR alpha chain cDNA was amplified by the polymerase chain reaction with single-sided specificity for the alpha chain constant (C alpha) gene segment, and the nucleotide sequences of 51 functionally rearranged cDNA clones were determined. Twenty different V alpha genes and 26 different J alpha gene segments were utilized in these cDNA clones. Three of the V alpha gene segments which are frequently (8%-17% total) expressed in synovial fluid T cells have rarely been found in the TcR repertoire of peripheral blood T cells from healthy individuals. The T cell responses in the rheumatic synovia analyzed here are not oligoclonal, but the usage of TcR V alpha genes is biased.

Antibody Diversity↗
PubMed1991

[Gamma-1 heavy chain disease with the demonstration of Bence-Jones proteins].

We describe a 61-year-old patient suffering from gamma-1-heavy-chain disease (gamma 1-HCD) associated with Bence-Jones-lambda proteinemia and proteinuria. The analysis of the patients gamma 1-HCD protein (WIN) shows a deletion of the complete Fd fragment. The N-terminal seven amino-acid residue does not resemble any of the known immunoglobulin-heavy-chain variable regions. Unexpectedly, in PBL-DNA and in DNA from EBV-immortalized cells we found in addition to the expected predominantly rearranged Ig-lambda-light-chain gene a predominant rearrangement of an Ig-kappa gene. These findings show that the gamma-1-heavy-chain disease of the patient involves a defective regulation of Ig-light-chain-gene activation as well.

Amino Acid Sequence↗
PubMed1989

Physical linkage of variable, diversity and joining gene segments in the immunoglobulin heavy chain locus of the mouse.

The variable region of antibody heavy chains is encoded by multiple variable (V), diversity (D) and joining (J) gene segments which seem to be assembled in a programmed developmental pathway during the maturation of B lymphocytes. A physical map linking V, D and J gene segments in the a haplotype of the murine Igh locus is presented in this report. The V gene located next to the known D and J gene segments maps 80 kb upstream of the JH locus and is a member of the VGAM3.8 V gene family. There is evidence for as yet unknown D gene segments located 5' to this V gene.

Animals↗
PubMed1989

Recombination between VH pseudogenes.

The peculiar pattern of nucleotide differences between germline VH genes V104A/VAR104 and 122B could be the result of an exchange of genetic information through gene conversion. A palindromic sequence in one of the genes seems to have been the target site for the break that initiated recombination.

Animals↗
PubMed1989

Regulation of immunoglobulin gene rearrangement and expression.

The molecular genetic events leading to Ig expression and their control formed the topic of a recent EMBO workshop. This report by Michael Taussig, Martin Sims and Ulrich Krawinkel discusses contributions dealing with genes expressed in early pre-B cells, the mechanism of rearrangement, aberrant rearrangements seen in B cells of SCID mice, the feedback control of rearrangement as studied in transgenic mice, the control of Ig expression at the transcriptional and post-transcriptional levels, and class switching.

Animals↗
PubMed1989

Organization of the Ig VH locus in mice and humans.

In order to assess the contribution of the germline VH gene repertoire to antibody diversity, many groups have studied the evolution and the organization of the immunoglobulin VH gene locus in mice and humans. Here, Ulrich Krawinkel, Thomas Christoph and Thomas Blankenstein review recent data on this subject and discuss the potential influence of gene organization on the activation of the VH gene repertoire during the development of the mammalian immune system.

Animals↗
PubMed1988

A map of VH genes located next to the DH region in the Igh locus of two congenic Igh-recombinant mouse strains.

A new congenic mouse strain (C57BL/6-Igh-Vb-Ca) with a recombinant chromosome 12 is described. It carries the Igh-1a allele, but shows the serological characteristics of C57BL/6 when analyzed for idiotype expression with respect to the antigens dextran and (4-hydroxy-5-iodo-3-nitrophenyl)acetyl (NIP). We analyzed liver DNA from one animal for restriction fragment length polymorphism by hybridization to probes detecting members of nine VH gene families and DH segments, and compared it to DNA from animals carrying the nonrecombinant haplotypes Igha and Ighb, respectively. The breakpoint of recombination maps to the region carrying members of VH gene families VGAM3.8, PC7183 and Q52. The CB8KN strain which according to the serological analysis carries a recombinant Igh locus (Igh-Va-Cb) on BALB/c background was also analyzed. In this strain the breakpoint of recombination again maps to the region carrying members of VH gene families VGAM3.8, PC7183 and Q52. Our results show that the VH genes of families PC7183 and Q52 are interspersed and map to the region next to the DH locus. At least one gene from the VGAM3.8 family also maps to this region in the Igha and the Ighb haplotype.

Animals↗
PubMed1987

Immunoglobulin VH region genes of the mouse are organized in overlapping clusters.

Restriction fragment length polymorphism has been compared between the Igh loci of C57BL/6 and MOLF/EI (Mus musculus molossinus) mice utilizing probes which detect the C gamma 2b gene and genes from nine VH-gene families. Distinct restriction site patterns were found for the CH genes and for VH families PC7183, Q52 and X24. VH families V31 and J558 showed identical patterns. Mixed patterns of identical and distinct bands were detected in VH families S107, J606, V3660 and VGAM3.8. This indicates that a recombination took place involving the Igh loci of a M. m. molossinus and a progenitor of the C57BL/6 strain. The breakpoint of recombination maps to the chromosomal region carrying VH families S107, J606, VGAM3.8 and V3660. VH families PC7183, Q52 and X24 map 3' to the recombination breakpoint and proximal to the DH-JH-CH region, whereas VH families V31 and J558 accordingly map 5' to the recombination breakpoint and distal to DH-JH-CH. This order of VH families was confirmed by deletion mapping utilizing hybridomas which are haploid either for the Ighb or for the Igha locus. The mapping data indicate that the VH families of the mouse are organized in overlapping clusters. This notion is confirmed by demonstration of the physical linkage of VH genes from families V31 and J558 in the Igha locus.

Animals↗