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B Arden

Publications and source records attributed to B Arden.

28 records · Page 2Linked to original sources
PubMed1984

Feedback regulation of immune suppression by a suppressor factor.

Mouse hybridomas generated by fusion between a lactate dehydrogenase-B (LDH-B)-specific B10.A(2R) T suppressor (Ts) cell line and the BW5147 thymoma secrete two suppressor factors, TsF-A and TsF-E. The factors carry the same antigen-binding chains but different major histocompatibility complex (MHC) chains (A beta-like and E beta-like, respectively). The TsF-A suppresses the proliferation of A-restricted, LDH-B-specific T helper (Th) cells. In this report we demonstrate that the addition of the TsF-E (isolated on immunosorbent columns with Ek- or Jk-specific antibodies) to the culture of LDH-B-primed B10.A(2R) lymph node cells turns the nonresponder (suppressed) cultures into proliferating ones, and that this change is antigen specific. This enhancing effect occurs in the early phase of the cell culture; the factor has no effect when added 2 days after the initiation of the culture. Because pretreatment of the Ly-2+ but not of the Ly-1+2- cells with TsF-E induces responsiveness, it is very likely that the targets of the factor are the Ts cells or their precursors that belong to the Ly-2+ subset. An incubation period of about 4 h is necessary for the TsF-E to exert its action. The enhancing effect of the TsF-E is abrogated by monoclonal antibodies specific for Ek and Jk antigenic determinants. However, only some of the antibodies that retain the TsF-E on the immunosorbent column neutralize the factor in a functional test. Antibody blocking studies also indicate that the MHC determinants involved in the interaction between the antigen-presenting and the Ts cell during Ts cell activation, and in the TsF-E Ts cell interaction are either very similar or identical. We interpret the data as indicating that the Ts cells or their precursors recognize the TsF-E with the same receptors as they use for the recognition of LDH-B together with the Ek on the antigen-presenting cells. The recognition of the TsF-E inactivates the Ts cell so that proliferation of Th cells then occurs unhindered. Thus, the production of the TsF-E may provide a feedback mechanism that regulates the activation of the Ts cells and, consequently, the degree of suppression in the response to LDH-B.

Animals↗
PubMed1984

Major histocompatibility complex of the mole-rat. I. Serological and biochemical analysis.

The mole-rat, Spalax ehrenbergi, is a complex subterranean rodent species whose habitat is restricted largely to the Middle East and North Africa. We typed over 50 mole-rats with mouse monoclonal and polyclonal antibodies specific for class I and class II major histocompatibility complex (Mhc) molecules. Some of these antibodies were produced against mouse Mhc molecules, others against Mhc molecules of other species. About 25% of the antibodies reacted with mole-rat lymphocytes in the cytotoxic test. Some of the serologically positive antibodies precipitated from a glycoprotein pool of mole-rat spleen cell molecules that corresponded in size with class I and class II molecules of other species. We conclude, therefore, that mole-rats, like other mammals, possess the Mhc which consists of class I and class II loci. We call this Mhc Spalax major histocompatibility (Smh) complex. The occurrence of a large number of different serotypes among the tested animals suggests that Smh loci are polymorphic. This Mhc polymorphism of the mole-rat contrasts with the monomorphism or oligomorphism of the Syrian hamster, a rodent with a similar ecology. Thus far no qualitative correlation could be found between Smh polymorphism and chromosome variation described in this superspecies.

Animals↗
PubMed1984

Composition of a suppressor factor that inhibits the immune response to lactate dehydrogenase B.

Hybridomas obtained by fusion of lactate dehydrogenase B (LDHB)-activated suppressor T (Ts) cells with the BW5147 thymoma produce a suppressor factor (TsF) that inhibits the proliferation of LDHB-activated helper T (Th) cells. A similar factor (TsE) is contained in the extract of suppressor hybridomas. Both TsF and TsE are specifically retained by LDHB-immunoadsorbent columns. Both consist of two components, an antigen-binding component (ABC) and possibly a major histocompatibility complex (MHC) component. The latter reacts with certain monoclonal antibodies specific for MHC determinants. The two components are covalently associated in the TsF and noncovalently associated in TsE. Mixing of the two components reconstitutes the activity of the TsF or TsE. Disruption of the ABC's tertiary structure results in its inability to reconstitute suppressive activity on mixing with the MHC components. The ABC may contain an intrachain disulphide bond(s). Suppression is obtained when Th cells are incubated first with the ABC and then with the MHC component or vice versa, provided that the incubation period is at least 4 h. The MHC component is also produced by nonsuppressor hybridomas but not by mitogen-stimulated blasts or by the parental thymoma. The TsF is a glycoprotein with a molecular weight of about 120,000 to 160,000. The molecular weight of the ABC is about 76,000-86,000 and of the MHC component about 30,000-37,000.

Animals↗
PubMed1983

Evidence for two suppressor factors secreted by a single cell suggests a solution to the J-locus paradox.

The hybridoma produced by the fusion of lactate dehydrogenase-B (LDH-B)-primed B10.A(2R) mouse suppressor T (Ts) cells with the BW5147 thymoma secretes two kinds of T suppressor factors (TsF), TsF-A and TsF-E. The TsF-A suppresses A beta-restricted and the TsF-E, E beta-restricted helper T (Th) cells. Each of the two factors consists of two polypeptide chains, an antigen-binding chain (ABC) and a major histocompatibility complex (MHC) chain. The ABC binds LDH-B, which is then recognized by one of the two receptors of the Th cell and an antigen bridge is formed between the factor and the Th cell. This chain is presumably identical in both factors. The MHC chain of the TsF-A carries antigenic determinants recognized by three sets of monoclonal antibodies: antibodies specific for the A beta chain, antibodies specific for class II determinants expressed in T cells and controlled by the A beta-E beta chromosomal segment, and antibodies crossreacting with J determinants. The MHC chain of the TsF-E carries determinants recognized by E beta-specific and by J-specific antibodies. Only some of these serologically detectable determinants reside in the region of the TsF molecule recognized by Th cells. These findings suggest that the J determinants are carried by the modified E beta and also by the modified A beta chains.

Animals↗
PubMed1982

Biochemical comparison of major histocompatibility complex molecules from different subspecies of Mus musculus: evidence for trans-specific evolution of alleles.

H-2 haplotypes were extracted from wild mice of three subspecies, Mus musculus domesticus, M. m. molossinus, and M. m. castaneus, that are known to have been separated from one another for some 1 to 2 million years. Serologically indistinguishable molecules controlled by some of the polymorphic H-2 loci were compared by tryptic peptide mapping, and the maps were found to be identical. In addition, a number of instances of biochemically indistinguishable H-2 molecules were found among wild mice and inbred strains of the M. m. domesticus subspecies. These findings suggest that some of the H-2 alleles have not altered for greater than 1 million years. To reconcile this apparent stability of H-2 genes with their extraordinary polymorphism (some 100 alleles at each of the polymorphic H-2 loci), it is proposed that the H-2 alleles evolve as if they were separate loci.

Alleles↗
PubMed1980

Structural comparisons of serologically indistinguishable H-2K-encoded antigens from inbred and wild mice.

H-2K glycoproteins from 2 wild-derived strains, B10.KPB128 and B10.GAA37, and from standard congenic lines B10.S(9R) and B10.A were compared by ion-exchange chromatography of tryptic peptides. The H-2K products of B10.S(9R) and B10.A were found to differ in about 33% of their peptides. The H-2K molecule of B10.S(9R) was indistinguishable from the H-2K molecules of B10.GAA37 and B10.KPB128. These results indicate that the H-2K-encoded products of the B10.S(9R), B10.KPB128, and B10.GAA37 lines are structurally very similar or, perhaps, identical, suggesting that some alleles of the H-2K locus may be maintained in a stable form in allopatric populations of wild mice.

Animals↗
PubMed1977

Major proteins of the Escherichia coli outer cell envelope membrane as bacteriophage receptors.

Three Escherichia coli phages, TuIa, TuIb, and TuII, were isolated from local sewage. We present evidence that they use the major outer membrane proteins Ia, Ib, and II, respectively, as receptors. In all cases the proteins, under the experimental conditions used, required lipopolysaccharide to exhibit their receptor activity. For proteins Ia and II, an approximately two- to eightfold molar excess of lipopolysaccharide (based on one diglucosamine unit) was necessary to reach maximal receptor activity. Lipopolysaccharide did not appear to possess phage-binding sites. It seemed that the lipopolysaccharide requirement reflected a protein-lipopolysaccharide interaction in vivo, and lipopolysaccharide may thus cause the specific localization of these proteins. Inactivation of phage TuII by a protein II-lipopolysaccharide complex was reversible as long as the complex was in solution. Precipitation of the complex with Mg2+ led to irreversible phage inactivation with an inactivation constant (37 degrees C)K = 7 X 10-2 ml/min per microgram. With phages TuIa and TuIb and their respective protein-lipopolysaccharide complexes, only irreversible inactivation was found at 37 degrees C. The activity of the three proteins as phage receptors shows that part of them must be located at the cells surface. In addition, the association of proteins Ia and Ib with the murein layer of the cell envelope makes this pair trans-membrane proteins.

Bacterial Proteins↗
PubMedDate not supplied

Diversity and structure of genes of the alpha family of mouse T-cell antigen receptor.

We have analysed 19 complementary DNA clones encoding the alpha-chain of the T-cell antigen receptor derived from thymic transcripts, and find that 15 of them contain partial or complete variable (V alpha) genes. Seven of these genes cross-hybridize to over 40 germline V alpha gene segments in Southern blot analyses. Of the 19 joining (J alpha) sequences examined, 18 seem to be encoded by distinct gene segments, hence the repertoire of J alpha gene segments is much larger than those of the immunoglobulin or T-cell receptor beta-chain gene families. We suggest that the variable domains of immunoglobulins and T-cell antigen receptors are similar in structure.

Animals↗