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C Berek

Publications and source records attributed to C Berek.

54 records · Page 3Linked to original sources
PubMed1985

Preliminary crystallographic study of the Fab fragments of two monoclonal anti-2-phenyloxazolone antibodies.

We report on the preparation, crystallization, and preliminary x-ray crystallographic study of the Fab fragments of two monoclonal anti-2-phenyloxazolone antibodies obtained from the secondary response to this hapten. The Fab fragment from one of these (NQ10/12.5) has been crystallized from polyethylene glycol 8000 solutions in a form suitable for high-resolution x-ray crystallographic studies. These crystals are monoclinic, space group C2, with a = 129.2 A, b = 79.4 A, c = 57.7 A, beta = 96.2 degrees, and one Fab/asymmetric unit. Determination of the three-dimensional structure of Fab NQ10/12.5 should help clarify the role of somatic mutation in the maturation of an immune response. This antibody and an anti-lysozyme antibody also under study apparently use the same germ-line encoded VK and a similar VH gene, respectively, as the idiotypic anti-oxazolone antibodies characteristic of the primary response. A comparative study of the two structures should shed light on the role of the pairing of heavy and light chains in the antigen-binding function of antibodies.

Animals↗
PubMed1984

The D segment defines the T15 idiotype: the immunoresponse of A/J mice to Pneumococcus pneumoniae.

In the immune response of BALB/c mice (Igha) to Pneumococcus the majority of antibodies express the idiotype of the myeloma protein TEPC 15 (T15). In contrast mice of the A/J strain (Ighe) do not express this idiotype. Using (BALB/c X A/J)F1, F2 or backcross mice it could be shown that in allotype heterozygous animals (Igha/e) Pneumococcus pneumoniae preferentially stimulates B cells expressing a heavy chain (H) encoded by genes in the BALB/c H chain gene complex. Phosphorylcholine (PC)-specific hybridoma lines were established from BALB/c and A/J spleen cells and idiotypically analyzed using monoclonal antibodies (mAb) specific for the T15 idiotopes 32/65, 10/13, 16/13 or 21A5. Whereas the majority of the BALB/c PC-binding mAb express these idiotopes, only some of the A/J mAb are positive for one or the other of the idiotopes formed by the variable (V) regions of the H and the light chain of the myeloma protein T15. However, 80% of the A/J PC-binding hybridoma proteins were bound by the anti-idiotopic mAb 21A5. This mAb is specific for a determinant partially formed by the C alpha and partially by the V regions of the myeloma protein T15. The mRNA of one of these T15- A/J PC-binding hybridoma lines was sequenced. VH and V kappa were identical with sequences found for BALB/c T15-like antibodies. The sequence of the D segment was structurally very different. The importance of the D segment in the dominant expression of the T15 idiotype is discussed.

Amino Acid Sequence↗
PubMed1983

An idiotypic determinant formed by both immunoglobulin constant and variable regions.

Immunoglobulin idiotypes are serologically defined determinants associated with the variable (V) region of antibody molecules (reviewed in refs 1-4). One of the best defined idiotype systems is that borne by the phosphorylcholine (PC)-binding IgA proteins TEPC15 (T15) and HOPC8 (H8). The T15 idiotype, defined by sera raised in A strain mice, or in rabbits, is considered identical to that expressed by the majority of BALB/c anti-PC antibodies. To define the idiotypic determinants (idiotopes) of which the T15 idiotype is comprised, monoclonal anti-T15 antibodies were used here to examine both serum and monoclonal anti-PC antibodies. The latter were found to differ from T15 with respect to the idiotope defined by the monoclonal anti-idiotope antibody, 21A5, in that the '21A5 idiotope' was absent from anti-PC sera; of the monoclonal anti-PC antibodies examined, only those which were both T15+ and of the IgA isotype seemed to express this idiotype fully. This result suggests that not only the V region, but also the constant (C) region, of the immunoglobulin molecule can contribute to the formation of an idiotypic determinant. Isotype-restricted idiotopes may be involved in the regulation of antibody responses of particular classes.

Animals↗
PubMed1983

Antibodies specific for different T15 idiotopes induce neonatal suppression of the T15 idiotype.

The response of BALB/c mice to Pneumococcus pneumoniae is dominated by a single idiotype defined by the phosphorylcholine-binding myeloma protein TEPC 15 (T15). Injection of newborn BALB/c mice with antibodies to the T15 idiotype will lead to suppression of this idiotype. Such mice will respond to the antigen Pneumococcus, but with idiotypically different anti-phosphorylcholine antibodies. In an attempt to further characterize the effect of anti-idiotypic antibodies on induction of tolerance, three monoclonal antibodies specific for different T15 idiotopes were used. Although these antibodies belonged to the mouse immunoglobulin classes, IgG1 or IgG2 alpha, and were derived from different mouse strains, in all cases, a long lasting suppression could be induced. The data show that injection of idiotope-specific antibodies will suppress the T15 idiotype, but not necessarily the idiotope itself. The results are discussed in terms of the mechanism which will lead to the suppression of a dominating idiotype in the newborn mouse.

Animals↗
PubMed1977

On the structure of the T-cell receptor for antigen.

Antigen-binding receptors of T lymphocytes were analyzed in two different ways. First, the idiotypic properties of T helper cells are studied using anti-idiotypic antisera prepared against isolated antibodies specific for A-CHO. These anti-idiotypic antisera are defined by immunogenetic and immunochemical means with respect to their reactivity with heavy- or light-chain-associated idiotypic determinants. Second, antigen-binding receptors are isolated from enriched T-and B-lymphocyte preparations and compared with respect to their reactivity with antigen and with class- or allotype-specific anti-Ig antisera. The results provide an incomplete picture of the T-cell receptor which shares with antibodies the variable region of the heavy chain but probably no other variable or constant portion.

Animals↗
PubMed1976

Genetics of the idotype of BALB/c myeloma S117: multiple chromosomal loci for Vh genes encoding specificity for group A streptococcal carbohydrate.

A small proportion of the antibodies to Group A streptococcal carbohydrate (A-CHO) elicited in BALB/c mice by immunization with Group A streptococci, has idiotypic determinants in common with the BALB/c myeloma protein S117 which has specificity for N-acetyl-glucosamine, the major antigenic determinant of A-CHO. The expression of these idiotypic determinants is under the control of a gene which is linked to the Ig-1a+ allotype locus in strain BALB/c and in other strains carrying the same Ig-1 haplotype. This gene (S117+) segregates in breeding experiments as if it were an allele to the gene A5A+ which controls the expression of the A5A idiotype in association with antibodies to A-CHO in strain A/J and which is linked to the Ig-1e allotype locus. Another possible allele, linked to the Ig-1c allotype locus, controls the expression of both S117 and A5A cross-reactive determinants (S117cr, A5Acr). The distribution of these idiotypic determinants in various lines that carry recombinant Ig-1 haplotypes suggests that the A5A and S117 loci are nonallelic and map at different positions in the Ig-1 region. The data suggest complex pseudollelic relationships between different Ig-1 haplotypes that allow the expression of the same genes in allelic and in nonallelic fashion.

Alleles↗
PubMed1976

Idiotypic analysis of lymphocytes in vitro. I. Specificity and heterogeneity of B and T lymphocytes reactive with anti-idiotypic antibody.

Guinea pig anti-idiotypic antibodies (anti-Id) of the IgG1 class, directed to an A/J antibody to Group A streptococcal carbohydrate (A-CHO), or directed to a BALB/c myeloma protein that binds the same antigen, stimulate B-precursor cells as well as T-helper cells when injected into mice of the appropriate strain. The strain-specific induction of both precursor and helper activity was detected by in vitro secondary responses of primed spleen cells to A-CHO or to 2,4,6-trinitrophenyl (TNP) upon challenge with Group A streptococcal vaccine (Strep.A) or with TNP-Strep.A, respectively. B- and T-cell populations primed with anti-Id were uniform with respect to the binding of antigen and of anti-Id. This was in contrast to cells primed with Strep.A, which were heterogenous. Taken together, B and T cells that possess the same antigen-binding specificity share idiotypic determinants, reveal the same idiotypic polymorphism, and may display similar degrees of heterogeneity with respect to the binding of antigen and anti-Id. Since the anti-Id used in this study detect Id determinants associated with the heavy chain of the variable region of mouse antibodies, the data suggest that this region of the immunoglobulin molecule is shared between T- and B-cell antigen receptors.

Acetylglucosamine↗
PubMed1976

Idiotypic analysis of lymphocytes in vitro. II. Genetic control of T-helper cell responsiveness to anti-idiotypic antibody.

When the IgG1 fraction of anti-idiotypic antibodies raised in guinea pigs is injected into mice, sensitization of idiotypic T and B lymphocytes occurs (1-3). In the present study we analyze the genetic requirements for T-helper cell sensitization by anti-idiotypic antibody. This was done by measuring, in a suitable panel of mouse strains, helper cell responsiveness to two anti-idiotypic reagents which recognize distinct, strain-specific idiotypes, namely the A5A and the S117 marker. Whenever helper cell sensitization by anti-idiotypic antibody was successful, helper function could be specifically inhibited by the same and only the same anti-idiotype. This indicates that helper cells induced by anti-idiotypic antibody express idiotypic determinants on their receptors for antigen. Helper cell sensitization by anti-idiotypic antibody was found in all strains expressing the corresponding or a cross-reactive idiotype at the immunoglobulin level. Idiotype-negative strains were always unresponsive to anti-idiotypic stimulation. In addition, responsiveness did not depend on the H-2 haplotype. Since the A5A and the S117 idiotype are markers for V genes in the heavy-chain linkage group, the present results support the view that the same genes in the Ig-1 complex code for variable portions of immunoglobulins and T-helper cell receptors.

Animals↗
PubMed1976

Structural studies on induced antibodies with defined idiotypic specificities. III. N-terminal amino acid sequence of the heavy and light chains of mouse anti-streptococcal antibodies--A5A, S8, and S117.

The murine VH genetic map consists of two different subloci of VH genes. Seven idiotypes have been allocated to these two different subloci, one of which contains genes coding for the A5A idiotype, while the second contains the genes encoding for six other idiotypic markers. Previous studies from this laboratory have shown that anti-Ars antibodies are best classified in the murine VHII subgroup. Studies from other laboratories indicate that the J558 idiotype could be classified in a similar fashion. The sequence of the T15 myeloma protein VH region is most characteristic of the murine VHIII subgroup. These studies were undertaken in order to study the VH subgroup of two additional murine VH markers. Since one of these markers has been allocated to a separate sublocus, comparisons can be made for the first time between the "framework" residues (VH subgroup) and the murine genetic map. The data indicate that within a single presently defined sublocus proteins exist which contain remarkably different "framework" residues.

Amino Acid Sequence↗
PubMedDate not supplied

An attempt to correlate an idiotype with antibody structure.

The expression of different idiotypic families encountered in the anti-phosphorylcholine antibodies depends on the association of a heavy chain with one of the VL sub-families. Manipulation of the response by idiotypic suppression leads to formation of a T15cr family whose structural correlates are analysed by determination of the mRNA sequence of hybridoma heavy and light chains.

Animals↗
PubMedDate not supplied

Somatic mutation and the maturation of immune response to 2-phenyl oxazolone.

Studies on the development of the immune response suggest that the repertoire of expressed antibody specificities is strongly influenced by antigen (reviewed in ref. 1). One way in which this influence is manifested is by a progressive increase in the affinity of antibody for antigen with time after immunization. This phenomenon, termed the 'maturation' of the immune response, must be due to a change in the structure of the antibody being synthesized. However, the precise nature of the changes involved and the genetic mechanisms used to produce them have not been clearly defined. We have now investigated the maturation of the immune response to the hapten 2-phenyloxazolone by mRNA sequencing of specific hybridomas. We conclude that somatic mutation of germ-line encoded genes plays a major role in the generation of antibodies with increased affinity for oxazolone with time after immunization.

Animals↗
PubMedDate not supplied

Molecular events during maturation of the immune response to oxazolone.

Sequence analysis of the heavy- and light-chain messenger RNA of hybridomas immunized with a specific hapten yields important clues about the interplay between genetic and selective events during the onset and maturation of the immune response. The maturation of the primary response to the hapten 2-phenyl-5-oxazolone is characterized by a drift to higher-affinity somatic variants of a germline-encoded basic sequence, whereas hybridomas from the secondary response demonstrate a further maturation dominated by a shift to alternative germline combinations.

Amino Acid Sequence↗