SEARCH · PubMed Health

Results for “Complementarity Determining Regions”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

PubMed2001

Similar T-cell oligoclonality in antimitochondrial antibody-positive and -negative primary biliary cirrhosis.

Approximately 5% of patients with clinical and histological features suggestive of primary biliary cirrhosis do not have anti-mitochondrial antibodies that can be detected by current methodologies. Although the role of these autoantibodies in the pathogenesis of liver disease is uncertain, T lymphocytes within the portal tracts are felt to be important mediators of bile duct destruction. In order to investigate the hypothesis that a similar T-cell process may be involved in both antimitochondrial antibody-positive and -negative primary biliary cirrhosis, we characterized the oligoclonally expanded T cells in both types of patients by analysis of complementarity determining region 3 length in peripheral blood mononuclear cells. The distribution of oligoclonally expanded T cells was similar in both groups. This finding does not support a distinct T-cell-mediated pathogenesis for anti-mitochondrial antibody-positive and -negative primary biliary cirrhosis but rather suggests that similar processes may be involved in the immunopathogenesis of both.

Adult↗

PubMed2002

TCRs with high affinity for foreign pMHC show self-reactivity.

T cells with high-affinity T cell receptors (TCRs) for a foreign peptide-major histocompatibility complex (pMHC) appear to be negatively selected, even though they have never seen the foreign antigen. To examine how this process operates, we used in vitro yeast display to isolate high-affinity TCRs from the T cell clone 2C. The TCRs showed fast on-rates, which were consistent with reduced CDR (complementarity determining region) flexibility, and cross-reactivity with other cognate pMHCs. T cell hybridomas transfected with a high-affinity TCR were stimulated by endogenous self-pMHC, which suggested that T cells bearing the TCR would be negatively selected. The immune system appears to maintain a repertoire of flexible, low-affinity TCRs at the expense of more effective high-affinity TCRs.

Animals↗

PubMed2003

The crystal structure of human angiogenin in complex with an antitumor neutralizing antibody.

The murine monoclonal antibody 26-2F neutralizes the angiogenic and ribonucleolytic activities of human angiogenin (ANG) and is highly effective in preventing the establishment and metastatic dissemination of human tumors in athymic mice. Here we report a 2.0 A resolution crystal structure for the complex of ANG with the Fab fragment of 26-2F that reveals the detailed interactions between ANG and the complementarity-determining regions (CDRs) of the antibody. Surprisingly, Fab binding induces a dramatic conformational change in the cell binding region of ANG at the opposite end of the molecule from the combining site; crosslinking experiments indicate that this rearrangement also occurs in solution. The ANG-Fab complex structure should be invaluable for designing maximally humanized versions of 26-2F for potential clinical use.

Amino Acid Sequence↗

PubMed2003

Humanization of an anti-ICAM-1 antibody with over 50-fold affinity and functional improvement.

The monoclonal antibody 1A6 binds to human intercellular adhesion molecule 1 (ICAM-1, CD54) and inhibits infection by 90% of human rhinovirus (HRV) serotypes. To make a therapeutic molecule for preventing and treating HRV infection, we humanized a single chain antibody (scFv), 1A6, by a structure-guided complementarity-determining region (CDR) grafting procedure. Our final humanized 1A6 scFv does not retain any mouse back mutations in the framework. Without changing the CDR sequences, the humanized 1A6 scFv demonstrates over 50-fold improvement in both affinity for ICAM-1 and protection efficacy against HRV infection in vitro.

Amino Acid Sequence↗

PubMed2000

Germline repertoire of the immunoglobulin V(H)3 family in rhesus monkeys.

To facilitate molecular studies of antibody responses in rhesus monkeys (Macaca mulatta), we cloned and sequenced germline segments from its largest and most diverse immunoglobulin heavy-chain gene family, V(H)3. Using a PCR-based approach, we characterized 29 sequences, 20 with open reading frames (ORFs) and 9 pseudogenes. The leader sequences, introns, exons, and recombination signal sequences of M. mulatta V(H)3 gene segments are not strictly identical to those of humans, but the mature coding regions demonstrate, on average, greater than 90% sequence similarity. Although the framework regions are more highly conserved, the complementarity-determining regions (CDRs) also show strong similarities, and their predicted three-dimensional structures resemble those of their human homologues. In one instance, homologous macaque and human CDR1 sequences were 100% identical at the nucleotide level, and some CDR2s shared nucleotide identity as high as 96.5%. However, some rhesus V(H)3 ORFs have unusual structural features, including atypical CDR lengths and uncommon amino acids at structurally crucial positions. The similarity of rhesus and human V(H)3 homologues reinforces the notion that humoral immunity in this nonhuman primate species is an appropriate system for modeling human antibody responses.

Amino Acid Sequence↗

PubMed1992

Mechanism of allergic cross-reactions--III. cDNA cloning and variable-region sequence analysis of two IgE antibodies specific for trinitrophenyl.

As a first step toward defining the molecular interactions between ligands and the IgE antigen-combining site, we report here the cDNA cloning and variable (V) region nucleic acid sequences of the heavy (H) and light (L) chains of 2 monoclonal mouse IgE antibodies to trinitrophenyl (ATCC-TIB142 = IGELa2 and ATCC-TIB141 = IGELb4). In all instances, full-length cDNA clones were obtained to facilitate future expression studies. The H chains were encoded by VH genes from the VH3660 and J558 gene families in context with DQ52 and DSP2.2 diversity (D) mini genes, and JH3 and JH4 joining (J) gene segments, respectively. Vk8/Jk2 and Vk1/Jk5 rearrangements encoded the respective L chain V-regions. Both antibodies exhibited considerable conservation of complementarity determining region (CDR) sequences, which will facilitate template-based computer modeling of the three-dimensional structures of complexes formed between various ligands and these antibodies. From sequence comparison between the dinitrophenyl (DNP)-binding myeloma protein MOPC-315 and these IgE antibodies likely candidates for hapten-contact residues within the binding sites of IGELa2 and IGELb4 have been suggested.

Amino Acid Sequence↗

PubMed1992

Monoclonal antibodies to a CD4 peptide derivative which includes the region corresponding to an immunoglobulin CDR3: evidence of the involvement of pre-CDR3-related region in HIV-1 and host cell interaction.

A CD4 peptide of amino acid residues 68-130 [CD4(68-130)], which had the capacities to inhibit HIV-1 replication and HIV-1-induced syncytium formation, was used as an immunogen for the preparation of mAb. The mAbs prepared were classified into at least five types (I-V) in terms of their recognition sites by ELISA using various kinds of smaller CD4 peptides. Among them, the type I mAb no. 35 recognizing amino acid residues 72-84, which lies just before the region corresponding to an immunoglobulin third complementarity-determining region (CDR3), showed the strongest effects in reducing both HIV-1 infection and HIV-1-induced syncytium formation, although a large amount of no. 35 mAb was necessary to reduce such HIV-1 activities compared with those of anti-Leu-3a and OKT4A mAbs which recognize CD4 epitopes near a portion corresponding to an immunoglobulin CDR2. Western blot analysis showed that the reactivities of CD4 molecule in CD4-positive cells or sCD4 molecule with types I-V mAbs were stronger than that with anti-Leu-3a mAb. Flow cytometry showed that no. 35 mAb was faintly reactive with native CD4 molecule on cell surface at the concn showing the inhibitory effects on HIV-1 infection and syncytium formation. In addition, a smaller peptide CD4(66-92), one of the good epitope peptides for no. 35 mAb, also showed strong inhibitory effect on HIV-1 infection as well as a weaker inhibitory effect on syncytium formation. These results suggest that, in addition to the CD4 CDR2-related region, the pre-CDR3-related region is also involved in the early events of the interactions between the host cell and HIV-1.

Amino Acid Sequence↗

PubMed1999

Solution structure of a conformationally constrained Arg-Gly-Asp-like motif inserted into the alpha/beta scaffold of leiurotoxin I.

A monoclonal antibody, AC7, directed against the RGD-binding site of the GPIIIa subunit of the platelet fibrinogen receptor, interacts with activated platelet. The H3 region (H3, RQMIRGYFDV sequence) of the complementarity-determining region 3 heavy chain of AC7 inhibits platelet aggregation and fibrinogen binding to platelet. H3 contains the arginine, glycine and aspartate residues, but in an unusual order. The solution structure of the decapeptide has been studied by proton NMR. The NMR data suggested a helical equilibrium. To test whether the helical structure of H3 was biologically relevant, a conformationally constrained peptide with the RGD-like motif was designed. The sequence of a scorpion toxin (leiurotoxin I) has been modified in order to constrain the H3 sequence in a rigid helical conformation. The structure of leiurotoxin I consists of a beta-sheet and an alpha-helix, linked by three disulfide bridges. The structural feature of the chimeric peptide (H3-leiurotoxin) has been determined by standard two-dimensional NMR techniques. H3-Leiurotoxin structure closely resembles that of leiurotoxin I.

Amino Acid Sequence↗

PubMed1979

Some sequence similarities among cloned mouse DNA segments that code for lambda and kappa light chains of immunoglobulins.

A comparison between the cloned mouse DNA segments that were found to code for the lambda and kappa light chains of immunoglobulins established that there were seven short nucleotide sequences, two of which matched 6 out of 7, two 7 out of 8, two 8 out of 9, and one 9 out of 10 bases; these sequences were located either at homologous amino acid positions or at positions displaced by four amino acids or less. They all occurred in the framework regions (FRs), five next to the complementarity-determining regions (CDRs). Three of these were unique and did not occur elsewhere in the immunoglobulin nucleotides sequenced thus far or in DNA's of phage phi X174, phage G4, or simian virus 40. Five could serve as sites of joining by recombination or insertion of CDR to FR segments, and the invariant tryptophan that is the first residue of the second FR might serve as a sixth. These sites are consistent with the mini-gene or insertional hypotheses for the generation of antibody diversity but could also serve as points of recognition for a mutator enzyme or could serve to limit somatic mutation to the CDRs.

Amino Acid Sequence↗

PubMed1994

Analysis of patterns of DNA sequence variation in flanking and coding regions of murine germ-line immunoglobulin heavy-chain variable genes: evolutionary implications.

We analyzed the DNA sequence structure of the 5' flanking and coding regions of 52 VH186.2-related germ-line genes isolated by PCR from C57BL/6J and BALB/c mice. The aligned coding regions display hypervariable and conserved regions corresponding to some of the complementarity-determining regions (CDRs) and framework regions (FRs) found in somatically mutated rearranged immunoglobulin variable genes. Most of the coding regions (88.5%) display open reading frames, strongly suggesting positive selection by antigen. Phylogenetic comparisons of putative transcribed regions versus 5' nontranscribed regions show that they have evolved very differently. Inspection of the 52 murine VH186.2-related DNA sequences (as well as other vertebrate germ-line V sequences reported in the literature) reveals clusters of insertion and deletion events bracketing the transcription/coding unit. These data strongly suggest hyperrecombination events targeting the putative transcription/coding sequence. Given that the DNA of unrearranged germ-line V elements cannot be the direct target for "natural-selection" antigen-binding forces (since V elements are only expressed somatically when rearranged in a mature lymphocyte), it is difficult to explain how these nonrandom sequence variations appear in the germ-line DNA. A number of molecular genetic processes are considered, including antigen-driven soma-to-germ-line gene feedback operative during vertebrate germ-line V gene evolution.

Amino Acid Sequence↗

PubMed2006

Pathogenesis of B-cell superantigen-induced immune complex-mediated inflammation.

Staphylococcal protein A (SpA) is representative of a new class of antigens, the B-cell superantigens (SAgs). These antigens bind to the Fab regions of immunoglobulin molecules outside their complementarity-determining regions. SpA, the best-studied B-cell SAg, reacts with the Fabs of most VH3+ immunoglobulins, which are expressed on 30 to 60% of human peripheral B cells. Therefore, B-cell SAgs like SpA have great potential to elicit inflammatory responses in vivo. We previously reported that the interaction of SpA with VH3+ immunoglobulin molecules leads to activation of the complement cascade and produces a histologic pattern of inflammation in the skin of a rabbit indicative of immune complex injury. To elucidate the cellular and molecular events contributing to this type of unconventional immune complex-mediated inflammation, we established a mouse peritoneal Arthus reaction model. Mice treated intravenously with human polyclonal immunoglobulin G (IgG), followed by intraperitoneal injection of SpA, showed neutrophil influx into the peritoneal cavity with peak numbers appearing at 8 h. This inflammatory reaction was dependent on the interaction of SpA with VH3+ IgG. Mast cells, FcgammaRIII, complement components, and tumor necrosis factor alpha play obligatory roles, and the reaction is associated with the local release of the CXC chemokines macrophage inflammatory protein 2 and KC. The data provide further compelling evidence for the induction of immune complex-mediated injury by a B-cell SAg and highlight important factors contributing to the pathogenesis of this novel type of inflammatory reaction.

Animals↗

PubMed1988

Comparison of latent and nominal rabbit Ig VHa1 allotype cDNA sequences.

The genetic basis for the expression of a latent VH allotype in the rabbit was investigated. VH region cDNA libraries were produced from spleen mRNA derived from a homozygous a2a2 rabbit expressing an induced latent VHa1 allotype and, for comparison, from a normal homozygus a1a1 rabbit expressing nominal VHa1 allotype. The deduced amino acid sequences of the nominal VHa1 cDNA were concordant with previously published VHa1 protein sequences. A comparison of two complete VH-DH-JH and six partial VHa1 sequences reveals highly conserved sequence within VH framework regions (FR) and considerable diversity in complementarity-determining regions and D region sequences. Two functional JH genes or alleles are evident. Amino acid sequencing of the N-terminal 15 residues of pooled affinity-purified latent VHa1 H chain showed complete sequence identity with the nominal VHa1 sequences. Possible latent VHa1-encoding cDNA clones, derived from the a2a2 rabbit, were selected by hybridization with oligonucleotide probes corresponding to the VHa1 allotype-associated segments of the first and third framework regions (FR1 and FR3). cDNA sequence analysis reveals that the 5' untranslated regions of nominal and latent VHa1 cDNA were virtually identical to each other and to previously reported sequences associated with VHa2 and VHa-negative genes. Moreover, some latent VHa1 genes encode FR1 segments that are essentially homologous to the corresponding segment of a nominal VHa1 allotype. In contrast, other putative latent genes display blocks of VHa1 sequence in either FR1 or FR3 that are flanked by blocks of sequence identical to other rabbit VH genes (i.e., VHa2 or VHa-negative). These composite sequences may be directly encoded by composite germ-line VH genes or may be the products of somatically generated recombination or gene conversion between genes encoding latent and nominal allotypes. The data do not support the hypothesis that latent genes are the result of extensive modification by somatic point mutation.

Amino Acid Sequence↗

PubMed1993

Primary sequence and location of the idiotopes of V-88, a DNA-binding monoclonal autoantibody, determined by idiotope scanning with synthetic peptides on pins.

In this study, the primary sequence and location of the idiotopes of monoclonal antibody (mAb) V-88 have been examined. V-88 was derived from an adult (NZB x NZW)F1 mouse, has been partially defined previously with polyclonal anti-idiotype antisera, and is a member of the 16/6 idiotype (Id) family. From the inferred primary amino acid sequence of the antibody, sets of hexapeptides, overlapping by five residues, were synthesized on pins and used to scan the expression of epitopes (idiotopes) in the V regions of the light and heavy chains. A heterologous rabbit antiserum raised against the native antibody V-88, and absorbed to make it idiotype specific, was found to react with eight major epitopes distributed between the VH and VL regions. Half of these determinants mapped to the complementarity determining regions, with the others in framework sequences. Thus, the idiotype of antibody V-88 comprises, at least in part, continuous linear idiotopes in both hypervariable and framework areas. The process of absorbing the anti-idiotype antiserum on normal mouse immunoglobulin removed much of the background antibody activity against V region peptides, but left the activity against the dominant idiotopes. The sequence of a major idiotope, VATISG, in the FW2/CDR2 VH region is homologous to sequences of human antibodies that express the 16/6 idiotype, suggesting that Id.16/6 is at least in part defined by this region of the antibody. The same VH area is also homologous to sequences in bacterial and mammalian heat-shock proteins (hsp60-65). Thus there may be a functional link through idiotype connections, especially those involving Id.16/6, between anti-bacterial responses and production of autoantibodies, and some bacterial antigens may function indirectly as superantigens for B cells.

Amino Acid Sequence↗

PubMed1995

[Construction and clinical application of chimeric antibodies].

To reduce the high immunogenicity of mouse monoclonal antibodies (MAbs) in man, mouse/human chimeric antibodies have been generated in two ways. The more simple method is to construct chimeric antibodies in which the variable regions from the mouse MAbs are linked to human constant regions. The second is to graft the complementarity determining regions from the variable regions of mouse MAbs into human variable regions. So far, more than a hundred of chimeric antibodies have been reported and about twenty-five have been tried for immunotherapy of various human diseases. In the near future, many mouse/human chimeric antibodies will be commercially available.

Animals↗

PubMed1996

Light chain cardiomyopathy. Structural analysis of the light chain tissue deposits.

Cardiomyopathy due to monoclonal light chain deposits is a complication of plasma cell disorders. The deposits may be either fibrillar as in light chain amyloid or nonfibrillar as in light chain deposition disease. The reasons for these structural differences are still unknown. We characterized the myocardial deposits by immunohistochemical examination of sections and extraction and biochemical analysis of the tissue deposits in a patient (MCM) who died of myeloma and systemic light chain deposition disease. Amino acid sequence analysis of the extracted nonfibrillar MCM kappa-light chain reveals that it belongs to the L12a germline subset of the kappa(I) protein and contains five distinctive amino acid substitutions (three in the framework region III and two in the complementarity-determining region III) that have not been reported previously in the same positions in other kappa(I) light chains. The theoretically determined isoelectric point (pI 8.21) of the MCM light chain is high compared with the low isoelectric point of other Bence Jones proteins from subjects without light chain deposition disease. The diffuse binding to basement membranes and the high isoelectric point of the MCM kappa-light chain suggest electrostatic interaction as a possible mechanism of tissue deposition. The spatial locations of the five distinctive residues and a sixth rare substitution of the MCM protein modeled on the backbone structure of REI, a kappa(I)-soluble Bence Jones light chain of known three-dimensional structure, may be responsible for protein destabilization, partial unfolding, and aggregation leading to tissue deposition.

Adult↗

PubMed1998

In vivo inflammatory response to a prototypic B cell superantigen: elicitation of an Arthus reaction by staphylococcal protein A.

Staphylococcal protein A (SpA) is representative of a new class of Ags, the B cell superantigens (SAgs). These SAgs, unlike conventional Ags, bind to the Fab regions of Ig molecules outside their complementarity-determining regions. In addition, B cell SAgs can react with a substantial amount of a host's serum Igs by virtue of their ability to interact with many members of an entire variable heavy chain (VH) or variable light chain gene family. For example, SpA reacts with the Fabs of most human Igs using heavy chains from the VH3 gene family (VH3+). Members of this gene family are expressed on 30 to 60% of human peripheral B cells. We sought to determine whether the interaction of a B cell SAg with its reactive Igs can elicit immune complex-mediated tissue injury. Using the Arthus reaction in rabbits as an in vivo model of immune complex-mediated tissue inflammation, we demonstrated that untreated rabbits, which were administered SpA intradermally (i.d.), do not develop a cutaneous inflammatory response. However, when rabbits were pretreated i.v. with human IgG (hIgG), i.d. injections of SpA induced an inflammatory response with the classical histologic features of an Arthus reaction. To determine whether this Arthus-like response occurred via a B cell superantigenic mechanism, the rabbits were pretreated with VH3-depleted hIgG and then were administered SpA i.d. We found that the induction of a prominent inflammatory response by SpA was dependent upon the presence of VH3+ molecules in the hIgG pretreatment. These results provide compelling evidence that an interaction of the B cell SAg, SpA, with its reactive (VH3+) IgGs leads to an immune complex-mediated inflammatory response in vivo.

Animals↗

PubMed2001

Longitudinal analysis of T cells responding to tetanus toxoid in healthy subjects as well as in pediatric patients after bone marrow transplantation: the identification of identical TCR-CDR3 regions in time suggests long-term stability of at least part of the antigen-specific TCR repertoire.

To understand the nature of long-term Th immune responses, we investigated in the present study the TCRBV gene repertoire of CD4(+) T cells specific for the recall antigen tetanus toxoid (TT) in recipients of an allogeneic bone marrow transplantation (allo-BMT) at several time points after transplantation and in their BM donors. We observed that the TCR repertoire of TT-specific CD4(+) Th cells was heterogeneous, and differed between allo-BMT recipients and their respective donors. Some individuals, however, used similar TCR-complementarity-determining region (CDR) 3 motifs that could reflect recognition of and selection by similar promiscuous epitopes of TT. Longitudinal analysis of this TT-specific T cell response revealed that T cells with completely identical TCR were present at several time points after the first analysis in allo-BMT recipients, most probably reflecting long-term stability of at least part of the antigen-specific TCR repertoire. Similar stability of the TT-specific TCR repertoire in time was also noted in the allo-BMT donors. These observations reveal that within a given individual the dominant antigen-specific T cell clones persist in time in an otherwise diverse TT-specific CD4(+) T cell immune response.

Bone Marrow Transplantation↗

PubMed2004

T cell receptors recognizing type II collagen in HLA-DR-transgenic mice characterized by highly restricted V beta usage.

OBJECTIVE: To determine the T cell receptor (TCR) structure recognizing type II collagen (CII) in HLA-DR-transgenic mice, and to examine the role of T cells with certain V(beta)-chains in collagen-induced arthritis (CIA). METHODS: T cell hybridomas were established from DR1- and DR4-transgenic mice and selected for their responses to CII and CII peptide containing the T cell determinants. RNA was extracted and reverse transcribed into complementary DNA, which was then amplified using appropriate V(beta)- and V(alpha)-subfamily-specific primers. The polymerase chain reaction products were purified and directly sequenced. To determine the role of T cells with certain V(beta)-chains in CIA, V(beta)-subfamily-specific antibodies were administered and the development and characteristics of arthritis were determined. RESULTS: TCRs of 23 clonally distinct T cell hybridomas that were derived from DR1-transgenic mice and that were reactive to the CII peptide containing the immunodominant determinant were analyzed. These hybridomas predominantly used the TCR V(beta)14 and V(beta)8 gene segments (70% and 30%, respectively). The same restriction in V(beta) usage was also found in CII-reactive T cell hybridomas from DR4-transgenic mice. There was also restricted use of V(alpha) genes, although this was less marked than that of V(beta). In contrast, the hybridomas expressed a diverse third complementarity-determining region. Deletion of both V(beta)14-bearing and V(beta)8-bearing T cells significantly reduced the incidence and severity of CIA. CONCLUSION: These data demonstrate that DR1 and DR4 not only bind and present the same CII immunodominant peptide, but also stimulate a highly restricted subset of T cells.

Animals↗