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B Rapoport

Publications and source records attributed to B Rapoport.

At least 109 records · Page 6Linked to original sources
PubMed1994

Isolation and characterization of a monoclonal human thyroid peroxidase autoantibody of lambda light chain type.

Thyroid peroxidase (TPO) autoantibodies, a hallmark of human autoimmune thyroid disease, may have kappa or lambda light chains. Monoclonal human TPO autoantibodies with kappa light chains have previously been developed by cloning and expressing "combinatorial" libraries of immunoglobulin genes in bacteria. In the present study, an IgG1/lambda combinatorial library was generated from thyroid cDNA of a Graves' patient whose serum contained lambda TPO antibodies. Screening the bacteriophage library with 125I-TPO yielded one clone, TR1.41. The oligonucleotide sequence of TR1.41 was determined and the nature of its interaction with TPO was investigated. The affinity of TR1.41 for TPO is high (Kd approximately 10(-9) M), comparable to that of monoclonal kappa TPO autoantibodies derived from the same patient. The genes encoding the heavy and light chains of TR1.41 differ in a number of respects from the closest available germline genes. Such differences are consistent with somatic mutation in a high-affinity antibody. An important characteristic of TR1.41 is its interaction with the immunodominant domain on TPO recognized by approximately 80% of serum TPO autoantibodies. The frequency of TPO-specific F(ab) generated from the thyroid gland of patient TR was much lower for F(ab) with lambda light chains (1:150,000) than for F(ab) with kappa light chains (1:13,000). Despite this low frequency, the high affinity of TR1.41 and its recognition of the immunodominant region on TPO indicate that lambda autoantibodies of this type may represent an important constituent of the TPO autoantibody response in man. In conclusion, this is the first report on the molecular cloning and characterization of a thyroid autoantibody of lambda L chain type by the combinatorial library approach.

Amino Acid Sequence↗
PubMed1994

Recombinant thyroid peroxidase-specific autoantibodies. II. Role of individual heavy and light chains in determining epitope recognition.

Most thyroid peroxidase (TPO) autoantibodies in man recognize closely associated epitopes in two domains (A and B) on TPO. These epitopes were defined by recombinant monoclonal human autoantibodies expressed as antigen-binding fragments [F(ab)]. Only five heavy (H) and light (L) chain gene combinations encoded 34 F(ab), all of which have high affinity (Kd, approximately 10(-10) M) for TPO. We, therefore, investigated the roles of H and L chain genes in TPO domain recognition in two ways. First, we created hybrid F(ab) by forced recombination of H and L chain genes from 4 F(ab) recognizing the A or B domains. These hybrid F(ab) proteins, expressed in bacteria, bound extremely poorly (or not at all) to TPO, even at concentrations more than 100-fold higher than those required for detection of TPO binding by the original F(ab). Nucleotide sequencing of the cDNA as well as gel electrophoresis of the expressed proteins confirmed that poor hybrid F(ab) binding to TPO was not the result of cloning artifacts. Therefore, contrary to prevailing views on combinatorial libraries, we found no tolerance for H and L chain cross-combinations in high affinity TPO binding. These observations strengthen the likelihood that the H and L chain combinations from combinatorial libraries reflect those of TPO autoantibodies in vivo. In a second approach to examine the roles of H and L chains in TPO binding, we focused on three original F(ab) with similar L chains (encoded by KL012-like germline genes) and similar H chains (encoded by V1-3B-like germline genes), but different diversity (D) regions. All F(ab) bound predominantly to TPO domain A, as observed previously for a F(ab) with a KL012 L chain and a different H chain. Conversely, a F(ab) with a V1-3B-like H chain but a different L chain (A') bound to TPO domain B. These data indicate that the L chain plays a major role in defining TPO epitope recognition.

Amino Acid Sequence↗
PubMed1994

Recombinant thyroid peroxidase-specific autoantibodies. I. How diverse is the pool of heavy and light chains in immunoglobulin gene libraries constructed from thyroid tissue-infiltrating plasma cells.

Thyroid peroxidase (TPO) autoantibodies are a distinguishing feature of autoimmune thyroid disease. We have previously constructed immunoglobulin G heavy (H) and light (L) chain cDNA libraries from intrathyroidal B-cells. TPO-selected autoantibodies expressed by combined H and L chain libraries (combinatorial libraries) recognized a limited number of epitopes on TPO and used only a few of the many H and L chain variable region genes present in the genome (germline genes). One possible explanation for this restriction is a lack of diversity in the parental H and L chain gene libraries used to construct the combinatorial library. To address this issue, we determined the nucleotide sequences of randomly selected H and kappa L chain variable region genes from a pair of H and L chain libraries. The 12 H chain gene sequences analyzed were highly diverse, and none resembled the genes of TPO-selected autoantibodies. The sequences of 14 randomly selected kappa L chain genes were less diverse; 12 of 14 were closely related to the same germline gene (KL012) used by TPO-specific autoantibodies. However, we observed previously that only about 1 in 500 of the L chains in this library can pair with an H chain and bind TPO. We now find that, with 1 exception, the randomly selected KL012-like genes in the L chain library differ significantly from the antigen-specific KL012-like genes, particularly in the antigen-binding regions. In summary, the present data indicate that 1) the restricted number of H chain genes used by TPO-specific autoantibodies cannot be ascribed to limited H chain gene diversity in the parent library; and 2) L chains from combinatorial libraries (even when related to the same germline gene) cannot simply be regarded as plastic, or promiscuous, partners for high affinity antigen binding by a particular H chain.

Amino Acid Sequence↗
PubMed1994

Studies on homologous desensitization of the thyrotropin receptor in 293 human embryonal kidney cells.

It is well known that the TSH receptor (TSHR) undergoes homologous desensitization. That is, prolonged stimulation of thyroid cells with TSH attenuates the cAMP response to subsequent TSH stimulation. However, the existence of homologous desensitization of the recombinant TSHR expressed in nonthyroidal eukaryotic cells is controversial. In the present studies, therefore, we first investigated whether or not the TSHR was desensitized by TSH in 293 human embryonal kidney cells, a cell line in which the LH/CG receptor (LH/CGR) is reported to undergo homologous desensitization. The wild type (wt) TSHR and the wt-LH/CGR stably expressed in 293 cells bound to their respective hormones with high affinity and produced a dose-dependent intracellular cAMP response to hormone stimulation. Pretreatment of cells expressing the TSHR or the LH/CGR with their respective hormones attenuated the cAMP response to subsequent hormone stimulation without down-regulation of the receptors, demonstrating that the TSHR, as well as the LH/CGR, undergoes homologous desensitization in 293 cells. With this cell type expressing mutant TSHRs, we then studied some aspects of the molecular mechanism of TSHR desensitization and compared our data to those obtained with the beta-adrenergic receptor (beta-AR), which is widely regarded as the prototype for receptor desensitization. We cotransfected the wt-TSHR and a chimeric receptor consisting of the LH/CGR extracellular ligand binding domain with the TSHR transmembrane/cytoplasmic signal transducing region. These two receptors have distinct hormone specificities but share common signal regulatory mechanisms. We observed that, like the beta-AR, only hormone-occupied receptor is likely to be involved in homologous desensitization. On the other hand, studies with a truncated TSHR indicated that, in contrast to the beta-AR, the serine/threonine-rich region in the carboxyl two thirds of the cytoplasmic tail of the TSHR is not involved in homologous desensitization.

Animals↗
PubMed1994

Molecular cloning and characterization of genes for antibodies generated by orbital tissue-infiltrating B-cells in Graves' ophthalmopathy.

Graves' ophthalmopathy is a distressing autoimmune disease of unknown etiology. Analysis of the genes for antibodies secreted by orbital tissue-infiltrating plasma cells might provide insight into the pathogenesis of this disease. We, therefore, constructed an immunoglobulin heavy (H) chain and an immunoglobulin kappa light (L) chain cDNA library from the orbital tissue of a patient with active Graves' ophthalmopathy. Analysis of 15 H (IgG1) and 15 L (kappa) chains revealed a restricted spectrum of variable region genes. Fourteen of 15 variable kappa genes were about 94% homologous to the closest known germline gene, KL012. Thirteen of 15 H chain genes were 91% and 90% homologous to the closest germline genes, DP10 and hv1263, respectively. Remarkably, these germline genes also code for other autoantibodies to striated muscle (KL012) and thyroid peroxidase (KL012 and hv1263). These studies raise the possibility that particular germline genes may be associated with autoimmunity in humans. Further, the present study opens the way to identifying ocular autoantigens that may be the target of an humoral immune response.

Amino Acid Sequence↗
PubMed1994

Recombinant thyroid peroxidase autoantibodies can be used for epitopic "fingerprinting" of thyroid peroxidase autoantibodies in the sera of individual patients.

Four human monoclonal antibodies (SP1.4, WR1.7, TR1.8, and TR1.9) map the immunodominant region on thyroid peroxidase (TPO) recognized by autoantibodies in patients' sera. We used a pool of these monoclonal antibodies, expressed in bacteria as antigen-binding fragments [F(ab)], to compete for TPO autoantibody binding to radiolabeled TPO. The F(ab) inhibited TPO binding by 32 patients' sera by 82 +/- 14% (mean +/- SD), with a range from 51-100%. When each F(ab) was tested individually for its ability to compete for autoantibody binding to TPO, F(ab) TR1.8 was the most potent among the 32 sera. However, there was a wide spectrum of TPO binding inhibition when each serum was considered individually, thereby allowing an epitopic "fingerprint" to be drawn for the TPO autoantibodies in a patient's serum. There was a close association between the proportions of TPO autoantibodies to the TR1.8 and TR1.9 epitopes as well as between those to the SP1.4 and WR1.7 epitopes. These associations correspond to the previously described A and B epitopic domains in the TPO immunodominant region. No TPO epitope was observed to be associated with clinically apparent ophthalmopathy of Graves' disease, nor was there an association between TPO epitopes and patient age or sex. In summary, the present study on a large sample of sera with TPO autoantibodies indicates that by using TPO-specific F(ab) selected to cover all regions of the TPO immunodominant region, it is possible to obtain a TPO epitopic fingerprint for each serum. These data open the way to future studies directed at testing the hypothesis of disease-associated TPO epitope(s).

Autoantibodies↗
PubMed1994

Cell-mediated or humoral immunity in Graves' ophthalmopathy? Profiles of T-cell cytokines amplified by polymerase chain reaction from orbital tissue.

Whether Graves' ophthalmopathy is the results of a cell-mediated or humoral autoimmune response is controversial. T-Lymphocytes that regulate these two mechanisms, Th1 and Th2, respectively, are characterized by the profile of cytokines that they secrete. We, therefore, investigated the spectrum of T-lymphocyte cytokines expressed in Graves' orbital tissue by means of the polymerase chain reaction using reverse transcribed mRNA as template. From three Graves' thyroid tissues (positive controls), we obtained DNA products of the predicted size for the Th1 cytokines interferon-gamma (IFN gamma) and interleukin-2 (IL-2) as well as for Th2 cytokines IL-4 and IL-5. A signal for IL-10 (Th1 and Th2) was also detected. No cytokine signals were observed in peripheral blood (negative control). Despite the presence of T-cells (CD3 delta marker) in the orbital connective tissue/fat of all five patients studied as well as in orbital muscle from one of these patients, IFN gamma reverse transcribed mRNA was notably absent from these tissues. In contrast, IL-2, IL-5, and IL-10 cDNA was present in orbital tissues from one or more patients. Of particular importance, an IL-4 signal was detected in orbital connective tissue/fat of patients 6 and 7 as well as in muscle of patient 7. The balance between IL-4 and IFN gamma determines whether an immune response is predominantly humoral or cell mediated. Our finding of IL-4, but not IFN gamma, mRNA expression in orbital tissue supports a role, at least in some patients, for humoral autoimmunity in Graves' ophthalmopathy.

Aged↗
PubMed1994

Exclusion of two major areas on thyroid peroxidase from the immunodominant region containing the conformational epitopes recognized by human autoantibodies.

We have used a chimeric molecule between thyroid peroxidase (TPO) and myeloperoxidase (MPO) as well as new information on the three-dimensional structure of MPO to refine further our understanding of the location of the TPO-immunodominant region recognized by TPO autoantibodies in patients' sera. In TPO-MPO chimera A, the amino-terminal 146 amino acids of MPO substitute for the amino-terminal 121 amino acids of TPO. We performed fluorescence-activated cell sorter analysis of Chinese hamster ovary cells expressing TPO-MPO-A on their surface using four monoclonal human autoantibody F(ab) (WR1.7, TR1.8, TR1.9, and SP1.4) that define the immunodominant region. All four F(ab) recognized the TPO-MPO-A chimeric molecule to the same extent. In a second approach to refine the location on the TPO-immunodominant region, we compared the ability of the TPO autoantibody F(ab) to inhibit the binding of serum autoantibodies to the monomeric and dimeric forms of human TPO. The F(ab) inhibited equally (approximately 80%) the binding to the TPO monomer and dimer by autoantibodies in the sera of six individual patients. The present observations exclude two major regions of TPO from the autoantibody-immunodominant region, namely the amino-terminal 121 amino acids of the TPO extracellular domain and the contact region between the two TPO monomers. These findings together with previous data on the Mab47/C21 region of TPO and the recently elucidated 3-dimensional structure of highly homologous MPO, narrow, by a process of exclusion, the site on TPO comprising the immunodominant region. The data provide further support for the thesis, still controversial, that the majority of TPO autoantibodies recognize the native molecule.

Animals↗
PubMed1993

High affinity, thyroid-specific human autoantibodies displayed on the surface of filamentous phage use V genes similar to other autoantibodies.

Autoantibodies to thyroid peroxidase (TPO) are characteristic of thyroid inflammation in autoimmune thyroid disease. We have used the phage display, H and L chain combinatorial cDNA library approach to clone, from thyroid-infiltrating B cells, six new human Fab autoantibodies with high affinities (approximately 10(-10) M) for TPO. This library, in the pComb3 vector, was screened with viable, stably transfected Chinese hamster ovary cells expressing human TPO on their surface. The H and L chain genes in the six TPO-specific Fab were similar, but not identical, to those encoding Fab previously isolated from the same library by screening bacteriophage plaques in the Immunozap vector with purified TPO. The TPO-specific VK genes isolated with the phage display system are closer to germline than those obtained with Immunozap. Essentially all the V kappa isolated with pComb3 were 99 or 100% homologous with the germ-line genes KL012 and A3 that also code for low affinity systemic autoantibodies. There are two important implications of the study. First, the phage display system can be used with impure Ag to generate high affinity autoantibodies. This finding opens the way to cloning autoantibodies against other autoantigens, not previously possible with the bacteriophage lambda approach because of the lack of purified Ag. Second, germ-line L chain genes can code for very high affinity antibodies.

Amino Acid Sequence↗
PubMed1993

T cells involved in human autoimmune disease are resistant to tolerance induction.

Deletion of potentially self-reactive T-cell clones during intrathymic development provides an important mechanism of preventing autoreactivity. However, some potentially damaging cells may escape this process. Recent evidence suggests that these cells may be rendered 'anergic', that is, nonresponsive to Ag, in the absence of cell death. Such a mechanism may be particularly important in maintaining tolerance to organ-specific self Ag that are not expressed in the thymus. If so, the emergence of T cells resistant to anergy induction might be expected to result in autoimmune disease. It has previously been shown that anergy can be induced in human T cells in vitro by exposure to specific target peptide or bacterial enterotoxins in the absence of Ag-presenting cells. We have recently defined the antigenic specificity of multiple T-cell clones present at the site of a human organ-specific autoimmune disease, Graves' thyroiditis (Graves disease). In the current work, thyroid-derived T cells recognizing residues 535-551 of the thyroid tissue-specific enzyme, TPO3 have been used to examine whether cells actively involved in the autoimmune process are resistant to anergy induction, as defined by anergy induction with in vitro systems. Two systems were used. First, supraimmunogenic concentrations of peptide 535-551 (up to 1 mg/ml) failed to significantly anergize these T cells in the absence of APC. In addition, the bacterial enterotoxin SED that could stimulate these T cells in the presence of APC, failed to induce anergy when APC were not present. T cells from the peripheral blood of the same individual, in contrast, were anergizable with bacterial enterotoxins, using the same protocol. These results suggest that thyroid-infiltrating autoantigen-reactive T cells are refractory to induction of anergy, and the possibility is raised that this deficiency may be of importance in the development of autoimmunity.

Amino Acid Sequence↗
PubMed1993

Lack of promiscuity in autoantigen-specific H and L chain combinations as revealed by human H and L chain "roulette".

Individual H or L chains from a human autoantibody were used to search for other L or H chains that could form antigen-binding fragments, Fab, with the same specificity. The parent Fab (SP1.2) exhibits high affinity binding for thyroid peroxidase (TPO), a 107-kDa protein that is the major autoantigen in human autoimmune thyroiditis. This autoantibody "roulette," performed by using Ig H and L chain gene libraries expressed in bacteria, increased the frequency of TPO-binding clones in the new libraries. However, the frequency was still much lower than would be the case if promiscuous combinations with a variety of H or L chains were compatible with specific Ag binding. Nucleotide sequence analysis of the H and L chains of the new TPO-binding clones revealed even more restriction. Thus, with the SP1.2 H chain, all 11 new Fab utilized L chains from the same V kappa 1 family germline gene as SP1.2 itself. Similarly, five of six H chains "captured" by the SP1.2 L chain were very closely related to the SP1.2 H chain. However, one totally different H chain was isolated: SP4.6 has a VH region that differs substantially from that of SP1.2. SP4.6 also has a distinct D region, uses a different JH, and, unlike SP1.2, which is an IgG1, belongs to subclass IgG4. The affinities for TPO of SP4.6 (with the different H chain) and SP1.20 (which had the least mutated L chain germline gene) were similar to that of SP1.2 (approximately 10(-10) M). As expected, the SP1.2 and SP1.20 Fab, which have the same H chain and closely related L chains, bound to the same domain on TPO. However, a similar domain on TPO was recognized by both SP4.6 and SP1.2, despite the fact that their V, D, and J regions are quite different. This observation raises the possibility that the L chain is critical in defining epitope specificity, even in the presence of completely different D regions and nonidentical VH regions.

Amino Acid Sequence↗
PubMed1993

Autoantibodies in the sera of patients with autoimmune thyroid disease recognize a secreted form of human thyroid peroxidase generated in a baculovirus system.

We used a baculovirus vector to express the cDNA for a truncated (amino acid residues 1-848), secreted form of thyroid peroxidase (TPO) in Sf9 insect cells. Immunoreactive TPO was detected in pooled conditioned media from 10 clones using polyclonal TPO autoantibodies in the sera of patients with autoimmune thyroid disease. As a further test of TPO immunogenicity, the pooled media completely inhibited autoantibody binding to antigen. We used an ELISA to compare autoantibody reactivity to insect cell-derived TPO and TPO antigen produced by Chinese hamster ovary (CHO) cells, the standard form of antigen in present use. In a study of 22 TPO antibody-negative sera and 24 sera with different TPO autoantibody potencies, there was a highly significant correlation (r = 0.977; p < 0.001) in OD values obtained with TPO from the two different sources. The highest producing baculovirus clone generated 8.5 micrograms TPO/ml of conditioned medium, nearly 10-fold higher than previously achieved with stably transfected Chinese hamster ovary cells. Baculovirus-derived, soluble TPO therefore is an excellent source of recombinant TPO in further studies to examine the precise B cell epitopes for human autoantibodies.

Animals↗
PubMed1993

Thyrotropin receptor autoantibodies recognizing two different epitopes on the TSH receptor: lack of relationship to patient age, sex, and ophthalmopathy.

The existence of two populations of stimulatory TSH receptor autoantibodies against different epitopes raises the possibility of a link between one type of autoantibody and the clinical manifestations of Graves' disease. To test this hypothesis, serum immunoglobulins from 48 patients with Graves' disease were assayed for TSH binding inhibition (TBI) activity with two different recombinant TSH receptor variants (TSH-LHR-6 and TSH-LHR-6-A1) expressed on Chinese hamster ovary cells. The activity of 27 of the 48 patients' immunoglobulin samples was significantly less (difference in TBI value of 9% or greater) with chimera 6-A1 than with chimera 6. No immunoglobulin sample had significantly greater TSH binding inhibitory activity with chimera 6-A1 than with chimera 6. Sensitivity to the 6-A1 epitope substitution did not correlate with patient age, sex, or the presence or absence of hyperthyroidism. Further, there was no segregation of individual patients with TSH receptor autoantibodies with 6-A1 epitope sensitivity in terms of the past or present occurrence of ophthalmopathy, including the severity (total eye score), clinical activity, duration, and type of therapy. These data indicate that recognition by autoantibodies of the 6-A1 epitope on the TSH receptor is not associated with the ophthalmopathy of Graves' disease. However, the possibility cannot be excluded that other functional (or even nonfunctional receptor autoantibodies that are not detectable by present assays) may still play a role in the pathogenesis of Graves' ophthalmopathy.

Adult↗
PubMed1993

Human organ-specific autoimmune disease. Molecular cloning and expression of an autoantibody gene repertoire for a major autoantigen reveals an antigenic immunodominant region and restricted immunoglobulin gene usage in the target organ.

The most common organ-specific autoimmune disease in humans involves the thyroid. Autoantibodies against thyroid peroxidase (TPO) are present in the sera of virtually all patients with active disease. We report the molecular cloning of the genes for 30 high-affinity, IgG-class human autoantibodies to TPO from thyroid-infiltrating B cells. Analysis of the putative germline genes used for the TPO human autoantibodies suggests the use of only five different H and L chain combinations involving four H chains and three L chains. In addition, the same combination of H and L chains was found in multiple patients. The F(ab) proteins expressed by these genes define two major, closely associated domains (A and B) in an immunodominant region on TPO. These A and B domains contain the binding sites of approximately 80% of IgG-class TPO autoantibodies in the sera of patients with autoimmune thyroid disease. The present information permits analysis, not previously possible, of the relationship between autoantibody H and L chain genes and the antigenic domains on an autoantigen. Our data, obtained using target organ-derived autoantibodies, indicate that there is restriction in H and L chain usage in relation to the interaction with specific antigenic domains in human, organ-specific autoimmune disease.

Antibody Affinity↗
PubMed1993

Human thyroid peroxidase-myeloperoxidase chimeric molecules: tools for the study of antigen recognition by thyroid peroxidase autoantibodies.

We constructed seven chimeric molecules in which sequential segments in the cDNA for thyroid peroxidase (TPO) were replaced with the homologous regions of myeloperoxidase (MPO) cDNA. The sizes of the translated cDNA segments A through G ranged from 23-175 amino acid residues in length. The TPO-MPO cDNA chimeras, inserted into an eukaryotic expression vector, were stably transfected into Chinese hamster ovary cells. Protein expression was examined by immunoblotting under reduced/denaturing conditions with a murine monoclonal antibody to denatured wild-type TPO. Expression (at a low level) was confirmed for TPO-MPO chimeras A, B, F, and G. The amino acid substitutions in TPO-MPO-C eliminate the monoclonal antibody epitope, and this chimera, therefore, provides a negative control. TPO-MPO-D and TPO-MPO-E did not generate detectable levels of protein. To study TPO autoantibody interaction with native protein, we performed fluorescence-activated cell sorter analysis using intact Chinese hamster ovary cells stably transfected with the wild-type and TPO-MPO chimeric cDNAs. Of the chimeras, only cells transfected with TPO-MPO-A (N-terminal 146 amino acids of MPO substituted for the N-terminal 121 amino acids of TPO) were recognized by TPO autoantibodies, although to a lesser degree than cells expressing wild-type TPO. In conclusion, the present data indicate that TPO autoantibodies can interact with TPO molecules in which the amino-terminus is replaced with the homologous MPO prosequence region, not normally present in mature MPO. Our study provides a foundation for designing future TPO mutants that may be of value for characterizing disease-associated B-cell epitopes in autoimmune thyroid disease.

Animals↗
PubMed1993

The immunodominant region on human thyroid peroxidase recognized by autoantibodies does not contain the monoclonal antibody 47/c21 linear epitope.

We performed studies to determine whether the binding sites on thyroid peroxidase (TPO) of immunoglobulin antigen binding fragments (Fabs) representing more than 80% of the human autoantibody repertoire overlap with the binding site of monoclonal antibody (Mab) 47, the only Mab whose partial epitope has been defined at the amino acid level (residues 713-721). We also investigated whether these Fabs preferentially recognize native or denatured TPO. None of the Fabs, when bound to radiolabeled TPO, interfered with the ability of Mab 47 to bind to this material. In enzyme-linked immunosorbent assay experiments, the binding of TPO autoantibody Fabs SP1.5, WR1.7, TR1.8, and TR1.9 was greatly diminished by denaturation of TPO. In contrast, binding of Mab 47 was higher to denatured TPO than to intact TPO. Our studies indicate that the Mab 47/C21 epitope lies outside the immunodominant region on TPO. Further, the data confirm that the majority of epitopes for TPO autoantibodies are highly conformational (dependent on the three-dimensional structure of the native protein). Native TPO will be needed to complete the mapping of the epitopes for TPO autoantibodies as well as to determine the amino acids at the autoantibody-antigen-binding sites.

Animals↗