CTLA-4 gene polymorphism at position 49 in exon 1 reduces the inhibitory function of CTLA-4 and contributes to the pathogenesis of Graves' disease.

Activation of T cells requires at least two signals transduced by the Ag-specific TCR and a costimulatory ligand such as CD28. CTLA-4, expressed on activated T cells, binds to B7 present on APCs and functions as a negative regulator of T cell activation. Our laboratory previously reported the association of Graves' disease (GD) with a specific CTLA-4 gene polymorphism. In theory, reduced expression or function of CTLA-4 might augment autoimmunity. In the present study, we categorized autoimmune thyroid disease patients and normal controls (NC) by genotyping a CTLA-4 exon 1 polymorphism and investigated the function of CTLA-4 in all subjects. PBMCs and DNA were prepared from GD (n = 45), Hashimoto's thyroiditis (HT) (n = 18), and NC (n = 43). There were more GD patients with the G/G or A/G alleles (82.2% vs 65.1% in NC), and significantly fewer patients with the A/A allele (17.8% vs 34.9% in NC). In the presence of soluble blocking anti-human CTLA-4 mAb, T cell proliferation following incubation with allogeneic EBV-transformed B cells was augmented in a dose-dependent manner. Augmentation induced by CTLA-4 mAb was similar in GD and NC (GD, HT, NC = 156%, 164%, 175%, respectively). We related CTLA-4 polymorphism to mAb augmentation of T cell proliferation in each subgroup (GD, HT, NC). Although PBMC from individuals with the G/G alleles showed 132% augmentation, those with the A/A alleles showed 193% augmentation (p = 0.019). CTLA-4 polymorphism affects the inhibitory function of CTLA-4. The G allele is associated with reduced control of T cell proliferation and thus contributes to the pathogenesis of GD and presumably of other autoimmune diseases.

Evaluating the role of Th0 and Th1 clones in autoimmune thyroid disease by use of Hu-SCID chimeras.

To study the role of Th0 and Th1 cells in autoimmune thyroid disease, thyroid tissues from patients with Graves' disease (GD), Hashimoto's thyroiditis (HT), and colloid nodular disease were xenografted into SCID mice, followed by ip injection of peripheral blood mononuclear cells (PBMC), T cell lines, and T cell clones (TCC). The antigen-specific TCC reactive to TSH receptor (TSH-R), thyroid peroxidase (TPO), or thyroglobulin (Tg), and their respective peptides, were classified into Th0 (secreting IL-4 and/or IL-5 and IFN-gamma) and Th1 (secreting IFN-gamma) according to their cytokine profile. Engraftment of autologous or HLA-matched allogeneic CD4+ thyroid-specific clones with Th0 or Th1 phenotypes induced the production of total IgG and thyroid-specific autoantibodies by B cells present in xenografted thyroid tissues. TSH-R-specific clones mainly enhanced thyroid-stimulating antibodies (TSAb) production, while clones reactive to TPO and Tg increased the synthesis of TPO and Tg autoantibodies. Total IgG production, but not TSAb, was also stimulated by PBMC and TSH-R lines. TSAb correlated with the viability and hyperplasia of thyroid follicles, but not with the serum T3 levels, which were normal. Thyroid tissue viability was maintained or increased by antigen-specific Th0 clones, and decreased by Th1 clones reactive to TSH-R or TPO. Thyroid lymphocytic infiltration was variable; however, Th0 and Th1 clones from HT patients caused high degree of lymphocytic infiltration compared to the control groups. These results demonstrate for the first time that T cells clones reactive to specific epitopes of TSH-R, TPO, or Tg can generate antibody-mediated and/or cell-mediated responses in the xenografted thyroid tissue microenvironment. Such effects depend on clonal specificity, HLA class II restriction, and cytokine profile of the clone. Th0 clones reactive to TSH-R stimulate both total IgG production and TSAb in SCID mice engrafted with thyroid tissue from GD patients. Th0 and Th1 clones specific for TPO and Tg also function as helper T cells, stimulating total IgG synthesis and autoantibodies against TPO and Tg. Th1 clones may also cause tissue destruction in GD and HT.

Thyrotropin-receptor and thyroid peroxidase-specific T cell clones and their cytokine profile in autoimmune thyroid disease.

We studied the cytokine profile and the immune responses to thyroid antigens of specific T cell clones (TCC) isolated from patients with Hashimoto's thyroiditis (HT) and Graves' disease (GD). Antigen-specific TCC were reactive to thyroid peroxidase (TPO), thyroglobulin (Tg) or human recombinant TSH-receptor extracellular domain (TSH-R), and/or their respective peptides. Of the 43 clones derived from HT patients, 65% were reactive to TPO, and 59% of the 32 clones derived from GD patients were reactive to TSH-R. TPO epitopes 100-119 and 625-644 were recognized by 75% of HT-derived clones, whereas TSH-R epitopes 158-176, 207-222, and 343-362/357-376 were recognized by 85% of GD-derived TCC. The TCC were classified according to their cytokine profile into T helper cell (Th)0 [secreting interleukin (IL)-4, IL-5, interferon (IFN)-gamma], Th1 (secreting IFN-gamma) and Th2 (secreting IL-4 and/or IL-5). Tumor necrosis factor-beta and IL-10 were produced by all subsets. The specific TCC were predominantly Th1-like cells in HT, and were Th0- and Th1-like cells in GD. Fifty three percent of Th0 clones were derived from GD patients and were reactive to TSH-R, whereas 50% of Th1 clones were derived from HT patients and were reactive to TPO or Tg. Most Th2 clones (82%) were reactive to TPO and were established from peripheral blood. All these clones produced IL-5, and 64% produced IL-4 and IL-10. Interestingly, IFN-gamma was highly produced by TPO- or Tg-specific clones established from HT thyroid tissue. These results confirm at the clonal level our previous studies regarding T cell epitopes on TPO and TSH-R molecules and support the concept that immunodominant T cell epitopes are located on amino acid residues 100-119 and 625-644 of TPO in HT and amino acid residues 158-176, 207-222 and 343-362/357-376 of TSH-R in GD. Our studies also demonstrate that thyroid-specific T cells can be classified into Th0, Th1, and Th2 subsets. TPO- or Tg-specific clones with Th1 phenotype appear to be involved in the pathogenesis of HT, mediating thyroid tissue destruction, whereas TSH-R clones with Th0 phenotype may induce thyroid-stimulating autoantibodies in GD.

Immunosuppression of thyroiditis.

Immunization of mice with 50 micrograms human thyroglobulin (TG) in complete Freund's adjuvant leads to histological thyroiditis; production of IgG, IgA, and IgM anti-TG antibodies; and in vitro proliferative responses after incubation of lymphocytes with TG. Oral administration of 500 micrograms TG at four intervals before Tg immunization and once afterward causes up to 80% suppression of these responses. The effect is antigen specific and dose dependent. Feeding TG after immunization produces a 40% reduction in responses. We wished to define the mechanism of this antigen-specific oral tolerization. Popliteal lymph nodes (PLN) of orally tolerized animals (T) are reduced in size compared to those in immunized (I) animals not fed TG. PLN and mesenteric lymph nodes (MLN) of I animals produce interleukin-2 (IL-2) and interferon-gamma (IFN gamma) after in vitro incubation with TG, typical of an inflammatory immune response. PLN and MLN of tolerized animals do not proliferate in response to antigen, do not produce IL-2 or IFN gamma, but do not produce the cytokines IL-4 and transforming growth factor-beta (TGF beta). Mixing in vitro of spleen cells from T and I animals causes a reduction in the immune response when incubated with TG, but no reduction in response to purified protein derivative (PPD) (the antigen in complete Freund's adjuvant). When T splenocytes are incubated with TG and PPD together, the response to TG and PPD is suppressed. Partially purified CD8+ cells from tolerized animals produce IL-4 and TGF beta after exposure to human TG and induce suppression, whereas partially purified CD4+ cells produce IL-2 and IFN gamma and do not cause suppression. MLN cells do not proliferate in response to antigen, but do produce inhibitory cytokines. T animals appear to shift the immune response from a Th-1 helper cell subset response to a Th-2 helper cell immunosuppressive response. In this model, oral tolerization produces a dramatic reduction in the immune response. Exposure of MLN to oral TG appears to cause the production of regulatory cells that migrate to spleen and PLN. In vitro studies demonstrate that on exposure to antigen, these regulatory cells produce IL-4 and TGF beta, which suppress all aspects of specific immune responsiveness and nonspecifically suppress other ongoing immune responses (bystander effect). Oral tolerization may include some element of T cell deletion or anergy. This model defines an experimental system with possible relevance to immunosuppression of human autoimmune thyroid disease.

Expression of thyroid peroxidase in EBV-transformed B cell lines using adenovirus.

Thyroid peroxidase (TPO) is thought to be one of the pathological antigens in Hashimoto's thyroiditis. Epstein-Barr virus-transformed B cell lines (EBVL) can be used for antigen-presenting cells and target cells of cytotoxic T cells. To develop a model for endogenous TPO presentation in EBVL, we constructed a recombinant adenovirus carrying the TPO gene driven by the cytomegalovirus promoter (Ad5-TPO). Enzymatically active human TPO could be expressed in COS cells using Ad5-TPO. the peroxidase activity of the membrane extract from Ad5-TPO-infected COS cells was approximately 6 times higher than that from stably transfected TPO expressing CHO cells. TPO protein expression in the EBVL was analyzed by Western blotting technique. A band at approximately 110 kDa characteristic of hTPO was detected in EBVL infected with Ad5-TPO. hTPO expression in EBVL induced with adenovirus should facilitate understanding of T cell immunity to TPO in patients with autoimmune thyroid diseases.

Graves' disease in severe combined immunodeficient mice.

Graves' disease (GD) is an autoimmune thyroid disorder involving an antibody (TSAb) directed against the TSH receptor (TSHR) producing thyroid stimulation. We have developed an animal model of GD by engrafting peripheral blood mononuclear cells or T cell lines plus autologous thyroid tissue into severe combined immunodeficient (SCID) mice. We xenografted Graves' thyroid tissue from six patients into six groups of SCID mice. Autologous PBMC and T cell lines reactive to recombinant human TSHR extracellular domain and non-TSHR lines were injected ip into the designated groups. In some of the studies, thyroid tissue was irradiated with 2000 rads before xenografting. Irradiation of xenografts induced thyroid tissue damage and release of thyroid antigens and hormones. Mice reconstituted with peripheral blood mononuclear cells or nonspecific T cell lines did not simulate GD. However, we achieved production of TSAb, elevation of serum T3, and TSAb-dependent survival and function of human Graves' thyroid tissue in SCID mice reconstituted with TSHR-specific T cell lines. We reconstituted SCID mice with PBMC and TSHR-specific T cell lines that recognized TSHR peptide 158-176. This may be in vivo evidence of the importance of peptide 158-176 as an immunodominant epitope on the TSHR extracellular domain.

Suppression of development of experimental autoimmune thyroiditis by oral administration of thyroglobulin.

Experimental autoimmune thyroiditis (EAT), which to some extent represents an experimental model of human chronic lymphocytic thyroiditis, is an organ-specific autoimmune disease characterized by autoantibody production to thyroid antigens (Ag) and mononuclear infiltration of the thyroid gland. EAT induced by immunization with human thyroglobulin (hTG) with Freund's adjuvant in CBA/J (H-2K) mice is associated with prominent B and T cell responses. We report that oral administration of hTG effectively reduces the immune responses in EAT in mice in an Ag-specific manner. Both cellular and humoral immune responses are reduced in a dose-dependent manner. Histological evidence of disease is dramatically reduced. Suppression of the immune responses is seen 2 weeks after Ag challenge, with partial inhibition of proliferative and antibody responses. Six weeks after immunization, further inhibition is observed of both T and B cell responses. Hyporesponsiveness of T and B cell reactivity is seen only to hTG; T and B cell responses to other immunogens are not affected, including purified protein derivative and the nonrelated Ag BSA. This model may provide the basis for immunotherapy of autoimmune thyroid diseases in man.

Proliferative responses of T-cells to thyroid antigens and synthetic thyroid peroxidase peptides in autoimmune thyroid disease.

We studied the immune responses of 33 patients with autoimmune thyroid disease (AITD; including 17 with Hashimoto's thyroiditis and 16 with Graves' disease), 5 patients with non-AITD, 12 control subjects (CS), and 2 subjects with a family history of autoimmunity to the main thyroid antigens. These antigens included thyroid peroxidase (TPO), thyroglobulin (Tg), TSH receptor (TSH-R), and 13 overlapping TPO peptides. T-cell lines (TCL) were isolated from peripheral blood mononuclear cells (PBMC) after incubation with TPO, Tg, or a protein derivative of tuberculin (PPD). PBMC and TCL were used in a 3- to 5-day microproliferation assay. Peripheral lymphocytes from most AITD patients responded with a stimulation index of 3 or more to TPO, Tg, and/or TSH-R (60-88%) as well as to two or more TPO peptides. Lymphocytes from 3 of 5 patients with non-AITD and 2 subjects with a family history of autoimmunity were also reactive to thyroid antigens. TPO TCL showed a high proliferative response to TPO and its peptides, whereas Tg TCL were less reactive and PPD TCL were nonreactive to these antigens. Six of the 13 peptides tested produced highly significant stimulation in PBMC (CS, 0-17%; AITD, 60-92%) and TPO TCL (73-91%). The amino acid sequences of these putative epitopes were located in TPO regions 100-119, 211-223, 261-275, 420-434, 625-644, and 882-901. These results demonstrate T-cell responses to the main thyroid antigens, including TPO, Tg, and TSH-R, and confirm the heterogeneity of TPO T-cell epitopes in patients with AITD. Amino acid residues 100-119, 420-434, 625-644, and 882-901 are the most common sites recognized by TPO TCL, indicating that they may be immunogenic epitopes in AITD.

T-cells recognize multiple epitopes in the human thyrotropin receptor extracellular domain.

In Graves' disease (GD), the TSH receptor (TSHR) is believed to be the major target of an autoimmune response. T-Lymphocytes regulate the immune system. To assess the interaction of T-cells with TSHR in the pathogenesis of GD, we tested the T-cell response of peripheral blood mononuclear cells and T-cell lines to the recombinant human TSHR extracellular domain (rhTSHR-ECD) and 31 synthetic peptides corresponding to the entire TSHR-ECD in 20 patients with GD, 8 patients with Hashimoto's thyroiditis, 7 with colloid nodular goiter (CNG), and 20 normal controls. Comparing patients from different groups with normal subjects, there was a significant response to rhTSHR-ECD and thyroglobulin in GD patients (P < 0.001) and HT patients (P < 0.05), but not in CNG patients (P > 0.1). All 20 patients with GD responded to at least one peptide. The reactivity in GD patients was heterogeneous and spanned the entire TSHR-ECD. However, the reactivity was significantly different from that in controls for peptide regions 44-88, 119-176, 227-263, and 343-376, and the stimulation index (SI) values were significantly different for peptides 272-291 and 301-320. Significant differences were confined to peptides 158-176 and 343-362 and the region 227-263 for comparison of the number of positive responses in patients and controls to individual peptides. Forty-six percent of human leukocyte antigen-DQA1 0501 allele-positive Graves' patients responded to peptides 158-176 and 248-263 (SI = 3 or more) compared to 14% of allele-negative patients. In HT and CNG patients, the response was mainly to peptides in the carboxy-terminal half of the TSHR-ECD. Concordance of the reactivity in T-cell lines and peripheral blood mononuclear cells was observed in 36% of direct comparisons in GD. Eighty-five percent and 90% of GD patients were positive for microsomal antibody and TSHR antibody, respectively, and 59% of microsomal antibody-positive and 67% of TSHR antibody-positive patients responded to rhTSHR-ECD (SI = 2 or more). However, there was no significant correlation between antibody-positive patients and reactivity to specific peptides. Using multiple criteria to define immunodominance, peptides 158-176, 237-252, 248-263, and 343-362 seem to be important epitopes and may be critical for T-cell triggering in GD.

T-cell reactivity to recombinant human thyrotropin receptor extracellular domain and thyroglobulin in patients with autoimmune and nonautoimmune thyroid diseases.

Grave's disease and Hashimoto's thyroiditis are common organ-specific disorders characterized by an immune response toward a number of thyroid proteins, including TSH receptor (TSHR), thyroid peroxidase, and thyroglobulin (Tg). Although considerable progress has been made in understanding and mapping the autoantibody response to TSHR, much less is known about recognition of TSHR by pathogenic T-cells in human disease. To identify such reactions, we analyzed the T-cell proliferative responses of peripheral blood lymphocytes (PBMC) to human recombinant TSHR extracellular domain (hrecTSHR-ECD amino acids 19-417) expressed in Escherichia coli and to Tg. Forty-two patients with autoimmune thyroid disease (AITD), 13 patients with non-AITD, and 20 normal subjects were studied. PBMC from 40% of patients with AITD and 46% of patients with non-AITD reacted significantly to hrecTSHR-ECD. The reactivity to Tg was less than that to TSHR-ECD in both groups. Five percent of normal subjects showed a response to hrecTSHR-ECD and none to Tg. TSHR-specific T-cell lines were developed in 16 of 26 AITD patients and 3 of 10 non-AITD patients. CD8-positive T-cell depletion from PBMC of 8 patients with AITD by the indirect panning method did not enhance the reactivity to hrecTSHR-ECD, except in 1 patient. We conclude that TSHR-specific T-cells are present in the circulation of patients with AITD and are presumably involved in the pathogenesis of thyroid autoimmunity. The lower, but positive, reactivity to hrecTSHR-ECD found in patients with non-AITD was unexpected and may be related to lymphocytic infiltrates in the thyroid of 7 of the 11 patients.

Proliferative responses of peripheral blood mononuclear cells from patients with Graves' disease to synthetic peptides epitopes of human thyrotropin receptor.

In Graves' disease thyrotropin receptor (TSH-R) autoantibodies cause hyperthyroidism. Production of TSH-R autoantibodies must be controlled by specific T cells. In this study we investigated T cell responses to 33 peptides corresponding to the sequence of the extracellular domain of human TSH-R. Peripheral blood mononuclear cells (PBMC) from 12 patients with Graves' disease and 9 healthy subjects were cultured with peptides for 3 days. The proliferative responses of PBMC were analyzed by measurement of [3H]thymidine incorporation. A stimulation index (SI; mean cpm in the presence of peptide/mean cpm in culture medium alone) of more than 3 was considered a positive response. When PBMC were stimulated with a pool containing all synthesized peptides, the mean SI of patients was significantly higher than that of controls (4.50 +/- 3.95 vs. 1.44 +/- 0.60; p < 0.05). When PBMC were cultured with individual peptides, PBMC from patients responded predominantly to two peptides, corresponding to sequence segments 152-157 (5 patients) and 207-222 (4 patients). No PBMC from controls responded to these two peptides. There was no clear correlation between the HLA-DR or HLA-DQ genotype and the stimulatory sequence segments. These results suggest that (a) TSH-R-specific T cells are present in peripheral blood of patients with Graves' disease, and (b) sequence segments 152-157 and 207-222 may be T cell epitopes of the human TSH-R in Graves' disease.

Human histocompatibility leukocyte antigen-DQA1*0501 allele associated with genetic susceptibility to Graves' disease in a Caucasian population.

Graves' disease (GD) is an autoimmune disease of the thyroid gland. Genes of, or closely associated to, the HLA complex are assumed to contribute to the genetic predisposition to GD. We have previously reported an increased frequency of HLA-DR3/DQ2 in Caucasian patients with GD, and recently the importance of Dw24 encoded by DRB3 gene has been suggested. To further investigate the associations of GD and these genes, 94 unrelated patients with GD and 75 control subjects were typed for HLA-DRB3, -DRB1, -DQA1, and -DQB1, using sequence-specific oligonucleotide probes to analyze polymerase chain reaction amplified DNA (PCR-SSO). Three findings emerged from these studies. 1) The frequency of subjects positive for DQA1*0501 (GD, 73.4% vs. control 42.7%, P = 0.0001, Pc < 0.001, RR = 3.71) was significantly increased among patients. The frequency of DR3 (GD, 34.0% vs. control 17.3%, P = 0.0146, RR = 2.46), which is in tight linkage disequilibrium with DQA1*0501, was also increased; however, it was not significant when the P value was corrected for the number of antigens tested. Neither DQB1 nor DRB3 alleles were significantly increased in frequency. 2) After exclusion of DR3-positive subjects, DQA1*0501 was still significantly increased (GD, 59.7% vs. control 30.6%, P = 0.0012, Pc < 0.01, RR = 3.35) among patients. 3) The distributions of Dw24 and Dw25,26 (Dw25 or Dw26) did not differ between patients and controls on either DR3 positive or negative groups. These findings suggest that DQA1*0501, or a closely associated unknown gene, confers susceptibility to GD, while Dw24 is not directly involved. The importance of DR3, however, remains to be elucidated, because of the fixed linkage with DQA1*0501.

Proliferative responses of peripheral blood mononuclear cells from patients with autoimmune thyroid diseases to synthetic peptide epitopes of human thyroid peroxidase.

In order to analyze T cell epitopes of human thyroid peroxidase (TPO), 60 peptides based on the sequence of TPO were synthesized and used as antigens in a peripheral blood mononuclear cell (PBMC)-proliferation assay. PBMCs were obtained from 19 patients with Graves' disease, 19 patients with Hashimoto's thyroiditis, and 24 normal subjects. Significant proliferation of PBMC to these peptides occurred only among the autoimmune thyroid disease (AITD) patients, whereas normal subjects did not respond to any of the peptides with a stimulation index over 2. Many peptides induced isolated positive responses and eight produced stimulation of PBMCs from multiple patients on comparison to control PBMC responses. To confirm the significance of reactivity to the peptides PBMCs from four patients were studied on two occasions, and the proliferative responses found to be reproducible. Four peptides, designated according to the amino acid sequence as p110-129, p211-230, p842-861, and p882-901, stimulated patients' PBMCs in a dose-dependent manner. The optimal concentration was 10 micrograms/ml. An anti-HLA-DR monoclonal antibody directed against a monomorphic determinant of the DR molecule was able to block the responses. A significant correlation was found between the PBMC responses to these peptides and responses to microsomal antigen (McAg)/TPO. These data suggest that four peptides corresponding to the amino acid sequences 110-129, 211-230, 842-861 and 882-901 are T cell epitopes of TPO.

The regulatory role of human helper T-cell clones on antithyroid antibody production by peripheral B-cells.

The helper effects of thyroid antigen-specific T-cell clones (TCC) on antibody production by peripheral B-cells were studied and compared with similar effects of self major histocompatibility complex II (MHC-II)-reactive TCC as well as uncloned CD4+ cells. Ten TCC were derived from thyroid tissue or peripheral blood mononuclear cells (PBMC) in patients with Graves' disease. Uncloned CD4+ cells were also obtained from PBMC in patients with autoimmune thyroid disease. All TCC were CD3+/CD4+. B-Cells from patients with mainly high serum levels of microsomal antibodies (McAb) were cultured alone and with either TCC or uncloned CD4+ cells in the presence or absence of thyroid antigens [microsomal antigen/thyroid peroxidase (McAg/TPO) and thyroglobulin (Tg)] or pokeweed mitogen (PWM). Total immunoglobulin G (IgG) and specific thyroid antibodies were measured by enzyme-linked immunosorbent assay. Self MHC-II-reactive TCC induced B-cell production of total IgG and even McAb independent of antigens or PWM. Specific TCC required thyroid antigens to induce antibodies. The optimal McAg/TPO or Tg concentration was 10 ng/mL for total IgG production and 1 ng/mL McAg/TPO for McAb synthesis. The addition of PWM did not affect McAb production, but enhanced total IgG synthesis by B-cells under the influence of some specific TCC. Uncloned CD4+ cells induced both total IgG and McAb synthesis in the presence of PWM. With thyroid antigens, uncloned CD4+ cells induced total IgG synthesis at levels comparable to those of specific TCC, but induced smaller quantities of McAb in the presence of McAg/TPO. Our antigen-specific TCC could, therefore, stimulate specific B-cells to produce thyroid antibodies in vitro. Self MHC-II-reactive TCC could also induce specific antibodies by B-cells. Both self MHC-II-reactive CD4+ cells and antigen-specific CD4 cells may play an important role in the pathogenesis and/or perpetuation of autoimmune thyroid disease.

Characterization of site-specific polyclonal antibodies to c-erbA peptides recognizing human thyroid hormone receptors alpha 1, alpha 2, and beta and native 3,5,3'-triiodothyronine receptor, and study of tissue distribution of the antigen.

The translated products of v-erbA-related cDNAs have been demonstrated to be thyroid hormone receptors, and three different forms of receptor (alpha 1, alpha 2, and beta) have been found in human tissues. We synthesized five peptides corresponding to different portions of these three receptors and raised site-specific polyclonal-antipeptide sera in rabbits. Each antibody displayed high titer and specificity for its respective antigen when tested in an enzyme-linked immunosorbent assay. Each immunoprecipitated the corresponding in vitro translated products of human c-erbA alpha 1, alpha 2, or beta. Two of the antisera were specific for beta, one for alpha 2, and one detected a sequence common to alpha 1 and alpha 2. The fifth was directed toward the DNA-binding area of the proteins and interacted with each receptor. The four antibodies against alpha 1 and beta immunoprecipitated the native thyroid hormone receptor from rat liver and caused a partial shift in the elution profile of the native receptor labeled with [125I]T3 on Sephacryl S-300 column chromatography. The antibody against alpha 2 protein did not interact with native thyroid hormone receptor from rat liver. Using the indirect immunofluorescence technique with the five antibodies, we detected immunoreactivity primarily in the nucleus of cells in several tissues. In general, there was coordinate expression of both alpha and beta receptors in each organ examined, in agreement with previous data on tissue distribution of mRNAs for human thyroid hormone receptors. These studies prove the identity of v-erbA-related gene products with native thyroid hormone receptors and the expression of both alpha and beta receptors in nuclei of human and rat tissues.

Expression of HLA ABC and DR antigens in thyroid neoplasia and correlation with mononuclear leukocyte infiltration.

The rejection of tumor cells by the immune system depends on the production of tumor-associated antigens and the expression of HLA antigens on these cells. We therefore studied the expression of HLA ABC and DR antigens in malignant and benign thyroid disorders and correlated it with the types and extent of mononuclear cell infiltration. In the normal thyroid, HLA ABC expression was weak and focal, while it was diffusely present in benign disorders and in most but not all malignancies. HLA DR antigens, while absent or infrequently expressed in normal thyroid, were strongly but often focally expressed in all cases of autoimmune thyroid disease (AITD), as well as in most cases of malignant tumors and benign epithelium surrounding these tumors, and colloid nodule disease. There was a T cell predominance in all disorders, and the CD4+/CD8+ ratio was greater than 1 in most benign and malignant specimens. There was a direct correlation between the high expression of HLA antigens and dense inflammatory infiltration in AITD but not in most tumor specimens. Lack of such correlation suggests that the expression of HLA antigens is an autonomous event in tumors, independent of cellular infiltrate.

Microsomal antigen-reactive lymphocyte lines and clones derived from thyroid tissue of patients with Graves' disease.

Thyroid mononuclear cells (TMC) were maintained in long term cocultures with thyroid fibroblasts and thyroid epithelial cells from patients with Graves' disease, using medium supplemented with thyroid microsomal antigen (McAg) and IL-2. The TMC consisted predominantly of T4+ (CD4+, helper) and, to a lesser extent, T8+ (CD8+, cytotoxic/suppressor) lymphocytes, with a small number of macrophages and natural killer cells. The average T4+ to T8+ ratio was 3.2. From these cultures we obtained thyroid T cell lines and clones reactive to thyroid antigens. T Cell lines were tested in a microproliferation assay using thyroglobulin (Tg), McAg, tetanus toxoid, and IL-2. Of 14 lines from 6 patients, 2 proliferated in response to McAg when TMC plus thyroid fibroblasts were used as antigen-presenting cells. Clones of thyroid lymphocytes were obtained by culturing cells at limiting dilution with IL-2, McAg, and different types of autologous accessory cells. Peripheral blood mononuclear cells plus skin fibroblasts provided the best source of accessory cells, allowing near 100% cloning efficiency. Of 26 clones tested, 6 recognized McAg, 2 were Tg reactive, and 3 were autoreactive. All phenotyped clones were of the T4+ phenotype. Our method results in production of thyroid T cell lines and clones. The fibroblasts probably provided growth factors and/or collaborated with peripheral blood mononuclear cells as antigen-presenting cells. These lines and clones from patients with Graves' disease were predominantly helper T cells, in contrast to the previously demonstrated cytotoxic/suppressor cell predominance in cells from patients with Hashimoto's thyroiditis. This difference in cell function may help explain the differing clinical courses of these two closely related autoimmune thyroid diseases. The availability of long term microsomal antigen-specific T cell clones should allow careful analysis of the role these cells play in thyroid autoimmunity.