PubMed Health⌕ Search

Biomedical subjects

D Holmberg

Publications and source records attributed to D Holmberg.

At least 55 records · Page 3Linked to original sources
PubMed1993

V-region directed selection in differentiating B lymphocytes.

We here analyse the repertoire of VH7183 rearrangements isolated from different stages of B cell differentiation in adult mice. The nucleotide sequence analyses of VH7183-D-JH rearrangements derived from large pre-B cells (B220+, mu-), small pre-B cells (B220+, mu-) and mature B cells (B220+, mu+) isolated from adult bone marrow revealed a sequential accumulation, among functional rearrangements, of D segments of the FL16 family and a depletion of D segments using the second and the third reading frame (RF). One member (VH7183.1) of the VH7183 gene family was utilized in 60-80% of the rearrangements of all populations analysed. In neonates the majority of the rearrangements utilizing this gene was found to be functional. In contrast, > 96% of the VH7183 rearrangements isolated from adult spleen were non-functional. These data provide evidence for cellular selection of VH regions acting at different points of the B cell differentiation pathway and at the transition of B cells from the bone marrow to the periphery.

Animals↗
PubMed1993

Analysis of VH gene utilisation in the non-obese diabetic mouse.

The immunoglobulin (Ig) heavy chain variable (VH) gene complexity and the VH gene utilisation pattern of the non-obese diabetic (NOD) mouse were investigated. We found that the NOD mouse displays a VH gene complexity which appears to be identical to that of the C57BL/6 mouse. Thus, Southern hybridisation using probes specific for 9 of the murine VH gene families revealed identical restriction fragment length polymorphism (RFLP) patterns in both mouse strains. As indicated by immunofluorescence analysis using allotype specific monoclonal antibodies the NOD mice were also found to carry the IgCH-1b allele. Collectively, these data suggest that the NOD mice carry an IgVH locus identical to that carried by C57BL/6. In contrast to the apparent identity at the level of germline VH gene repertoires, the pattern of VH gene utilisation differed considerably between these two mouse strains. Thus, in NOD mice the neonatal preference of D-proximal VH genes was found to be more pronounced than in C57BL/6 mice. Moreover, in contrast to adult C57BL/6 mice a D-proximal bias was evident also in adult NOD mice. On the basis of these findings we discuss the possibility that the distorted development of B cell repertoires in the NOD mouse could be directly or indirectly related to the T cell mediated, autoimmune process in the NOD mouse.

Alleles↗
PubMed1992

Developmentally controlled selection of antibody genes: characterization of individual VH7183 genes and evidence for stage-specific somatic diversification.

Nucleotide sequence analysis of a large number of rearranged immunoglobulin heavy chain V region genes allowed the identification of six new members of the VH7183 gene family. These six new genes plus the eight previously defined genes agrees with the previously estimated complexity of this gene family. Twelve of these genes were represented among the isolated clones. A comparison of the clones, derived from 1-day- and 14-week-old BALB/c mice, suggested a biased and developmentally controlled VH7183 gene utilization. Furthermore, a developmentally controlled, non-random distribution of the functional vs. non-functional VHDJH rearrangements was observed among clones utilizing genes of this family, suggesting unsuspected regulatory aspects of Ig rearrangements in the process of B cell differentiation. Finally, a limited junctional diversity was revealed among the neonatal clones as the result of a low frequency of N-sequence addition. A similar discrepancy was also observed between neonatal and adult VHJ558 clones. In conclusion, these data suggest a programmed generation of B cell diversity similar to what has been observed for the establishment of gamma/delta T cell repertoires.

Animals↗
PubMed1992

Selection against N-region diversity in immunoglobulin heavy chain variable regions during the development of pre-immune B cell repertoires.

The generation of Ig heavy chain chain diversity is dependent on the ordered rearrangement of three different, i.e. variable (VH), diversity (DH), and joining (JH), germline gene segments, exonuclease nibbling of the terminals of these gene segments, and the addition of template-independent nucleotide (N-sequences) in the junctions of these segments. The latter process has recently been reported to be limited within B cells formed during early ontogeny. In this study, we have analysed a large number of VHDJH rearrangements isolated from genomic DNA of adult and neonatal C57BI/6 mice using the polymerase chain reaction (PCR) technique. A comparison of functional versus non-functional VHDJH rearrangements derived from these PCR libraries, or from a set of previously published clones of BALB/c origin, revealed a selection against N-region diversity both in neonatal and adult B cell repertoires. This selection process is most pronounced in the early development of the immune system but can still be observed in the adult. Furthermore, selection against N-sequence additions was evident amongst neonatal VHDJH rearrangements utilizing both VH 7183 and VH J558 genes, but only in VH 7183 utilizing clones of adult origin. These results imply that in addition to a developmentally controlled onset of N-sequence additions, cellular selection against N-region diversity exist both in the neonatal and adult immune system.

Animals↗
PubMed1991

The phenotype of lymphoid cells and thymic epithelium correlates with development of autoimmune insulitis in NOD in equilibrium with C57BL/6 allophenic chimeras.

The mechanisms contributing to the development of autoimmune insulin-dependent diabetes mellitus have been analyzed in allophenic mouse chimeras of the NOD in equilibrium with C57BL/6 strain combination (where NOD is nonobese diabetic). Occurrence of lymphoid cell infiltration (insulitis) in pancreatic islets was observed in the majority of such chimeras. The development of insulitis was found to correlate with major histocompatibility complex chimerism in lymphoid cells and in thymus cortical regions. Chimeras with more than 50% of C57BL/6 lymphoid cells rarely developed insulitis. Our data suggest that the correlation with the thymic cortical region is absolute. Thus, all individuals displaying NOD or NOD/C57BL/6 thymic cortical regions developed insulitis, whereas we have not observed insulitis in chimeras with only C57BL/6 thymic cortical regions. Thus the positive selection of T cells appears to play a crucial role in the development of insulin-dependent diabetes mellitus.

Animals↗
PubMed1991

Population dynamics of natural antibodies in normal and autoimmune individuals.

We have measured the quantities of naturally occurring autoantibodies in the serum of normal, unmanipulated individuals. These changes over time following broad-band complex dynamical patterns that are similar in mouse and man. The patterns more likely reflect the network architecture of the natural antibody repertoire, regulating the activation and decay of individual clones. The temporal changes of both disease-specific and nonspecific autoantibodies are consistently modified in autoimmune individuals.

Animals↗
PubMed1991

Germ-line origin of functional idiotypic interactions: identification of two idiotypically connected, natural antibodies that are encoded by germ-line gene elements.

Two monoclonal, natural IgM antibodies derived from normal BALB/c mice were selected on the basis of being idiotypically complementary and functionally connected. Nucleotide sequence analysis of their respective heavy and light chain V regions showed that both of the clones expressed VH, D, JH, VL and JL gene segments of germ-line origin. Furthermore, none of the clones displayed N-sequence additions. These data suggest a germ-line origin of a functional idiotypic network and confirm a minimized contribution of somatic diversification through template-independent addition of N-nucleotides in neonatal B cell repertoires.

Animals↗
PubMed1991

Monoclonal, natural antibodies prevent development of diabetes in the non-obese diabetic (NOD) mouse.

The development of diabetes in the non-obese diabetic (NOD) mouse is mediated by T cells of both the CD4+CD8- and CD4-CD8+ phenotypes, while B cells are not involved in the effector stage of the disease. We have recently found, however, that treatments with heterologous, polyclonal immunoglobulin (Ig) preparations, as well as suppressing the developing B cell repertoire for the first 4 weeks of life dramatically reduce the incidence of disease and the severity of insulitis, in treated mice. We have further investigated the influence of Igs on the development of autoimmunity by testing the effect of polyclonal mouse-Ig or monoclonal, natural antibodies derived from normal, neonatal BALB/c mice. We found that repeated administration of high doses of polyclonal Ig (of xenogenic or isogenic origin), given at birth, inhibits the development of insulitis, as well as diabetes. Furthermore, single injections of moderate doses of isogenic, natural monoclonal antibodies (mAb) administered at the same age, while failing to significantly alter the degree of insulitis, efficiently prevent the development of disease. The effect of mAbs was found to be related to V-region specificity, as only some mAbs of a given isotype and origin had the observed effect.

Animals↗
PubMed1991

Immunoglobulin-mediated prevention of autoimmune diabetes in the non-obese diabetic (NOD) mouse.

We investigated whether the development of spontaneous T-cell-mediated type I diabetes in NOD mice is influenced by B cells and immunoglobulin (Ig). During the first 4 weeks of life, B-cell development was suppressed by repeated administration of rabbit anti-mouse IgM (RaIgM), while controls received polyclonal rabbit Ig (NRIg). A reduction in the incidence of diabetes, as well as in development of insulitis, was observed after either of these treatments. However, the effect on insulitis was more pronounced in mice treated with RaIgM compared with those treated with NRIg. Furthermore, while the optimal effect of NRIg was obtained after a single injection at birth, the additional effect of RaIgM on development of insulitis was observed only after continued treatment for the first 4 weeks of life. Taken together these data suggest a possible role of Ig/B cells in the development of autoimmunity in the NOD mouse. The additional effect observed after continued suppression of the neonatal B-cell development suggests that this population may contribute significantly to the establishment of an auto-aggressive lymphocyte repertoire in the NOD mouse.

Animals↗
PubMed1990

Genetic basis of the neonatal antibody repertoire: germline V-gene expression and limited N-region diversity.

We report here on the molecular characterization of heavy and light chain V-regions of antibodies isolated from the highly connected idiotypic network of the newborn BALB/c mouse. Nucleotide sequence analysis of eight hybridomas confirmed their germline origin. Furthermore, in contrast to most hybridomas and myelomas derived from adult mice, the majority of these clones were found to lack N-region sequences. These data show that somatic processes amplifying junctional diversity are relatively inactive early in ontogeny, and that germline gene expression alone ensures idiotypic complementarities in the developing immune system.

Animals↗
PubMed1989

Suppression of antibody responses to the acetylcholine receptor by natural antibodies.

Some relationships between "natural" physiological autoreactivity and antibody responses against the acetylcholine receptor (AChR) were investigated. Collections of unselected monoclonal antibodies were derived from nonmanipulated newborn mice of susceptible (BALB.B) and resistant (BALB/c) mouse strains, and screened for reactivity with heterologous AChR. Five in 200 BALB/c but none in 200 BALB.B clones were found reactive. Four of these anti-AChR antibodies were analyzed for connectivity to nine other antibodies in the same collection, and three of them found to react with a particular natural anti-idiotype. The functional in vivo significance of such natural idiotypic complementarities in the anti-AChR response could then be investigated. Treatment of BALB/c newborn animals with low (100 ng) or high (100 micrograms) doses of natural anti-idiotype significantly suppressed their anti-AChR antibody response when immunized as adults. The utilization of natural anti-idiotype reagents with broad reactivity patterns might overcome the known idiotype heterogeneity of the autoimmune antibody response to AChR and provide a strategy in prophylactic and therapeutic manipulation of disease development.

Animals↗
PubMed1989

Evidence for a functional idiotypic network among natural antibodies in normal mice.

We monitored in normal adult BALB/c mice the serum concentrations of four natural IgM antibodies, two of which show idiotypic complementarity in in vitro assays. In each individual, serum concentration of all four idiotypes were found to fluctuate in complex dynamical patterns with low correlation. The spectral power of some such patterns was found to be compatible with the existence of a chaotic regime. Groups of normal adult mice were injected intravenously with low (10 ng) or moderate (10 micrograms) doses of either of the two complementary idiotypes in saline. This treatment resulted in a pronounced inhibition of the fluctuation in the serum concentration of both complementary idiotypes for periods up to 3 months. Such compensations were not detected for the two unrelated natural idiotypes and were specifically induced, for they did not occur following the injection of unrelated antibodies. These results indicate the functional operation of an idiotypic network among natural antibodies.

Animals↗
PubMed1989

Establishment and functional implications of B-cell connectivity.

We have discussed some aspects of the structure of the normal immune system, particularly the B-cell compartment. We have argued: that a basic property of the natural antibody repertoire is constituted by high degrees of connectivity within the immune system as well as between the system and other components of the organism; that the complementarities constituting this connectivity are based on self-self interactions, high degrees of degeneracy or somatically selected interactions and that these properties are conserved through evolution, to ensure self-reference; that by evolutionary selection, antibody V-genes encoding such structural properties are ensured to be expressed early in ontogeny. The set of highly connected cells will be kept through ontogeny and form the basis for a compartment of naturally-activated lymphocytes making up 10-15% of the total lymphocyte population. As suggested before, this pool of connected cells may be responsible for maintenance of normal network dynamics and prevention of autoaggression.

Amino Acid Sequence↗
PubMed1987

The immune response to bacterial dextrans. V. A "dominant" idiotype in IgCHb mice.

A battery of syngeneic monoclonal anti-idiotypic antibodies was prepared against a monoclonal C57BL/6 anti-Dextran B512 antibody (17-9). Two such anti-idiotypes were shown to bind to sites on the 17-9 molecule which are related to the Dex-binding site and were used to characterize the anti-Dex antibody response in a number of inbred mouse strains. The results show that the 17-9 idiotype is recurrently expressed by all mice carrying the IgCHb haplotype, regardless of H-2 or background genes, and that this idiotype accounts for roughly one-half of the primary, specific response to Dex B512 in C57BL/6 mice. Backcross analysis confirmed the allotype-linkage of idiotype expression in the antibody response. Mice carrying other allotypes, however, had detectable levels of the 17-9 idiotype in normal sera, which was not associated with anti-Dex antibody activity and was not raised by specific immunization. Together with previous observations, these results characterize a second "recurrent" idiotype in the anti-alpha,1-6 response of IgCHb mice, both of which are expressed in the normal serum of all mouse strains tested.

Animals↗
PubMed1987

High connectivity, natural antibodies preferentially use 7183 and QUPC 52 VH families.

Twenty-seven B cell hybridomas derived from spleen cells of nonimmunized, 6-day-old BALB/c mice and previously characterized serologically were screened for VH-gene expression: hybridomas expressing the two most D-proximal VH-gene families, 7183 and QUPC 52 were over-represented in this sample. Strikingly, clones serologically characterized by high degree of degenerate "specificity" and high idiotypic connectivity were found to use almost exclusively these two VH-gene families. As these serological properties are a unique feature of "natural" antibody repertoires, the results may reflect a functional relationship between expression of these VH genes and activation of B cells in the internal environment, particularly in the context of idiotypic interactions.

Animals↗
PubMed1987

Idiotypic multireactivity of 'natural' antibodies. 'Natural' anti-idiotypes also inhibit helper cells with cross-reactive clonotypes.

One hundred and twenty IgM-secreting hybridomas derived from unmanipulated 6-day-old BALB/c mice were screened for reactivity with the prototype idiotypic and anti-idiotypic monoclonal antibodies, defining three well established systems, namely TEPC 15:10/13-15, J558:CD3.2, and MOPC 460:F 6(51). Up to 25% of all IgM antibodies reacted with at least one of the six specific ligands, half of the latter being 'monospecific', the others reacting with two or more antibodies. A detailed analysis of the four most multi-reactive clones showed individually specific patterns of reactivity and revealed reactions of the same IgM molecule in idiotypic systems previously studied independently. Furthermore, when tested for functional interactions with syngeneic helper T cells expressing MOPC 460-like clonotypes, one of these antibodies was found to inhibit effector helper activity. The results show the existence of 'natural antibodies' with idiotypic reactivities related to recurrent clonotypes in the strain. They may be either 'specific' or 'multireactive', and might connect idiotypes on T and B cells and on antigenic systems so far studied independently.

Animals↗