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D Holmberg

Publications and source records attributed to D Holmberg.

At least 73 records · Page 4Linked to original sources
PubMed1986

Immunocompetent autoreactive B lymphocytes are activated cycling cells in normal mice.

Frequencies of B cell clonal precursors producing antibodies that react with mouse thyroglobulin, mouse erythrocytes, beef hemoglobin, KLH, and sheep erythrocytes were determined by limiting dilution analyses among small, resting lymphocytes, and among large activated cells from normal adult mice. While frequencies of clones reacting with external antigens were equally distributed in large and small B cells, most, if not all, autoreactive B lymphocytes were found in the large cell fraction. Analysis of antithyroglobulin hybridomas isolated from normal mice revealed dissociation constants ranging from 10(-6) to 5-6 X 10(-7). Treatment of normal donors with antimitotic drugs dramatically decreases the frequencies of autoreactive B cells, but not those of B lymphocytes reacting with external antigenic molecules. Taken together, these experiments show that immunocompetent, autoreactive B lymphocytes are activated and cycling cells in the peripheral lymphoid tissues of normal individuals.

Animals↗
PubMed1986

The high idiotypic connectivity of "natural" newborn antibodies is not found in adult mitogen-reactive B cell repertoires.

Unselected IgM-secreting hybridoma collections were established either from unprimed naturally activated newborn spleen cells or from mitogen-stimulated adult B cells. These were then screened for reactivity with a panel of monoclonal anti-idiotypic antibodies and haptens. While the finding of hapten-specific antibodies was equally frequent in either collection, newborn antibodies reacted at least 10 times more frequently with the anti-idiotypic reagents. The reactivity patterns of individual antibodies readily demonstrated the overall specificity of these V-region interactions. Since some of the idiotopes screened are characteristically not expressed in immune responses by the strains analyzed, and are in fact not expressed in the adult induced hybridoma collection, we explain these findings by a unique property of the set of natural (newborn) antibodies i.e. the high levels of idiotypic connectivity previously described within this repertoire.

Age Factors↗
PubMed1986

The immune response to bacterial dextrans. III. Ontogenic development and strain distribution of specific clonal precursors.

The frequencies of B512 dextran (Dex)-specific B cell precursors were determined by limiting dilution analysis in a number of mouse strains originally described as "high responder", "low responder" and "nonresponder" to this antigen. No significant difference in the frequencies of Dex-specific precursors was found in C57BL/6, B10.BR, C3H/Tif, BALB/c and A/Sn adult mice. Together with the large intra-strain variability in the magnitude of anti-Dex PFC responses in vivo, these results established that differential reactivity in vivo cannot be ascribed to genetically controlled absence or wide variation in the frequency of Dex-specific immunocompetent precursors. A similar analysis of the Dex-specific precursor frequency was carried out in C57BL/6 mice between 1 week and 3 months of age. While no Dex-specific antibody response was detected in vivo before the age of 3 weeks, clonal precursor analysis revealed that the appearance of these specificities parallels the development of competent (IgM-producing) B lymphocyte clonal precursors, such that no significant difference in absolute frequencies of Dex-specific precursors could be observed among these age groups. This is interpreted to suggest that the late development of the Dex-specific antibody responses is regulatory rather than due to late rearrangement and activation of the appropriate V genes and a sequential expression of antibody specificities in ontogenic development.

Age Factors↗
PubMed1985

Absence of immunoglobulin heavy chain expression results in altered kappa/lambda light chain ratios.

A few hundred hybridoma cell lines derived from spleen cells of normal, nonimmunized, 6-day-old BALB/c or BALB.B10 mice were screened for H- and L-chain production. Roughly half of these hybridomas produced no Ig chain into the culture supernatants. Of the Ig-secretors, 80% produced IgM molecules carrying either kappa or lambda chains in a ratio of 9:1. A surprisingly high frequency of clones (roughly 20%) were found to produce only light chains and in this group, the kappa/lambda ratio was altered to around 1. The indications from the primary screening were confirmed by isolating a large number of these hybrid cell lines and extensive testing of both culture supernatants and ascitic fluids in solid phase RIA and ELISA assays. In some cases, the absence or presence of heavy chain synthesis and the isotype of the light chain was also confirmed by biosynthetic labeling of the hybridoma clones, specific immuno-precipitation of cell lysates or supernatants, followed by analysis in SDS polyacrylamide gels. We conclude from these results that the absence of heavy chain expression is accompanied by frequencies of lambda chain expression, which are much higher than those observed in normal immunoglobulin producing cells, and equal to those of kappa chains. This conclusion can be interpreted as to suggest that the low frequency of lambda producing cells in mouse is in part determined by restrictions in the heavy-light chain interactions at the protein level.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1985

High frequency of natural autoantibodies in normal newborn mice.

Spleen cells from 6-day-old nonimmunized BALB/c and BALB.B10 mice were fused with the nonsecreting hybridoma cell line Sp2/0. Three hundred and eighty-four immunoglobulin-secreting hybrids were screened for antibody activity against mouse actin, tubulin, and myosin, and against TNP, peroxidase, renin, DNA, and neurofilaments. At least 24 hybridomas in the collection (6.25%) exhibited antibody activity against this panel of antigens. Ten of these hybrids were cloned, were propagated, and the corresponding monoclonal IgM protein was isolated from ascitic fluids and was further characterized. At least four groups of antibody specificities were identified: 1) one clone reacting with TNP only; 2) one clone reacting with both actin and tubulin; 3) two clones which bound to both TNP and actin; and 4) a fourth group, comprising the six other clones, which all exhibited widespread reactivity and bound to actin, tubulin, myosin, and TNP. These results indicate: 1) B cell clones directed against self antigens are activated in the internal environment and are recovered consequently by somatic cell hybridization; 2) the widespread antibody specificities found for these newborn mouse antibodies are very similar to those previously characterized with human natural antibodies and human monoclonal Ig; and 3) the frequency of B cells binding to cytoskeletal proteins and TNP is very high (at least 6.25%).

Animals↗
PubMed1984

Reactions among IgM antibodies derived from normal, neonatal mice.

Attempting to obtain a representative sample of the "natural antibody" repertoire in the developing immune system, we have derived IgM-secreting hybridomas from 4 normal untreated BALB/c mice of the same litter on day 6 after birth. Partially purified IgM preparations obtained in the supernatants of 70 such clones were each screened in binding assays for reactivity with a panel of 9 IgM antibodies, randomly selected from the same collection. Five of these 9 IgM antibodies were found to react with a considerable number of other IgM in the collection, while the other 4 showed only sporadic reactivity. On the other hand, more than half of the 70 antibodies were found to bind specifically to at least one of these five. With a few exceptions, these reactions showed quantitative levels ranging from 5 to 20% of those observed between either of the two interacting IgM and monoclonal rat anti-mu antibodies. The selectivity of these reactions indicated V-region specificity, which was confirmed by analyzing in some detail the reaction between 2 IgM antibodies isolated from the same mouse.

Animals↗
PubMed1984

Idiotypic determinants of natural IgM antibodies that resemble self Ia antigens.

A collection of immunoglobulin-secreting B-cell hybridomas was derived from normal neonatal BALB/c spleen and searched for reactivity against a panel of monoclonal anti-H-2 antibodies. We describe here one IgM antibody which was found to react with the monoclonal anti-Ia.7 antibody 14-4-4S. The characterization of this clone (BA.N 4:4.57) revealed its anti-trinitrophenyl specificity and demonstrated specific binding to five different monoclonal anti-Ia.7 antibodies but not to other anti-H-2 antibodies. The variable region specificity of these interactions was shown by the use of pepsin Fab fragments of the IgM antibody. Anti-Ia.7 antibodies were shown to specifically inhibit plaque formation by the hybridoma cells, and dinitrophenylglycine was shown to inhibit the reaction between the IgM antibody and anti-Ia.7 molecules. We interpret these results as to indicate that BA.N 4:4.57 expresses an idiotope or idiotopes which mimic Ia.7 determinants. This idiotypic family is naturally expressed in both newborn and adult BALB/c mice, as shown by the presence in normal serum of IgM molecules that specifically react with the F(ab')2 fragment of the 14-4-4S antibody. We speculate on the importance of idiotypic mimicry with major histocompatibility complex determinants, for both the selection of natural antibody repertoires and the evolution of antibody genes.

Animals↗
PubMed1984

The immune response to bacterial dextrans. IV. Antibody idiotypes.

Anti-idiotypic antisera (a-Id) were prepared in SJL mice against the dextran B512 (Dex)-specific hybridoma antibody D.16.6 (mu, kappa) of C57BL/6 origin. Such a-Id were specific for the D.16.6 antibody, but the idiotypic determinants recognized were not hapten modifiable. The a-Id were used in radioimmunoassays (RIA) to study the genetic control of the expression of the D.16.6 idiotype (Id) in a variety of mouse strains. It was found that all mouse strains tested expressed this Id as a component of the normal background immunoglobulin (Ig) in their sera. Only in mice of the IgCHb haplotype, however, was the Id found in association with Dex-specific antibodies. Furthermore, even in IgCHb mouse strains, not all individuals expressed Id-positive anti-Dex antibodies. Because the D.16.6 Id is a "recurrent" natural Id, but a "non-dominant" Id in the Dex response of IgCHb mouse strains, these observations contradict our previous suggestions on the selection of "dominant" Id from the pool of "naturally" produced Ig.

Animals↗
PubMed1983

Immune response to bacterial dextrans. II. T cell control of antibody isotypes.

The isotype distribution of Dextran B 512 (Dex)-specific plaque-forming cells (PFC) and serum antibodies was studied after in vivo immunization in C57BL/6 mice. Although IgG2b and IgG3 could also be detected in most individuals, the majority of non-IgM PFC were of the IgA isotype. All classes other than IgM were T cell-dependent, as shown by their complete absence in athymic "nude" mice. This unusual isotype pattern was further investigated by studying the antibody responses to the same Dex epitope coupled to a protein carrier, and to a different hapten coupled to the carrier Dex or to a protein. The results show that IgA responses are epitope-related and selectively associated with anti-Dex antibodies: no IgA PFC are detected against a hapten coupled to Dex or proteins, while the enhanced levels of helper cell reactivity provided by protein carrier to Dex result in the appearance of IgG1 antibodies in addition to IgA. These results indicate that T cells that modulate isotype patterns in these responses can discriminate between Dex- and DNP-specific B cells in the response to the same carrier. Since the same idiotype is detected on a large fraction of the IgM and IgA anti-Dex response and antiidiotypic helper cells have previously been detected in normal C57BL/6 mice, we suggest that idiotype-specific T cells control the production of IgA antibodies upon immunization with Dex.

Animals↗
PubMed1983

An example of major histocompatibility complex-linked control of idiotypic interactions.

Normal euthymic mice, injected i.v. with low doses of syngeneic monoclonal antibodies carrying "recurrent" idiotypes, develop a specific increase in numbers of splenic IgM plaque-forming cells that are paratopically and idiotypically similar to the injected antibody. We have now studied the responsiveness to a C57BL/6 anti-dextran a(1 leads to 6) and BALB/c anti-TNP (trinitrophenyl) monoclonal antibodies in a variety of strains. It was found that such responses are controlled by two linkage groups, namely major histocompatibility complex (MHC) and Ig-1.

Animals↗
PubMed1983

The immune response to bacterial dextrans. I. Genetic control of responsiveness.

The in vivo antibody response to the thymus-independent (TI) antigen dextran B512 (Dex) was studied in various mouse strains. We found no non-responder strains but rather that the magnitude of Dex-specific plaque-forming cell and serum antibody responses varied markedly among individual mice, even if these were of the same age and litter and kept in the same environment. This was the case both for mouse strains previously described genetically as high (IgCHb,j) and for those described as low (IgCHa) responders to Dex [14]. In 'low'-responder BALB/c mice, the responsiveness to Dex increased with age, such that a large fraction of these mice responded as well as 'high'-responder C57BL/6 mice. Analysis of aged back-cross populations derived from IgCHb and IgCHa parental strains further substantiated these findings. Thus, all backcross mice, irrespective of IgCH haplotype, responded on the average equally well to Dex. According to our studies, therefore, the assignation of high or low responsiveness to IgCH locus-linked genes cannot be done unequivocally.

Aging↗
PubMed1982

Antigen-independent, IgM-induced antibody responses: requirement for "recurrent" idiotypes.

Anti-idiotypic antibodies (a-Id) were produced in syngeneic mice against two monoclonal IgM antibodies of BALB/c origin, TNP. 11 and SP/603. In plaque inhibition tests, using IgM-secreting hybridoma cells and anti-idiotypic antibodies, these two IgM proteins, as well as the anti-TNP myeloma protein MOPC 460 (IgA) were found to carry non-cross-reactive idiotypes. Analysis of the anti-trinitrophenyl (TNP) plaque-forming cells (PFC) in BALB/c mice, either normal or immunized with TNP-horse red blood cells, revealed that in addition to the MOPC 460 Id, also the SP/603 Id is recurrent and expressed by a fraction of the anti-TNP antibody-secreting cells in all individuals tested. In contrast, the TNP. 11 Id could not be detected in any BALB/c mouse studied. TNP. 11 and SP/603 antibodies were then characterized by their ability to induce an antigen-independent anti-TNP response in normal BALB/c mice. While TNP. 11 was found to be inactive, the same titers of SP/603 IgM induced antigen-specific PFC all of which expressed the SP/603 Id, and increased titers of circulating IgM molecules carrying the same Id, suggesting that "recurrent" but not "nonrecurrent" Id are competent in this respect. A fraction of these SP/603-induced, SP/603-positive anti-TNP antibodies also carried MOPC 460 Id, suggesting expression on the same molecule of idiotypic determinants found on independent non-cross-reactive "recurrent" idiotypes.

Animals↗
PubMed1982

Idiotypic characterization of antibody-induced antibody responses.

Anti-idiotypic antisera were produced in syngeneic (C57BL/6) mice against a monoclonal anti-Dextran B512 (Dex) antibody (38-13). In radioimmunoassays, anti-idiotypic antibodies were shown to react with the homologous idiotype, while failing to recognize another monoclonal anti-Dex antibody, independently derived from C57BL/6 mice (D-16). Plaque inhibition tests confirmed the specificity of the anti-idiotypic antibodies and revealed that the 38-13 idiotype is expressed by about half of all anti-Dex antibodies produced in C57BL/6, but not in CBA mice. Injection of normal (but not athymic) C57BL/6 mice with low doses of 38-13 monoclonal antibodies, contained culture supernatants or ascitic fluids, resulted in a 10-20 fold increase in the numbers of anti-Dex PFC detected in the spleen 5 days later, the majority of which carried the 38-13 idiotype.

Animals↗