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M Weigert

Publications and source records attributed to M Weigert.

At least 19 recordsLinked to original sources
PubMed1992

Selective pathogenicity of murine rheumatoid factors of the cryoprecipitable IgG3 subclass.

To analyze the involvement of rheumatoid factors (RF) in the generation of cryoglobulins and the development of related tissue injuries, we have established a panel of anti-IgG2a RF mAbs derived from MRL/MpJ-lpr/lpr (MRL-lpr), C3H/HeJ-lpr/lpr, and 129/Sv mice. After injection of hybridoma cells to normal mice, all four IgG3 RF mAbs induced cryoglobulinemia, and various degrees of glomerulonephritis and skin leukocytoclastic vasculitis. In contrast, none of the RF mAbs of the other isotypes generated cryoglobulins or tissue lesions. Since the same observation was obtained with another panel of five clonally related anti-IgG2a RF mAbs of MRL-lpr origin with almost identical heavy and light chain variable (V) regions but five different isotypes, it seems unlikely that the absence of pathogenicity of non-IgG3 RF mAbs was due to differences in fine specificity or V framework regions. In addition, the analysis of serum RF in MRL-lpr mice has demonstrated that a majority of 4 month old MRL-lpr mice produced substantial amounts of IgG3 RF with cryoglobulin activity. Because the cryoglobulin activity is associated with the murine IgG3 heavy chain constant region, RF of this subclass may play a significant role in the development of autoimmune-related tissue injuries, especially in MRL-lpr mice.

Animals↗
PubMed1991

Expression of anti-DNA immunoglobulin transgenes in non-autoimmune mice.

Self-reactive B cells can be regulated by either deletion or inactivation. These manifestations of self-tolerance have been dramatically shown in transgenic mice in which the number of self-reactive cells has been artificially expanded. We have now extended these models to ask if B-cell tolerance as described for non-disease-associated antigens also operates for the targets of autoimmunity. The target we have chosen is DNA. Anti-DNA antibodies are diagnostic of certain autoimmune syndromes in humans and are a characteristic of the murine model of systemic autoimmunity, the MRl/lpr mouse. Antibodies to both single-stranded and double-stranded DNA have been implicated in disease. By generating anti-DNA transgenic mice, we have addressed the question of whether DNA-specific B cells are regulated in normal (non-autoimmune) mice. We indeed found that most transgenic B cells bind DNA, yet we failed to detect secreted anti-DNA. We suggest that as a consequence of their self-reactivity these B cells are developmentally arrested.

Animals↗
PubMed1991

Ig H and L chain contributions to autoimmune specificities.

An Ig H chain expression vector has been constructed by using the V region of 3H9, an antibody that binds ssDNA, dsDNA, and cardiolipin. The H chain construct was transfected into six hybridoma cell lines expressing Ig L chains. All resulting H and L chain combinations had at least some affinity for ssDNA, whereas five also bound dsDNA to a similar degree as 3H9. The loss of dsDNA binding was correlated with a single amino acid difference between two V kappa 8 L chains. A further characteristic of 3H9, its immunofluorescent staining pattern, was shared by four of the recombinant antibodies, whereas its specificity for cardiolipin was shared with five. The transfections reported here show that a V kappa 3 L chain confers specificity for an RNA-associated epitope and that a V kappa 21E L chain prevents cardiolipin binding. These experiments suggest that the 3H9 H chain contributes essential determinants required for binding to DNA as well as cardiolipin but that L chains can modulate or prevent this binding. L chains may also expand the specificity of a recombinant antibody.

Amino Acid Sequence↗
PubMed1990

The BALB/c secondary response to the Sb site of influenza virus hemagglutinin. Nonrandom silent mutation and unequal numbers of VH and Vk mutations.

We have determined the nucleotide sequences of the expressed VH and Vk genes from 13 secondary (2 degrees) hemagglutinin (HA) (Sb) specific hybridomas derived from a single mouse. These antibodies share an Id, H37-68 (68Id) that dominates the 2 degrees HA(Sb) response in this mouse, but is rare or absent from 2 degrees responses of other mice. We find that these antibodies derive from five clones. The H chains of these antibodies are encoded by a single VH gene joined to a variety of DH and JH genes. The length of complementarity-determining region (CDR) 3 and sequence of the D-J junction are restricted, suggesting selection on CDR3 of the H chain. The L chains are more diverse. In the presented examples, they are encoded by the Vk21C and Vk21E genes and a Vk9 gene, and are joined to Jk1, 2, or 4. Each antibody is extensively mutated. The nature and distribution of the mutations suggests that 68Id-producing cells have been selected by Ag, although there are differences regarding the domain (VH, Vk, or both) in which mutations were selected. The implications of these findings on the idiosyncratic nature of the 68Id antibody response to HA(Sb) are discussed. There are two unusual characteristics regarding somatic mutation in these hybridomas. Whereas the expressed VH and Vk21 genes appear to have accumulated mutations at a high rate (1 to 1.5 x 10(-3)/base pairs/division, the expressed Vk9 genes appear to have accumulated mutations at a 5 to 15-fold lower rate than the expressed VH genes in the same cells. There is also a surprisingly high number of parallel silent somatic mutations in the VH genes, of which all but one are clustered to a 28-bp region in framework region 2 and CDR 2-encoding segments. The probability that this could have occurred by a random mutational process is essentially zero.

Amino Acid Sequence↗
PubMed1990

Heavy-chain class switch does not terminate somatic mutation.

We studied the H-chain class switch rearrangement in four groups of clonally related B cell hybridomas, to test the hypothesis that class switch terminates somatic mutation in a B cell. Using switch region-specific probes in Southern blot analysis individual mu-gamma switch rearrangement events can be distinguished. We show that clonally related IgG-producing hybridomas that differ by mutations often share a common switch rearrangement. This indicates that class switch in these cells did not terminate somatic mutation.

Animals↗
PubMed1990

Anti-DNA antibodies from autoimmune mice arise by clonal expansion and somatic mutation.

The proximate cause of autoantibodies characteristic of systemic autoimmune diseases has been controversial. One hypothesis is that autoantibodies are the result of polyclonal nonspecific B cell activation. Alternatively, autoantibodies could be the result of antigen-driven B cell activation, as observed in secondary immune responses. We have approached this question by studying monoclonal anti-DNA autoantibodies derived from unmanipulated spleen cells of the autoimmune MRL/lpr mouse strain. This analysis shows that anti-DNAs, like rheumatoid factors (19), are the result of specific antigen-driven stimulation. In addition, correlation of sequences with fine specificity shows that: (a) somatic mutations can cause specificity for dsDNA and that such mutations are selected for; (b) arginine residues play an important role in determining specificity; and (c) anti-idiotypes that recognize the majority of anti-DNA are probably not specific for any one family of V regions.

Amino Acid Sequence↗
PubMed1988

[Preventive stabilization of the knee joint by a bandage (brace) in an ice hockey player. Sense or nonsense?].

Braces for the knee are used by more and more First League Players to prevent injury to the knee, whether or not the knee has been injured previously. One player of the National Team wearing braces since last season complained of restricted efficiency. Electromyographical examination of his thigh muscles showed severe neurogenic changes. We concluded to refuse that so-called preventive braces.

Adult↗
PubMed1987

How immunoglobulin V kappa genes rearrange.

Recombination at the immunoglobulin kappa light chain locus creates a complete variable region gene and its reciprocal product. The results presented here show that reciprocal products may be substrates for secondary recombination and that at least one V kappa group rearranges by inversion.

Amino Acid Sequence↗
PubMed1987

Variable region sequences of murine IgM anti-IgG monoclonal autoantibodies (rheumatoid factors). II. Comparison of hybridomas derived by lipopolysaccharide stimulation and secondary protein immunization.

We have obtained the complete variable region mRNA sequences of 11 LPS-derived and 14 secondary immunization-derived monoclonal IgM anti-IgG antibodies (rheumatoid factors, RFs). A comparative analysis of these sequences showed that monoclonal RFs derived after polyclonal activation are structurally very similar to RFs derived after secondary protein immunization. This study was undertaken to evaluate the potential relationship between two previously described phenomena: (a) during a secondary response to a protein antigen, RF is produced in quantities that equal or exceed the immunogen-specific antibody; and (b) the frequency of B cells that make RF after polyclonal activation is quite high; 3-10%. It has been unclear whether LPS-stimulated cells that produce IgM anti-IgG that is detected by an in vitro assay are related to the cells that produce RF after in vivo stimulation. The similarity of the antigen receptors found in the two types of RF, however, suggests that most or all of the RF-producing B cells detected after LPS stimulation would also be stimulated during the secondary immune response. Thus, the presence of relatively large number of B cells that can make RF after nonspecific stimulation provides an explanation for the magnitude of RF production accompanying the secondary immune response.

Amino Acid Sequence↗
PubMed1987

A complex translocation at the murine kappa light-chain locus.

We have previously reported that a segment of DNA from a murine plasmacytoma comprises DNA from three chromosomes, the immunoglobulin kappa light-chain locus on chromosome 6, the S mu locus on chromosome 12, and a region on chromosome 15. We now report that the reciprocal product contains DNA from only the kappa locus and chromosome 15 and not from S mu. We conclude that a complex series of events, including both a transposition of DNA and a translocation between chromosomes, generated these imperfect reciprocal products.

Animals↗
PubMed1985

Inter- and intraclonal diversity in the antibody response to influenza hemagglutinin.

This study focuses on 10 BALB/c anti-influenza virus (A/PR/8/34) hemagglutinin antibodies that have light chains encoded by the same variable region kappa chain (V kappa) gene, V kappa 21C. A comparison of antibodies from lymphocytes of independent origin reveals the contribution of germline diversity (combinatorial joining and association) to this response. Although combinatorial joining and association contribute to sequence diversity, they appear to have little effect on the fine specificity of these antibodies. Somatic mutation, in addition to contributing to the sequence diversity of these antibodies, creates differences in their fine specificity. The extent of mutation and its effect on fine specificity can be seen by comparing antibodies of lymphocytes from the same clone. These intraclonal comparisons also indicate that somatic mutation is an ongoing process occurring at a high rate (estimated to be at least 10(-3) mutations per base pair per division) in the expressed V region heavy chain (VH) and V kappa genes. Furthermore, both the nature and distribution of these mutations suggest that amino acid replacement mutations in the light but not the heavy chain are selected for by antigen.

Animals↗
PubMed1985

Genetic polymorphism at the kappa chain locus in mice: comparisons of restriction enzyme hybridization fragments of variable and constant region genes.

Variable (V kappa) and constant (C kappa) region genes of the mouse kappa light chain have been compared in inbred strains and in geographically isolated or genetically separated populations of mice by Southern blot analysis of endonuclease-restricted germline DNA. In most cases, the C kappa gene is found on a single restriction fragment while the V kappa genes of the V kappa 19 and V kappa 21 groups are each found on several (6-18) fragments. The restriction fragment (RF) patterns of V kappa 19 and V kappa 21 groups are both polymorphic when compared among inbred mouse strains. Southern blot patterns of V kappa 21 and V kappa 19 of inbred strains are also found among some geographically isolated populations of mice, suggesting that inbred strains acquired kappa loci from different subspecies. Some populations of geographical isolates show V kappa 21, V kappa 19, and C kappa contexts similar to inbred mice while more distantly related species within the genus Mus and laboratory rats show no apparent similarity in context to inbred strains. Variable region genes determining the RF patterns of V kappa 19 and V kappa 21 appear to be linked to each other and to the C kappa and Lyt-3 loci.

Animals↗
PubMed1984

Generation of antibody diversity in the immune response of BALB/c mice to influenza virus hemagglutinin.

We have examined the amino-terminal sequence of the kappa light chains of a set of monoclonal antibodies specific for one of the major antigenic determinants (Sb) on the influenza virus PR8[A/PR/8/34(H1N1)] hemagglutinin molecule. This set was believed to be structurally related from earlier serological analysis that typed these kappa chains as members of the variable (V) region V kappa 21 group [ Staudt , L. M. & Gerhard , W. (1983) J. Exp. Med. 157, 678-704]. Our sequence analysis confirms and extends this conclusion; all examples of this set belong to a subgroup of the V kappa 21 group, V kappa 21C . A special feature of this set of kappa light chains is that all examples were derived from the same mouse (designated H36 ). This sequence analysis along with the characterization of gene rearrangements at the kappa light chain loci of these hybridomas is consistent with the idea that certain members of this set are the progeny of one or two lymphocytes. Because of this potential clonal relationship, we can reach several conclusions about the diversity observed among these kappa light chains: (i) the diversity is due to somatic mutation, (ii) somatic mutations occur sequentially and accumulate in the first complementarity-determining region, and (iii) the extent of somatic variation in this sample is high, suggesting a somatic mutation rate of about 10(-3) per base pair per generation.

Amino Acid Sequence↗
PubMed1983

Aberrant rearrangement of the kappa light-chain locus involving the heavy-chain locus and chromosome 15 in a mouse plasmacytoma.

The creation of a functional antibody gene requires the precise recombination of gene segments initially separated on the chromosome. Frequently errors occur in the process, resulting in the formation of a non-functional gene. The non-functional genes can be generated by incomplete rearrangements, frameshifts, or the use of pseudo V or J joining segments. It is likely that these aberrant rearrangements arise by the same mechanism as is used in generating functional genes, a process which we have suggested may involve unequal sister chromatid exchange. Aberrant rearrangements of immunoglobulin genes occur in normal lymphocytes and play a major part in allelic exclusion. However, it has recently been suggested that aberrant rearrangements involving immunoglobulin and non-immunoglobulin genes may be involved in tumorigenesis. This suggestion has been stimulated by the frequent occurrence of translocations involving chromosomes known to carry immunoglobulin genes in B-cell malignancies. The rearrangement of non-immunoglobulin DNA to the heavy-chain locus has recently been reported. Some aberrant rearrangements of the kappa locus appear to be due to rearrangements to sites that do not include the conventional sequence for V gene segment joining. Here we describe an aberrant kappa rearrangement that has led to the joining of DNA from chromosomes 15, 6 and 12, and so appears to be the result of chromosomal translocations or transpositions. As 15/6 or 15/12 translocations have frequently been found in mouse plasmacytomas (as have analogous translocations in human lymphocyte tumours) this aberrant kappa rearrangement may be unique to the plasmacytoma from which it was isolated.

Animals↗