The thyroid cytotoxic autoantibody

Deborah Doniach: Discovering Thyroid Autoimmunity: The End of Horror Autotoxicus

Deborah Doniach MD, FRCP was born in Geneva, Switzerland in 1912. She attended high school at the Lycée Molière and medical school at the Sorbonne in Paris. Deborah married Israel (Sonny) Doniach in 1933. After the births of their two children, she resumed her studies at the Royal Free Hospital Medical School in London, graduating in 1945. After additional training in Immunopathology and Endocrinology, Dr. Doniach joined the faculty in the Department of Immunology at the Middlesex Hospital and rose to become Honorary Consultant Immunopathologist and full Professor of Clinical Immunology. During her career, Deborah enjoyed a long and fruitful collaboration with the chemist and immunologist Ivan Roitt. From their partnership sprang the seminal discovery that Hashimoto's thyroiditis is an autoimmune disease in which circulating antibodies target thyroglobulin, a normal thyroid protein. In addition, they demonstrated a separate antibody cytotoxic to thyrocytes, later found to target thyroid peroxidase. These novel insights ran counter to the prevailing scientific dogma contending that antibodies target only nonself antigens. Thus, the field of research into thyroid autoimmunity, and indeed into autoimmune diseases in general, was born. This work spawned a cadre of future investigators whose studies define our current understanding of thyroid autoimmunity and the broader spectrum of autoimmune disease. In her private life, Deborah was a free thinker who defied conventional norms of the day. She was vivacious, warm, and genuinely interested in everybody and everything. Deborah Doniach died on New Year's Day, 2004 at the age of 91.

Birth and coming of age of islet autoantibodies

This review takes the reader through 45 years of islet autoantibody research, from the discovery of islet‐cell antibodies in 1974 to today’s population‐based screening for presymptomatic early‐stage type 1 diabetes. The review emphasizes the current practical value of, and factors to be considered in, the measurement of islet autoantibodies.

Frequency and Distribution of DNA fragmentation in Hashimoto's thyroiditis and development of papillary thyroid carcinoma

Downregulation of apoptosis and high expression of bcl-2 play an important role in the development of follicular lymphoma. However, little is known about apoptosis in thyroid disease, particularly with respect to the development of papillary carcinoma from Hashimoto's thyroiditis. To study the early stages of cell death in various types of thyroid disease, surgical specimens from 31 patients including Hashimoto's thyroiditis (HT,n=7), papillary carcinoma (PC,n=12), Hashimoto's thyroiditis with papillary carcinoma (HTPC,n=5), and Graves' disease (GD,n=7) were examined by anin situ nucleotidyl transferase assay (ISNTA), which detects DNA fragmentation. Control normal thyroid tissue (NT,n=7) was obtained from surgically resected papillary thyroid carcinomas sampled away from the primary tumor. An immunohistochemical (IHC) method was used to detect bcl-2 expression. Positive ISNTA nuclei in thyroid follicular cells or tumor cells per section were counted in all parenchymal areas, excluding areas of lymphocyte aggregates. The intensity of bcl-2 staining was graded on a scale of 1+ to 3+. The number of ISNTA-positive thyroid follicular cells was a significantly higher in HT compared to GD. In addition, there was significantly lower number of ISNTA positive non-neoplastic thyroid follicular cells in HTPC compared to HT alone. Strong expression of bcl-2 was found in all cases of GD and NT, but much less bcl-2 staining was seen in HT. There was moderate expression of bcl-2 in HTPC and PC. These findings suggest that (1) DNA fragmentation of the thyroid follicular cells plays an important role in the thyroid injury in HT but not in GD, (2) expression of bcl-2 may overcome the apoptosis in GD but not in HT, and (3) downregulation of DNA fragmentation of the follicular cells in Hashimoto's thyroiditis associated with papillary carcinoma may suggest an important mechanism for tumor pathogenesis.

In vitro studies of ulcerative colitis. I. Reactions of patients' serum with human fetal colon cells in tissue cultures

By means of immunofluorescent methods it has been shown that sera from children with ulcerative colitis contain antibodies which react with fetal colon cells in tissue culture. 5 out of 13 sera from patients reacted positively when tested for staining antibodies while 12 sera from healthy individuals yielded negative results. The specificity of the staining reactions was confirmed by inhibition experiments. The staining capacity of various sera was correlated to their hemagglutinating titer when tested against phenol-water extracts of human colon. The presence of blood group substances of the ABO system on fetal colon cells in tissue culture could be demonstrated by application of fluorescent H agglutinins from eel. Cross-inhibition experiments indicated that the H agglutinins stained colon antigens which were different from those reacting with the antibodies of ulcerative colitis sera. The reactivity of cultured fetal colon cells with the antibodies in ulcerative colitis sera was retained for up to 12 days, with optimal staining at 4 to 5 days. Reactivity with H agglutinins was present for a longer period, sometimes more than 20 days. Although antigen could be shown to be present on fetal colon cells in tissue culture, exposure of the culture, in the presence of fresh guinea pig serum, to sera from patients with ulcerative colitis did not lead to any visible cytotoxic damage. In order to investigate the possible cytotoxic effect of the sera with a more sensitive technique, freshly explanted fetal colon was dispersed by trypsinization and the cells labeled with ³²P-orthophosphate. Subsequently, these cells were exposed to sera, in a final concentration of 30 per cent, from patients or healthy controls in the presence of fresh guinea pig serum (final concentration 15 per cent). Approximately 20 per cent of the cellular isotope was released into the medium within 150 minutes of incubation, but the release was the same in the samples treated either with patients' sera or normal control sera. Thus, under the present conditions, the patients' sera did not exert any specific cytotoxic action on colon cells.

Recombinant thyroid peroxidase-specific Fab converted to immunoglobulin G (IgG) molecules: evidence for thyroid cell damage by IgG1, but not IgG4, autoantibodies

A recombinant autoantibody Fab (SP1.4) to thyroid peroxidase (TPO), cloned from intrathyroidal B cell immunoglobulin genes, interacts with an epitope on TPO recognized by all patients with autoimmune thyroid disease. To compare the biological properties of IgG1 and IgG4 TPO autoantibodies, we converted Fab SP1.4 to full-length immunoglobulins. The SP1.4 heavy and kappa light chain variable region genes, spliced by overlap PCR to a mammalian signal peptide, were transferred to expression vectors for human IgG1, IgG4, and kappa L chains. Plasmids containing the IgG1 (or IgG4) heavy chain and the kappa L chain were cotransfected into SP2/0 mouse myeloma cells. Cells secreting TPO autoantibodies were cloned, and IgG1-SP and IgG4-SP were affinity purified from medium using protein G. Their subclass specificities were confirmed by enzyme-linked immunosorbent assay and fluorometry after binding to Chinese hamster ovary cells expressing cell surface TPO. Further confirmation of SP1.4 Fab conversion to full-length molecules was the ability of protein A to precipitate IgG1-SP and IgG4-SP complexed to [125I]TPO. IgG1-SP1.4, IgG4-SP1.4, and Fab SP1.4 had similar high affinities for TPO (Kd = approximately 2 x 10(-10) mol/L). Complexes of [125I]TPO and IgG1-SP (but not IgG4-SP) bound to peripheral blood mononuclear cells (PBMC), but not to a B cell line. Flow cytometry demonstrated Fc receptors Fc gamma RI, Fc gamma RII, and Fc gamma RIII on PBMC, but only Fc gamma RII on the B cell line. Together, these data indicate that IgG1-SP/TPO complexes bind to either Fc gamma RI on monocytes or RIII on natural killer cells. In assays for antibody-dependent cytotoxicity using PBMC, 51Cr release was higher for thyroid cells preincubated with IgG1-SP (13.4%) than with IgG4-SP (2.5%) or with culture medium alone (-0.7%). No specific 51Cr release was observed when either fibroblasts or Chinese hamster ovary cells expressing cell surface TPO were used as target cells. In conclusion, a human TPO-specific Fab converted to IgG1, but not IgG-4, can mediate cytotoxic effects on human thyroid cells in vitro. These observations support the clinical relevance of TPO autoantibody subclass distribution and emphasize the likelihood that, as opposed to being simple markers of thyroid damage, TPO autoantibodies may play a role in the induction of thyroid dysfunction in vivo.

Autoantigens in thyroid diseases

The autoantigens involved in autoimmune thyroid disease have now been extensively characterised, and the autoantibodies they evoke provide important aids to diagnosis, leading to early treatment of thyroid autoimmunity. The next stage in the puzzle is to determine towards which epitopes on the autoantigens the immune response is directed. We have already come a long way in the identification of immunodominant epitopes and have been able to identify one T cell epitope which has pathogenic capabilities. Identification of other T cell and B cell epitopes will help us understand the cell-mediated and humoral responses in greater detail and in time lead to more specific therapeutic intervention. A greater understanding of the mechanisms underlying one particular autoimmune disease will give us insights into other diseases, due to the belief that there may well be common underlying defects that, due to a multitude of factors, manifest as different diseases. The susceptibility factors in autoimmune thyroidits and autoimmune disease in general are very complex. A greater understanding is required of HLA associations and how particular peptides are presented in vivo. Are susceptible MHC types the ones capable of presenting the pathogenic peptides? Our major T cell thyroiditogenic epitope contains a T4 residue which accounts for over half the molecular weight of the peptide. Its structure is large and consists of a double benzene ring structure with four iodine atoms. It will be interesting to see how such a peptide can be presented and which residues bind T cell receptor or MHC. In summary we can say that autoimmune disease is due to a cocktail of factors which all contrive to tip the delicate balance of the immune system into an autoimmune state. HLA association may play a role in conferring an enhanced ability to select from a restricted repertoire of pathogenic epitopes, those epitopes perhaps only becoming available for presentation after interaction with environmental agents, whatever they may be. Following this, the normal regulation of self presentation and tolerance mechanisms break down and autoimmunity supervenes.

Assessment of antibody dependent cell cytotoxicity in autoimmune thyroid disease using porcine thyroid cells

Antibody Dependent Cell Cytotoxicity (ADCC) appears to be involved in Autoimmune Thyroid Disease (AITD). Homologous system may trigger non-specific reactions which might obscure specific ADCC. Heterologous target cells may be useful for studying ADCC, provided relevant antigen(s) are expressed. We therefore tested the capacity of porcine thyroid cells to elicit ADCC reaction in the presence of sera from various patients with AITD. Porcine thyroid cells were used in a 4-hr chromium release assay in the presence of 1/10 heat inactivated human sera and human peripheral blood lymphocytes at a 30:1 effector-target ratio. There was a significant correlation (r = 0.64; P < 0.01) between ADCC activities tested on human or porcine thyroid cells. Serum or IgG effects on porcine thyroid ADCC were dose-dependent between 1/10 to 1/10,000 dilutions. Non-thyroid cell systems were unaffected by thyroid cytotoxic sera. Porcine thyrocyte susceptibility to ADCC peaked at the fourth day of culture and was enhanced by addition of TSH or TSH and methimazole in the culture medium. Using this heterologous system, we demonstrated ADCC activity in a significant proportion of patients with thyroiditis (14/19), Graves' opthalmopathy (19/44) or of mothers of children with congenital hypothyroidism (14/39) and in the children themselves (15/39). Discrepancies observed in some sera between ADCC activity and antithyroperoxidase antibody suggest that thyroperoxidase is not the only antigen involved in ADCC. These results indicate that porcine thyroid cells appear suitable for ADCC assay in patients with AITD. Also this system should be helpful to characterize the antigen-antibody involved.

The microsomal/peroxidase antigen: modulation of its expression in thyroid cells

Evidence has accumulated in the last few years that the expression of the microsomal/peroxidase antigen (M/TPO-Ag) in thyroid cells is induced by TSH, through pathways which involve intracellular cAMP accumulation and protein synthesis. These data have been found true in any thyroid system studied so far, both in terms of immunologic and enzymatic activity of TPO. TSH and cAMP also increase the levels of the specific mRNA for TPO in thyroid cells from different species. Whether this phenomenon is due to a direct transcriptional regulation of the TPO gene, as shown in dog thyroid cells, or to posttranscriptional effects, as it would appear in FRTL-5 cells, remains to be clarified by future experiments. Thyroid stimulating antibody (TSAb) of Graves' disease also stimulates the expression of M/TPO-Ag. This finding gives further support to the relevance of TSAb in the pathogenesis of hyperthyroidism and explains the well known observation that the "microsomal" antigen is particularly abundant in glands of Graves' patients. The modulation of M/TPO-Ag surface expression by TSH can explain the decrease of circulating anti-MAb observed during L-thyroxine therapy in hypothyroid patients with Hashimoto's thyroiditis. Other agents, such as methimazole and sodium iodide, which influence thyroid cell function, do not directly interfere with the expression of M/TPO-Ag. Cytokines, such as gamma-interferon, interleukin-1, and interleukin-6 have been shown to inhibit the TSH-induced increase of TPO mRNA, but further investigations are required to elucidate the exact role of cytokines in the regulation of M/TPO-Ag expression.

Thyroid peroxidase and the induction of autoimmune thyroid disease

Animal models of autoimmune thyroid disease are associated with thyroglobulin (Tg) as autoantigen whereas in man the autoimmune response to microsomal antigen/thyroid peroxidase (TPO) appears to play a major role in thyroiditis. Consequently, we have compared the ability of TPO and Tg to induce thyroid autoantibodies and thyroid damage in mice known to be susceptible (CBA/J) or resistant (BALB/c) to thyroiditis induced using murine Tg. Groups of three to five mice were immunized twice using Freund's complete adjuvant with 80-100 micrograms highly purified porcine (p) TPO, pTg, rat (r) Tg, human Tg, bovine serum albumin (BSA) or BSA + 0.2 micrograms pTg (the level of Tg contamination of TPO). Four weeks after immunization with TPO, plasma from CBA/J (but not BALB/c) mice contained IgG class antibodies which bound to TPO-coated tubes in the presence or absence of excess Tg (and could therefore be clearly distinguished from Tg antibodies) but there was no evidence of thyroiditis in either strain of mice. In contrast, in CBA/J mice immunized with rTg and, to a lesser extent in mice that had received pTg, thyroid tissue was infiltrated with lymphoid cells and/or neutrophils and antibodies to pTg (but not pTPO) were present. Our observations demonstrate that induction of TPO antibody alone is insufficient to lead to thyroiditis in CBA/J mice. Further, these studies emphasize the complex interactions between MHC and different thyroid antigens in the processes leading to thyroid destruction.

Mapping of autoantigenic epitopes on recombinant thyroid peroxidase fragments using the polymerase chain reaction

Cloned cDNA templates of thyroid peroxidase (TPO) have been used in conjunction with the polymerase chain reaction (PCR) to express selected segments of the thyroid microsomal/peroxidase antigen (TMA/TPO) as recombinant protein in E. coli. Six small, different recombinant fragments averaging 120 amino acid residues and one large fragment (269 amino acids) of TPO which together encompass 80% of the extracellular region of the molecule have been produced and autoantibody (aAb) binding sites analysed by immunoblotting. A minimum of six independent, sequential antigenic determinants have been localized on the recombinant proteins and these map to the amino terminal, the central core region and the carboxyl terminal of the TPO molecule. More accurately, the six antigenic sites reside on overlapping recombinant TPO preparations termed R1a + R1b (residues 1 to 160) R1c (residues 145 to 250), R2b (residues 457 to 589), R3a (residues 577-677), R3b (residues 657-767) and R3c (residues 737-845). The large fragment of TPO termed R3 (residues 577-845) encompassing R3a, R3b and R3c also reacts with the aAbs. Different sera from patients with autoimmune thyroid disease contain antibodies to TMA/TPO which differ in their fine specificity. The use of recombinant molecular biological techniques together with PCR to prepare small segments of a large autoantigen as recombinant protein will now allow studies to progress on autoepitope mapping of the precise amino acid sequences of the TPO molecule with the use of synthetic peptides.

Cytotoxic assay of circulating thyroid peroxidase antibodies

This study describes an assay for the detection of cytotoxicity for thyroid cells in serum of patients with autoimmune thyroiditis. Quantitative measurement may be performed by DNA or [3H] leucine incorporation determinations. The cytotoxic effect is localized in the gamma-globulin fraction, and is complement-mediated. It is thyroid specific i.e. it is not observed with fibroblasts and patients with other autoimmune diseases (patients with lupus erythematosis or glomerulonephritis) do not have cytotoxic antibodies directed against thyroid cells. The thyroid cytotoxicity is related to the presence of antimicrosomal antibodies and the effect of circulating antibodies is inhibited by human thyroid peroxidase. These results strengthen the possible implication of circulating antithyroid peroxidase antibodies in thyroid damage observed in autoimmune thyroiditis.

Failure to detect complement-mediated antibody-dependent cytotoxicity against human orbital tissue cells in the serum of patients with thyroid-associated ophthalmopathy

Antibodies which are cytotoxic to human eye muscle cells and orbital fibroblasts in antibody dependent cell-mediated cytotoxicity (ADCC) are routinely detected in the serum of patients with thyroid-associated ophthalmopathy (TAO). In the present study sera from patients with TAO, most of which were shown to be positive in ADCC against eye muscle cell targets, were tested for complement-mediated antibody-dependent cytotoxicity (CMAC) against human and pig eye muscle cells, human (abdominal) skeletal muscle cells and human orbital fibroblasts, in 51Cr release assays. Several different assay protocols and complement sources were used and patient and age, sex matched normal sera compared. In preliminary studies tests were always negative when eye muscle cells, other skeletal muscle cells, or orbital fibroblasts were used as targets, regardless of the complement source, or concentration, or assay conditions used. When larger numbers of patients and normals were tested in a single assay mean (+/- SE) % specific lysis for patients with TAO was not significantly different from that for normals for either eye muscle cells or other skeletal muscle cells and taking the upper limit of normal as mean + 2 SD for the normals, tests were positive in no patient with either target. On the other hand ADCC tests were positive in 57% of the same sera tested with the same eye muscle cell targets. When human thyroid cells were used as targets, tests were positive in 10 of the 14 patients tested and monoclonal antibodies, in enzyme-linked immunosorbent assay, reactive with eye muscle antigens gave positive lysis of eye muscle cells.2+ t

Induction of microsomal antigen and comparison with histologic localization of HLA-DR in Graves' thyroid tissue

We have characterized thyroid microsomal antigen (M-Ag) prepared from Graves' and normal thyroid tissues using 100,000 x g thyroid membrane fractions in enzyme-linked immunosorbent assays with pooled polyclonal human sera containing high titers of antibody to M-Ag. A ten-fold parallel increase in dose inhibition potencies occurred with M-Ag preparations from Graves' as compared to normal thyroid tissue. The M-Ag preparations were further evaluated by SDS-polyacrylamide gel electrophoresis and proteins visualized by Western blot using high titer microsomal antibody (M-Ab) sera (n = 2) devoid of thyroglobulin antibody activity. We found discrete 100 kD relative molecular mass bands in Graves' M-Ag preparations (n = 3) under nonreducing conditions which were only poorly resolved in normal thyroid M-Ag (n = 3) using up to 100 micrograms of protein per lane. The cellular localization of M-Ag was then investigated using the avidin-biotin-peroxidase technique on frozen sections of Graves' and normal human thyroid tissue with a murine monoclonal antibody reactive with human M-Ag and thyroid peroxidase. M-Ag reactivity was similar in both Graves' and normal thyroid tissues and localized to the entire follicular cell membrane with more intense staining occurring on the inner follicular cell membrane. This was in contrast to follicular cell staining for HLA-DR antigen which was present in 6 of 10 Graves' tissues examined and absent in normal thyroid tissue. Staining for HLA-DR antigen also occurred on the follicular cell surface membrane with occasional enhancement at the thyrocyte apical cell membrane. We conclude: a) M-Ag is induced approximately 10-fold in Graves' thyroid tissue and can be objectively quantified in ELISA systems, 2) There were no detectable qualitative differences between M-Ag from Graves' and normal thyroid tissue, and 3) HLA-DR antigen was detected on 60% Graves' tissues in a cell surface distribution similar to that observed for M-Ag in both Graves' and normal tissues.

Biological activity of lymphocytotoxic antibodies in Graves' disease and Hashimoto's thyroiditis

Sera of 48 patients with Graves' disease (GD) and 23 with Hashimoto's thyroiditis (HT) were tested for lymphocytotoxic (LCT), granulocytotoxic (GCT) and monocytotoxic (MCT) activity. In GD, 12 patients (25%) had cold-reacting LCT and 13 patients (27%) had warm-reacting LCT. LCT were cytotoxic to both B and T cells but the majority of sera with cold-reacting LCT and eluates from lymphocytes were more cytotoxic to B lymphocytes. Warm-reacting LCT were directed exclusively against B cells. LCT did not correlate with peripheral lymphocyte counts, antithyroglobulin or antimicrosomal antibodies, sex, age, pregnancies, thyroid status or medication. However the mean duration of the disease was 15 months in LCT positive group and 55 months in LCT negative group (p less than 0.01). Weak GCT were found in 8 of 35 sera (23%). Six of 33 sera (18%) contained cold-reacting MCT and 9 (27%) had warm-reacting MCT. Some cytotoxins were directed against several types of cells as evidenced by cytotoxicity of eluates from lymphocytes against PMN and/or monocytes. Of 23 patients with HT, 11 (48%) had cold-reacting LCT. None had warm-reacting LCT. Sera and eluates from lymphocytes showed predominant cytotoxicity toward B cells. No correlation to the presence of antibodies, sex, age, pregnancies, thyroid status or medication was detected. Four of 23 sera had weak cold-reacting GCT, 5 had cold-reacting MCT which killed on average 31% of monocytes and 4 had weak warm-reacting MCT. Twelve of 22 sera from GD and HT had cytotoxic activity against thyroid cells (TCT). TCT correlated with LCT at p less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

The thyroid "microsomal" antibody revisited. Its paradoxical binding in vivo to the apical surface of the follicular epithelium

We have shown that thyroid monolayers derived from the glands of patients with autoimmune thyroid disease have immunoglobulin (Ig) bound to their surface. This appears to have been deposited in vivo rather than during preparation of the monolayers, a view supported by our finding of such deposits on the apical margin of follicular cells in sections cut from these glands and stained with conjugated anti-immunoglobulin. It is likely that these deposits represent specific binding of so-called "microsomal" autoantibodies to the surface of the thyroid cells in vivo since staining of partially disrupted follicles ("half-melons") with Hashimoto serum containing microsomal autoantibodies in the indirect immunofluorescence (IFL) test, localized the antigen on the apical surface of the cells lining the follicular cavity. Thus, paradoxically, although the antigen is relatively inaccessible, autoantibodies do reach and combine with the thyroid surface in vivo and may therefore play a role in pathogenesis.

Natural cytotoxicity of peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis against human adult and fetal thyroid cells

Natural cytotoxicity of human peripheral blood leukocytes against fetal and adult human thyroid cells was investigated in vitro. Natural killer (NK) cell activity was determined at various effector: target cell ratios in a standard 51Cr release assay with human thyroid cells as targets. The effector cells were unfractionated peripheral blood mononuclear cells obtained by Hypaque-Ficoll gradient centrifugation. We have demonstrated that peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis exhibit natural cytotoxicity against both human fetal and adult thyroid cells. This was effector: target cell ratio and incubation time dependent. Although there was a tendency for increased killing of fetal thyroid cells by peripheral blood leukocytes from patients with Hashimoto's thyroiditis compared to age/sex matched normal subjects this was not significant and there were no significant differences between the two groups for killing of adult thyroid cells. A possible role for natural cytotoxicity in progressive thyroid tissue destruction in Hashimoto's thyroiditis is discussed.

Reexpression of blood group ABH antigens on the surface of human thyroid cells in culture

Using indirect immunofluorescence (IFL) on viable human thyroid cultures, it has been shown that, although adult follicular cells do not express blood group ABH antigens in vivo, they invariably reexpress the corresponding antigens on the cell surface when cultured in monolayers, even for very short periods. The absence of blood group antigens on noncultured thyroid cells was confirmed by negative IFL on cell suspensions obtained after enzymatic digestion of the glands, whereas these antigens were readily demonstrable on cell suspensions obtained by trypsinization of established monolayers. The quantitative expression of ABH antigens on individual thyroid cells was variable and the cell-surface IFL pattern due to binding of blood group isoantibodies was different from that given by organ-specific thyroid autoantibodies on viable cultures. Reexpression of blood group antigens by cultured thyroid cells could not be related to the secretor status of the donors, the presence of a particular source of serum in the culture medium or cell division in vitro. After 2-3 wk in culture, thyroid cells became morphologically dedifferentiated and no longer displayed blood group antigens, though they still expressed cell-surface beta 2-microglobulin. Fibroblasts present in the primary thyroid cultures were invariably negative for ABH antigens. These results demonstrate that the surface antigenic repertoire of cultured human cells is not necessarily identical to that present on the same cells in vivo. Furthermore, the possibility that blood group natural isoantibodies bind to the cell surface must be taken into account in experiments in which cultured thyroid cells are exposed to human sera.

Studies on thyroid cell surface antigens using cultured human thyroid cells

Human thyroid cells in primary culture were used for studies of thyroid cell surface antibodies in patients with thyroid autoimmune disorders. Radioiodinated IgG preparations containing thyroid microsomal antibody (TMAb), thyroid stimulating antibody (TSAb) and/or thyroglobulin antibody (TgAb) were tested for binding to thyroid cells. Binding was observed with radioiodinated IgG from patients with Graves' disease, Hashimoto's thyroiditis and idiopathic myxoedema containing TMAb, irrespective of the presence of TSAb and TgAb, while negative results were obtained with normal IgG. A dose-dependent inhibition of binding to thyroid cells was produced by the addition of the corresponding unlabelled IgG preparations. Evidence for tissue specificity was provided by the absence of binding to human skin fibroblasts used as controls. Preabsorption with human thyroid microsomes completely abolished the binding to thyroid cells of a radioiodinated TMAb positive IgG preparation, while only incomplete removal of the reactivity to thyroid microsomes was produced by preabsorption with thyroid cells. These data suggest that some but not all microsomal antigenic determinants are expressed on the thyroid cell surface. Binding to thyroid cells was also observed with purified TgAb, indicating that thyroglobulin antigenic determinants are present on the surface of thyroid cells. No evidence of binding was obtained with a TSAb positive Graves' IgG preparation with undetectable TMAb and TgAb. Unlabelled IgG preparations containing TMAb from patients with either Hashimoto's thyroiditis or idiopathic myxoedema were shown to inhibit the binding to thyroid cells of radioiodinated TMAb positive Graves' IgG and vice versa. These data indicate that antibodies present in these thyroid autoimmune disorders share common thyroid cell surface antigens. However, the binding of radioiodinated IgG from a patient with idiopathic myxoedema was only partially inhibited by Graves' or Hashimoto's IgG, suggesting that some of the thyroid cell surface antibodies of idiopathic myxoedema may not be detectable in other thyroid autoimmune disorders.

A microcytotoxicity assay for thyroid-specific cytotoxic antibody, antibody-dependent cell-mediated cytotoxicity and direct lymphocyte cytotoxicity using human thyroid cells

A microcytotoxicity assay for detection of thyroid-specific complement-dependent cytotoxic antibody (cytotoxic antibody), antibody-dependent cell-mediated cytotoxicity (ADCC) and direct lymphocyte cytotoxicity was developed using human, thyroid epithelial cells as targets. Thyroid tissue was obtained from patient with Graves' disease and was treated with collagenase and then trypsin. The red blood cells, interfollicular fibroblasts and infiltrating lymphoid cells in thyroid tissue from patients with Graves' disease could be removed by this procedure. To obtain entirely single cells as target cells, the suspension of dispersed thyroid epithelial cells was allowed to stand for 1 h at 4 degree C in culture medium to allow cell clumps to settle. For assay of cytotoxic antibody, a mixture of the single target cells, patient's serum and human complement was incubated in microwells for 18 h. After removing the detached cells, remaining target cells in the wells were fixed, stained and counted to assess cytotoxicity. For assay of ADCC and of direct lymphocyte cytotoxicity, target thyroid cells were precultured in the microwells for 18 h. Then effector cells with or without patient's serum were added and cultured further for 24-72 h. Cytotoxicity was assessed as described above. Adherence of effector cells to target thyroid cells sometimes disturbed the enumeration of target cells when the effector/target cell ratio was high. With this microassay system 3 different cytotoxic immune reactions against human thyroid cells could be measured quantitatively at the same time on 2-3 ml blood samples.

Presence of the organ-specific 'microsomal' autoantigen on the surface of human thyroid cells in culture: its involvement in complement-mediated cytotoxicity

The presence of organ-specific cell surface-reactive antibodies in sera of patients with autoimmune thyroid diseases (ATD) has been detected by indirect immunofluorescence on viable blood group O normal thyroid cultures. The cell surface determinants involved in this reaction have been identified as the thyroid 'microsomal' antigen which is thus also represented on the outer surface of the plasma membrane. The reactivity persists when F(ab')2 fragments from positive sera are used. Non-thyroid cells present in the monolayers, as well as human adrenal or fibroblast cultures, do not show positive staining. Human thyroid cells progressively lose both cell surface and intracytoplasmic antigenic components during the first week of culture. The exposure and reactivity of this antigen on the cell surface do not depend upon unmasking effects of proteolytic enzymes used for dispersal of the cells. The 'microsomal' antigen on the cell surface is also involved in the complement-mediated cytotoxic effect of sera from ATD patients on freshly dispersed thyroid cells. Thyroglobulin antibodies failed to stain viable thyroid monolayers, even when these were previously incubated with purified human thyroglobulin, indicating that this protein or possible receptors for it cannot be detected on the cell surface under these conditions. Similarly, some thyrotoxicosis sera containing thyroid-stimulating but not microsomal antibodies, gave negative reactions on viable cultures.

Measurement of circulating thyroid microsomal antibodies by the tanned red cell haemagglutination technique: its usefulness in the diagnosis of autoimmune thyroid diseases

Thyroid-microsomal antibodies were quantitated by a new technique utilizing tanned sheep red blood cells coated with human thyroid microsomal antigens. This haemagglutination assay (MCHA) correlated with the immunofluorescent antibody (FAB) but not with the thyroglobulin haemagglutination antibodies (TGHA) assay. Of forty-one patients with Hasmimoto's thyroiditis, thirty-nine (95%) were MCHA but only twenty-four (59%) TGHA positive. Titres were similar for the hypothyroid and euthyroid patients. Patients less than 20 years of age had either negative (50%) or low titre (less than 1:160) TGHA but 100% positive MCHA at titres greater than 1:1280. Of twenty-one patients with Graves' disease eighteen (86%) were MCHA and six (29%) TGHA positive. Of thirty-two patients without thyroid disease eleven (34%) were MCHA and/or TGHA positive. On the basis of family history and associated abnormalities, in eight of eleven, positive antibodies may have been due to subclinical Hashimoto's thyroiditis. Fourteen subjects of a control group (10%) were MCHA positive. Seven of ten examined had goitres. MCHA is a simple and quantitative test, useful in the diagnosis of autoimmune thyroid diseases.

Parietal cell antibodies. Part II. Cytotoxic activities of parietal cell antibodies. Experiment 1. The observations on cytotoxic activities of parietal cell antibodies to normal human parietal cells in vitro. Experiment 2. The histochemical changes of rat stomach after administrations of rabbit anti-rat gastric mucosa sera

Cytotoxic activities of P.C.A. to normal parietal cells were demonstrated in vitro. The changes were very similar to those of thyroid cells provoked by Hashimoto serum. The cytotoxic component was found to be immunoglobulin G. Complement was not added. Rabbit anti-rat gastric mucosa sera had no effects on the gastric secretion in rats, but histochemical changes were demonstrated. The changes were transient and returned to the normal state 60 minutes after injection of Anti-RGM sera. Activities of succinic dehydrogenase were most affected, particularly 3 minutes after injection. Decrease of activities gradually recovered to the normal condition. The comparison of C.A.G. with C.Th. was made. By the comparison between C.A.G. and C.Th., and by the results of experiments, the author considers that C.A.G. has the immunologically identical aspects with C.Th.. The author also considers that some immunological mechanisma are playing a role in the pathogenesis of C.A.G.

Relationship of age-specific incidence rates to immunological aspects of Hashimoto's thyroiditis

Studies of the age-specific incidence rates of the appearance of Hashimoto's thyroiditis indicate that this disorder appears at random in a genetically preselected population. Following an initial lag in the first few years of life, the disease appears at a constant rate thereafter in this population.The age-specific incidence rates were similar to those previously reported for Graves' disease. Moreover, there is considerable evidence implicating cell-mediated immunity in both diseases, with the likelihood of cooperating humoral antibodies as well. It may be hypothesized that the two diseases are primarily due to genetic defects in immunological surveillance, which result in an inability to destroy or control a specific forbidden clone of thymicderived lymphocytes which may arise by normal random mutation. The T-lymphocyte interacts with its complementary antigen (on a hitherto normal thyroid cell), setting up a cell-mediated immune response; in addition it may cooperate with bursa-equivalent lymphocytes, which then produce humoral antibodies. It is possible that both cell-mediated immunity and humoral antibodies are necessary for the full expression of the disease.

Studies on thyroid immunity. VII. Splenectomy and monkey immune thyroiditis: thyroidal function and thyroxine transport

The role of the spleen in humoral antibody formation and in the pathogenesis of immune thyroiditis was studied by splenectomizing four monkeys (Macaca mulatta) prior to thyroid isoimmunization. Splenectomized animals, as well as intact controls, were subjected to sequential immunizations and the course of the immune disease was followed by periodic thyroid biopsies and frequent humoral antibody measurements over a period exceeding 1 yr. Extirpation of the secondary lymphoid organ markedly inhibited agglutinating antibody response, prevented formation of complement-fixing antibodies, but had no effect on thyrocytotoxic antibodies. In animals subjected to immunization in complete adjuvant a trend towards a decrease in serum complement levels was evident at the terminal stages of the experiments. Despite the inhibitory effects on some immunological parameters, splenectomy in monkeys prior to thyroid isoimmunization did not interfere with the initiation and progression of pathological processes in the thyroid. Indeed in all splenectomized animals immunized with thyroid plus complete adjuvant, fibrotic thyroid lesions (4+) with virtual obliteration of thyroid follicles were evident, in some as early as 120 days after primary immunization; in contrast, non-fibrotic and less severe lesions were noted in the intact animal despite being repeatedly subjected to similar immunization procedures over a period of 340 days. Immunization in the absence of complete adjuvant did not induce thyroid lesions in the presence or absence of spleen. In all animals with severe thyroid lesions, thyroid function decreased as revealed by T₄ and ¹³¹I-T₃ resin uptake measurements. Paper electrophoresis of serum specimens from a monkey subjected to thyroid isoimmunization in complete adjuvant (and after equilibration with ¹²⁵I-T₄) showed a pronounced retention of ¹²⁵I-T₄ radioactivity at the gamma globulin region indicating formation of antibodies to thyroxine. On the other hand, in sera with a low thyroid antibody titre as in splenectomized monkeys or in those animals immunized within complete adjuvant, T₄-binding antibodies were not evident. It is concluded that removal of the spleen prior to thyroid isoimmunization in monkeys, rather than inhibiting the severity of the disease may even aid and abet immunopathogenic events destructive to the thyroid.

Persistence of thyroid microsomal and thyroglobulin antigens in primary cultures of human thyroid epithelium

The changes in the amount and distribution of thyroglobulin and thyroid `microsomal' antigens were studied in primary explant and monolayer cultures of human thyroid epithelium which were alive for about 60 days. Both explant and monolayer cultures produced thyroglobulin in vitro at all times during the 60-day period of observation. However, the number of cells containing the thyroid `microsomal' antigen and the amount of antigen in individual cells both diminished though the antigen was detectable in a proportion of viable cells in all cultures at all times during the 60-day period of observation of this report.

Studies of the pathogenetic role of humoral antibodies reacting with subcellular organ antigens. II. Passive immunization of rats with anti-rat rabbit immune sera

Immunizing injections of rat liver and kidney mitochondrial fractions were administered to rabbits, and the effects of injecting the antisera into rats were investigated. Rats receiving antiserum to rat liver mitochondria showed impaired clearance of sulphobromphthalein, and developed hepatic fibrosis which in one animal progressed to cirrhosis. There was no increase in albuminuria and the kidneys showed no histological differences from those of control rats receiving normal rabbit serum. Renal changes were virtually confined to rats receiving antiserum to rat kidney mitochondria: these animals excreted increased amounts of protein and showed increased cellularity of the glomeruli, tubular casts and hydropic changes in the tubular epithelium. The significance of these findings is discussed.

A clinical and immunological study of adrenocortical insufficiency (Addison's disease)

Fifty-one patients with adrenocortical insufficiency were subdivided into three groups according to the nature of their adrenal disease; twelve patients with idiopathic, twenty-three patients with probable idiopathic and sixteen patients with tuberculous adrenal insufficiency. The importance of objective confirmation of a clinical diagnosis of adrenal insufficiency is stressed and the difficulties of classification of many patients with adult onset adrenal insufficiency are discussed. Idiopathic and probable idiopathic adrenal insufficiency had a sex ratio that was predominantly female (2·5:1) with a mean age of onset of 33 years.

Antibodies to adrenal cortex were detected by the methods of immunofluorescence and complement fixation. They were detected in the serum of 80% (20:25) of the females with idiopathic or probable idiopathic adrenal insufficiency and in only 10% (1:10) of the males. The titre of the adrenal antibody was low (≤32) as tested either by immunofluorescence or complement fixation. The serum of only one patient with tuberculous adrenal insufficiency reacted with adrenal tissue in the complement fixation test but the immunofluorescence method showed that this serum reacted with the vascular endothelium and not the secretory cells. No correlation was observed between the duration of the clinical illness and the presence, or absence, or titre of the adrenal antibody. Adrenal antibody was not detected in the sera of fifty-one control subjects matched for age and sex. Four of sixty-nine patients with lymphadenoid goitre, one out of ninety-three patients with diabetes mellitus and none of 230 patients with thyrotoxicosis, primary hypothyroidism or pernicious anaemia had antibody in the serum specific for adrenocortical secretory cells.

There is a clinical and immunological overlap between idiopathic adrenal insufficiency and other diseases associated with autoimmune phenomena— thyroid disease, atrophic gastritis and hypoparathyroidism.

It is concluded that idiopathic adrenal insufficiency belongs to a group of diseases that are characterized clinically by onset predominantly in females, by aggregation in the same group of patients, by familial tendency, by the presence of organ-specific antibodies in the serum and histologically by lymphocytic infiltration and atrophy. While only one tissue of the group may be predominantly affected, the other tissues are frequently the site of subclinical disease. There is no set order in which the different tissues are affected. Serological evidence of adrenalitis is rare in patients with thyroid disease or pernicious anaemia, but thyroiditis and gastritis are common in patients with adrenalitis.

Two autopsies on patients with idiopathic adrenal insufficiency are described. One case had the classical features of adrenal atrophy with gross reduction in size of the glands, islets of secretory epithelial cells and a moderate degree of lymphocytic infiltration. In the other case, the adrenal glands were only slightly less than normal in size, there were few adrenal epithelial cells and a dense lymphocytic infiltration and some fibrosis. The histology resembled that of the thyroid in Hashimoto goitre.

If the term `autoimmune' adrenalitis is to be substituted for idiopathic adrenal insufficiency, it should be on the understanding that while autoimmune mechanisms may be of primary importance in the pathogenesis of adrenal disease this has yet to be proven.

Serum lactic dehydrogenase isoenzymes in "myxoedema heart disease"

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Experimental thyroiditis in the rhesus monkey. I. Cytotoxic, mixed-agglutinating and complement-fixing antibodies

Rhesus monkeys inoculated repeatedly with a crude extract of pooled rhesus thyroids plus complete Freund adjuvant produced autoantibodies cytotoxic for monkey and human thyroid cells in vitro. No cytotoxicity was observed with normal rhesus kidney or adrenal cells taken as controls from the same animals. The specific cytotoxic reaction was absorbed by thyroid microsomes, but not by other tissue fractions. Monkey (as well as human) thyroiditis sera failed to fix complement with thyroglobulin although both fixed complement with crude thyroid suspensions. The cytotoxic antibody was heat stable (56°C for 30 min) and required complement for damage to tissue cells. Fractionation by sucrose gradient ultracentrifugation demonstrated that the cytotoxic antibody had a sedimentation rate of about 7S and was stable to sulphydryl agents, whereas the complement-fixing antibody sedimented more rapidly and was largely inactivated by mercaptoethanol treatment. Thus in this case, cytotoxic antibody is not identical with the over-all complement-fixing activity of an antiserum. The presence of organ specific antigen on the surface of cultured rhesus thyroid cells was detected by the mixed agglutination antiglobulin reaction using monkey antisera. The curves of antibody production detected by mixed agglutination and cytotoxicity tend to correspond although the former test was 10–100 times more sensitive.

Auto-immune reactions in ulcerative colitis

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