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R Volpé

Publications and source records attributed to R Volpé.

At least 19 recordsLinked to original sources
PubMed1992

A perspective on human autoimmune thyroid disease: is there an abnormality of the target cell which predisposes to the disorder?

It has been suggested recently that autoimmunity could be regarded as a physiological response of the normal immune system to autoantigens caught up in an inflammatory response to viral or bacterial antigen expressed in the target tissue. Other theories to explain autoimmunity include molecular mimicry whereby a viral or microbial hapten similar to an autoantigen initiates the production of autoantibodies that cross react with an autoantigen, with a subsequent immune response reacting with autologous cell structures which are homologous with the particular microorganism. There has also been a suggestion that there may be a genetic abnormality of the target cell which is necessary for the initiation of autoimmune thyroid disease. The present review examines these proposals and provides evidence against an antigen-driven origin for autoimmune thyroid disease (AITD). Currently, there is no valid evidence for viral involvement, and likewise the evidence for molecular mimicry as an initiating factor does not hold up to scrutiny. While a genetic abnormality of the thyrocyte may be important in certain animal models of AITD, in the human there is no evidence for such an abnormality. Evidence that AITD is derived from a disturbance of immunoregulatory mechanisms has been documented elsewhere and would appear to be the most appropriate explanation for these disorders. The immunoregulatory disturbance itself may be related to an abnormality of the mechanism of specific antigen (i.e. normal autoantigen) presentation to appropriately induce T lymphocytes and that theory will require further illumination.

Animals↗
PubMed1991

Interleukin 2-activated killer cells do not mediate autologous thyrocyte lysis in autoimmune thyroid disease in vitro.

Because of interest in IL-2, and IL-2-activated killer cell-induced hypothyroidism in humans, we attempted to study an in vitro system that might prove to illuminate this disorder. We have thus studied interleukin 2 (IL-2--0, 12.5, 25, or 50 U/mL) activated killer cell-mediated autologous thyrocyte lysis, as well as cytotoxic activity in IL-2-stimulated mononuclear cell supernatants in 7 patients with autoimmune thyroid disease (2 Graves' disease and 5 Hashimoto's thyroiditis) using the 51Cr release assay. Controls included 14 patients with nonautoimmune thyroid disease (3 nontoxic goiter, 8 follicular thyroid adenoma, 2 papillary thyroid carcinoma, and 1 medullary carcinoma of the thyroid). Soluble IL-2 receptor (sIL-2R) in supernatants of peripheral mononuclear cells stimulated by IL-2 from these patients also was measured. Whereas in the control preparations, IL-2-activated killer cell activity was increased in a dose-dependent fashion relative to the IL-2 concentration, as well as to the effector cell/target cell ratio, in preparations from patients with autoimmune thyroid disease, this activity was not elevated as the IL-2 concentration was increased. The susceptibility of thyrocytes to the lytic effect of IL-2-activated killer cells was higher in controls than that in autoimmune thyroid disease (at concentrations of IL-2 of 0, 12.5, 25, and 50 U/mL) (p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Studies of CD4+ (helper/inducer) T lymphocytes in autoimmune thyroid disease: demonstration of specific induction in response to thyroid peroxidase (TPO) in vitro and its relationship with thyroid status in vivo.

We have studied by flow cytometric analysis the antigen specific activation of CD4+ (helper/inducer) T lymphocytes by purified human thyroid peroxidase (TPO). Peripheral blood mononuclear cells were obtained from 26 patients with Graves' disease (GD), 16 with Hashimoto's thyroiditis (HT), 7 with nontoxic nodular goiter (NG), and 14 normal subjects (N). Cells were cultured for 7 days in the presence or absence of TPO at final concentrations of 3, 30, and 300 ng/mL. When harvested, cells were reacted with an FITC-conjugated anti-CD4 and a PE-conjugated anti-HLA-DR murine monoclonal antibodies. The percentage of HLA-DR+ CD4+ cells (activated CD4+ cells) was determined by a flow cytometer. In the absence of TPO, CD4+ cells had been activated without any specific stimulant. This is known as the autologous mixed lymphocyte reaction (AMLR). In the AMLR, CD4+ cells from GD and HT were less activated compared to those from NG and N. Results of TPO-specific activation were expressed as an incremental increase of activated CD4+ cells (II) (percentage of activated CD4+ cells cultured with TPO minus percentage of activated CD4+ cells cultured without TPO). II of N, GD, HT, and NG were 0.37 +/- 0.21, 2.20 +/- 0.45,** 2.0 +/- 0.66,* and 0.35 +/- 0.27 (mean +/- SEM), respectively (**p less than 0.01; *p less than 0.05 vs N). When patients were further subdivided, the highest mean II was found in patients with hyperthyroid GD (p less than 0.01), followed by euthyroid HT (p less than 0.05) and euthyroid GD (p less than 0.05), however there was no significant difference between hypothyroid HT and N. In conclusion (1) AMLR reactivity of CD4+ cells from GD and HT was impaired, (2) however, CD4+ cells from both GD and HT were significantly more induced by TPO compared to N, and (3) this induction depends, in part, on the in vivo thyroid status.

Adolescent↗
PubMed1991

Concordant Graves' disease after bone marrow transplantation: implications for pathogenesis.

The current working hypothesis on the pathogenesis of autoimmune disease focuses on the interactions between susceptibility genes and environmental stimuli. In Graves' disease it is postulated that aberrant expression of HLA class II antigens on thyroid epithelial cells permits the presentation of specific thyroid antigen to activated lymphocytes. Evidence suggests that thyrocyte HLA-DR expression is secondary to the production of cytokines by presensitized T-lymphocytes. A 20-yr-old woman and her 18-yr-old brother presented with classical findings of Graves' disease with ophthalmopathy within a year of each other. Diagnosis was confirmed by demonstration of elevated serum levels of T4 and T3, strongly positive titers of TSH binding inhibitory immunoglobulins, and histological examination after subtotal thyroidectomy. Eight years previously, acute life-threatening aplastic anemia in the brother led to therapeutic transplantation of bone marrow from his sister. After the procedure, 100% of his peripheral leucocytes were genotype 46,XX. HLA typing performed before transplantation and 2 months after thyroidectomy in the female indicated complete identity with her brother's leukocytes for class I and class II antigens. Thyroid autoantibodies at this time were weakly positive. Although the concordance of thyroid disease in these patients could be due to chance, the patients were of different sexes, the family history was negative, and neither the probands nor the first degree relatives bore the HLA-DR3/B8 antigens. We propose that the male passively acquired a clone of programmed or activated lymphocytes from his sister and that his hyperthyroidism was not primarily dependent on exposure to specific thyroid-derived antigen.

Adolescent↗
PubMed1991

Effects of recombinant human interleukin-2 and tumor necrosis factor-alpha with or without interferon-gamma on human thyroid tissues from patients with Graves' disease and from normal subjects xenografted into nude mice.

We have compared the effects of interleukin-2 (IL-2) or tumor necrosis factor-alpha (TNF alpha) administration with or without interferon-gamma (IFN gamma) on Graves' and normal thyroid tissue xenografts in the nude mouse (in the absence of an intact immune system) in terms of possible functional, immunological, or histological changes. The dosages of recombinant human IL-2, TNF alpha, and IFN gamma given to each mouse were 250, 800, and 4000 U, respectively; they were injected ip daily for 6 consecutive weeks. The parameters measured included the free T4 index, thyroid autoantibodies, and mouse TSH during the course of the study. Thyroid epithelial cell (TEC) HLA-DR expression was measured in thyroid tissue before xenotransplantation and at death; in addition, light microscopic studies were carried out at those times. There were no significant differences in thyroid function between the results in unstimulated (control) animals and those obtained with cytokine administration in either group of tissues, with the exception of the group receiving TNF alpha together with IFN gamma; in this latter group, the free T4 index declined significantly 4-6 weeks after commencement of treatment in the animals with normal thyroid tissue xenografts. The reduction of thyroid function induced by the combination of IFN gamma and TNF alpha observed in normal thyroid tissue may be due to inhibition of thyroperoxidase and thyroglobulin gene transcription. However, there was no such effect on the Graves' thyroid tissue xenografts, perhaps because of down-regulation of this tissue in response to cytokines, after having been released from long term in vivo immune stimulation. On the other hand, TNF alpha plus IFN gamma induced TEC HLA-DR expression on both types of thyroid xenografts at death, although IL-2 alone did not induce HLA-DR expression, and IFN gamma induced TEC significantly only on normal thyroid xenografts (but not on Graves' xenografts). In light microscopic examination, Graves' thyroid xenografts treated with IL-2 alone or TNF alpha plus IFN gamma appeared normal at death. In addition, normal thyroid xenografts treated with the same cytokines did not show discernible differences compared to those at human surgery or when the xenografts were untreated at death. We conclude that Graves' TEC did not differ from normal TEC in any significant fashion at the time of death, aside from a reduced responsiveness to the stimuli applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The effect of xenotransplantation of human thyroid tissue following radioactive iodine-induced thyroid ablation on thyroid function in the nude mouse.

We have attempted to determine whether xenotransplanted human thyroid tissue into nude mice would act as a physiological substitute for the mouse thyroid gland after the mice had been rendered hypothyroid, using radioactive iodine (131I). The dosage of 0.2 millicuries of 131I was given to each mouse. The xenotransplantations of human thyroid tissue, i.e., normal, Graves' and nontoxic multinodular goitre, were carried out three weeks after radioactive ablation. The values of TSH in all mice rose to high levels (71 +/- 15.6 ng/ml, +/- SD) by three weeks after 131I administration. The TSH values in the mice declined rapidly and reached normal levels by 3-5 weeks after xenotransplantation. In addition, the serum T4 values were generally in the euthyroid range by 3-6 weeks after xenotransplantation. There were no marked differences in the changes of serum T4 and TSH when the three groups were compared. These results indicated that the xenografted human thyroid tissue permitted a return to a normal feedback system as reflected by normal serum TSH and T4 values in the animals. The Graves' thyroid tissue reverted to normal physiological function when removed from its human (abnormal) immune environment, signifying that Graves' thyrocytes are mere passive captives to immune events. This model should prove to be useful in the study of human thyroid physiology and pathophysiology.

Animals↗
PubMed1991

Autoimmunity causing thyroid dysfunction.

Considerable evidence for a genetically induced antigen-specific defect in suppressor T lymphocytes as the basis for AITD has been derived from several laboratories and via different types of experimental techniques. This defect may result from abnormal antigen presentation to T lymphocytes via an aberrant antigen-specific HLA-related gene. In addition, there is now evidence for additive effects on reducing generalized suppressor T lymphocyte numbers and function by environmental factors as well as hyperthyroidism itself. These effects would be superimposed on the organ-specific defect. Such effects on generalized suppressor T lymphocyte numbers may act as precipitating and self-perpetuating factors. Presentation of the antigen by the thyroid cell via HLA-DR expression on its cell membrane does occur as a result of IFN-gamma production by T lymphocytes. This appears to be secondary to the initial specific immune assault and is not a primary inductive step. Although it may be important as an amplifying intermediate factor, antigen presentation cannot perpetuate the process in the absence of the underlying immune disorder. There is, indeed, no evidence for an underlying antigenic abnormality or stimulus in human autoimmune thyroid disease, and the initiating event would appear to be due to perturbation of the generalized immune system superimposed on the organ-specific immunoregulatory abnormality. Variations in the serologic and clinical expression of AITD would appear to depend on the severity of the original organ-specific disturbance in suppressor T lymphocyte function, plus the added factor of environmental influences playing on generalized suppressor T lymphocyte function and numbers. Remissions in Graves' disease brought about by antithyroid drugs may well be via their effect on modulating thyroid cell activity; this then reduces thyrocyte-immunocyte signaling, allowing remission to occur in those patients with a partial organ-specific defect in suppressor T lymphocytes.

Antibodies, Anti-Idiotypic↗
PubMed1990

CD4 cells from patients with autoimmune thyroid disease secrete interferon gamma after stimulation by thyroid microsomal antigen; CD8 cells suppress this secretion.

The production of interferon gamma (IFN gamma) by peripheral blood mononuclear cells (PBMC) from normal persons and patients with autoimmune thyroid disease (AITD) has been studied in vitro either spontaneously or after stimulation with thyroid microsomal antigen (TMc) or liver microsomal antigen (LMc). The numbers of IFN gamma secreting cells were measured by a spot-ELISA technique. AITD PBMC spontaneously contained significantly more IFN gamma secreting cells than did normal control PBMC. Moreover, TMc antigen caused a significantly greater number of IFN gamma secreting cells in AITD PBMC than did LMc antigen, whereas there was no significant difference between the two antigens in the normal control PBMC preparations. Thus TMc antigen caused a stimulation of the number of IFN gamma secreting cells only in the AITD PBMC and not in the normal PBMC. CD4 plus B cells or CD4 cells alone (with monocytes in both instances) contained more IFN gamma secreting cells under unstimulated conditions than did CD8 cells in both groups. AITD CD4 plus B cells (or CD4 cells) contained more IFN gamma secreting cells than did normal cells, but there was no significant difference between both groups in terms of the number of CD8 IFN gamma secreting cells. Normal CD4 plus B cells (or CD4 cells) responded to TMc antigen significantly more than did total normal PBMC at 10 and 1,000 ng/ml TMc. This was not the case when patients' CD4 plus B cells (or CD4 cells) were compared with patients' total PBMC, in which there were no significant differences. This suggests that CD8 suppressor activity was inadequate in AITD and thus the deletion of CD8 cells did not result in an increase in IFN gamma secreting cells. When TMc antigen was added to AITD CD8 cells, there was a significant diminution of IFN gamma secreting cell numbers at 10 and 1,000 ng/ml TMc. Moreover, adding autologous CD8 cells to CD4 plus B cells resulted in a significant suppression of IFN gamma production at 100 and 1,000 ng/ml TMc in both groups. AITD CD8 cells appeared to be somewhat less effective than normal CD8 cells, but this did not reach significance. It is thus concluded that AITD CD4 cells respond specifically to TMc antigen. CD4 production of IFN gamma appears to be suppressed by CD8 cells activated with antigen and the CD8 cells appear to be involved in the regulation of IFN gamma production by the CD4 cells.

Adult↗
PubMed1990

Effects of recombinant human interferon gamma on human thyroid tissues from patients with Graves' disease and normal subjects transplanted into nude mice.

We have attempted to determine whether interferon gamma (IFN gamma) would enhance, sustain or induce autoimmune thyroid disease (AITD) in xenotransplanted thyroid tissue from patients with Graves' disease or normal persons (actually paranodular tissue) in nude athymic mice, in the absence of an intact immune system. A dosage of 4000 U/mouse of human IFN gamma (hIFN gamma) was injected intraperitoneally daily for six consecutive weeks into the xenotransplanted mice. The parameters measured included the free T4 index, thyroid autoantibodies and TSH during the course of hIFN gamma injections. Thyroid epithelial cell (TEC) HLA-DR expression was measured in the thyroid tissue before xenotransplantation and at sacrifice; in addition, light and electron microscopic studies were carried out at those times. There were no significant differences in thyroid function between the control results and those obtained with hIFN gamma in either group of tissues. TEC HLA-DR expression was significantly increased by hIFN gamma in the normal group, but insignificantly in the Graves' group. In both light and electron microscopic observations, Graves' tissue (whether or not treated with hIFN gamma) was indistinguishable at sacrifice from normal thyroid tissue. The appearance had markedly altered from the same Graves' tissue examined at the time of the initial human surgery, which then showed the usual histological appearance of this disorder. We conclude that IFN gamma induced HLA-DR expression alone is not sufficient to sustain the ongoing process of AITD in this model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Hashimoto's thyroiditis manifesting monoclonal lymphocytic infiltration.

Hashimoto's thyroiditis (HT) and lymphoma are sometimes difficult to distinguish between. Moreover, lymphoma sometimes develops in a thyroid gland from pre-existing HT. Open- or large-needle biopsy usually distinguishes between them; the specimen may be examined histologically and subjected to immunohistochemistry. Another possible method of examination is fine-needle aspiration biopsy (FNAB). The cells obtained may be evaluated cytologically, and subjected to flow cytometry, using various antibodies. In this study, anti-kappa and anti-lambda antibodies are especially important, as a gross predominance of kappa or lambda B lymphocytes infiltrating the thyroid is evidence for a B cell monoclone. In this study, 15 patients were selected because of their rapidly growing goitres. They all underwent FNAB. Five had cytology typical of HT, and no evidence of monoclonality on flow cytometry. They were diagnosed as HT without further histopathology. The remaining 10 patients had cytology suspected of lymphoma, or evidence of monoclonality on flow cytometry, or both. These patients underwent open- or large-needle biopsy. Only three of them were diagnosed histopathologically as lymphoma; the other seven were diagnosed histopathologically as HT, making 12 cases of HT in all. Five of these 12 cases, and one of the three cases of lymphoma showed flow cytometrical evidence of monoclonality; thus evidence of monoclonality from FNAB, while interesting, does not necessarily serve to differentiate between HT and lymphoma. Furthermore, the immunohistochemical assessment of monoclonality did not correlate with the flow cytometrical assessment. Follow-up evidence will be required to discover whether those patients with a B cell monoclone in their HT are the ones who develop a lymphoma.

Aged↗
PubMed1990

In vitro production of interferon-gamma by peripheral blood from patients with Graves' disease, Hashimoto's thyroiditis and rheumatoid arthritis.

The production of interferon-gamma (IFN-gamma) by peripheral blood mononuclear cells (PBMC), CD4 cells, or CD8 cells in response to interleukin-2 (IL-2) stimulation has been studied; the samples were obtained from 12 healthy control subjects, 19 patients with Graves' disease (10 hyperthyroid and nine euthyroid), 13 patients with Hashimoto's thyroiditis (four hypothyroid and nine euthyroid), and 15 patients with rheumatoid arthritis (11 active and four inactive). A dose of IL-2 (25 U/ml) was utilized to induce IFN-gamma by PBMC from all four groups. The incremental increase in IFN-gamma values (with IL-2 stimulation minus without stimulation) was significantly less in PBMC from patients with Graves' disease, Hashimoto's thyroiditis, and rheumatoid arthritis than that in PBMC from control subjects. The values from PBMC in patients with Graves' disease in a euthyroid state were below normal but greater than those from patients with Graves' disease in a hyperthyroid state. The incremental increase in IFN-gamma values from Graves' disease PBMC correlated with the serum TSH values (r = 0.622, P less than 0.01), but not with thyroid autoantibodies (anti-thyroid microsomal antibodies, anti-thyroid microsomal antibodies, nor TSH-binding inhibitory immunoglobulin activities). The incremental increase in IFN-gamma from PBMC from both control subjects and Graves' disease was correlated with that from CD4 cells (r = 0.711, P less than 0.01), but not with that from CD8 cells. The production of IFN-gamma in response to IL-2 from PBMC in Graves' disease correlated inversely with thyroid function, appearing to reflect the very effect of hyperthyroidism in this process. The precise explanation of these phenomena remains unclear. The decreased response of IFN-gamma to IL-2 stimulation by PBMC from patients with Graves' disease, Hashimoto's thyroiditis, and rheumatoid arthritis seems to be a non-specific phenomenon occurring in both organ specific autoimmune disease and systemic autoimmune disease. It may be due to a down-regulation in autoimmune disease of CD4 cells in response to IL-2, a decreased level of IL-2 cellular receptors or a decreased receptor affinity, associated increased soluble IL-2 receptors, or a defect of the intra-CD4 cellular IL-2 signal to produce or release IFN-gamma in the conditions studied.

Adult↗
PubMed1990

Effects of supernatants of peripheral blood mononuclear cells stimulated by thyroid microsomal antigen on thyrocyte HLA-dr expression in vitro.

Supernatants of 5 day cultures of peripheral blood mononuclear cells (PBMC) stimulated by thyroid microsomal antigens (TMA), and liver microsomal antigens (LMA) have been utilized to induce HLA-DR expression on human thyroid epithelial cells (TEC). The PBMC were obtained from 8 normal control persons and 13 patients with autoimmune thyroid disease (AITD) (7 Graves' disease and 6 Hashimoto's thyroiditis). The TEC HLA-DR expression was measured by an enzyme-linked immunosorbent assay (ELISA) technique. TEC HLA-DR expression was calculated as follows: (experimental optical density-control optical density) x 10(3): TEC HLA-DR index: % HLA-DR expression of IFN gamma 100 U/ml stimulation; and stimulation index (SI): TEC HLA-DR expression index induced by PBMC supernatants with antigen stimulation/TEC HLA-DR expression index induced by PBMC supernatants without antigen stimulation x 100. Supernatants without antigen stimulation from both normal control subjects and patients were able to induce TEC HLA-DR expression only minimally: 36.7 +/- 32.6 (mean +/- SD) TEC HLA-DR index for normal controls and 21.3 +/- 15.5 TEC HLA-DR index for AITD (not significant). The SI curves of both TMA and LMA were significantly different between control and AITD using two-way ANOVA test (p less than 0.01). TMA-stimulated PBMC supernatants from the patients increased TEC HLA-DR expression when compared to basal level using paired t-test; TMA 1 ng/ml, SI 179 +/- 99, less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Peripheral blood T lymphocyte sensitization to thyroid microsomal antigen from patients with Graves' disease negative for circulating anti-thyroid microsomal antibodies.

We have studied thyrocyte HLA-DR expression induced by supernatants of peripheral blood mononuclear cells (PBMC) stimulated by thyroid microsomal antigen (TMA), as an index of sensitization of the T lymphocyte in autoimmune thyroid diseases; we have studied PBMC from 11 normal control persons and 19 patients with Graves' disease (GD) in whom serum anti-thyroid microsomal antibodies (AMA) were either not detectable (9 patients) or were positive (10 patients). Thyrocyte HLA-DR induction in response to TMA-treated PBMC supernatants from GD was significantly different from that of normal controls (p less than 0.05, ANOVA). TMA-stimulated GD PBMC supernatants increased thyrocyte HLA-DR index [TMA 1 ng/ml, SI 143 +/- 82 (mean +/- SD), p less than 0.05], but normal PBMC supernatants did not. However there was no significant difference in response in terms of the thyrocyte HLA-DR expression induced by TMA-stimulated PBMC supernatants between AMA seronegative vs seropositive GD. These results suggest the possibility of some dissociation of the activities of T lymphocytes and B lymphocytes in patients with GD in response to thyroid microsomal antigen with or without anti-thyroid microsomal antibodies.

Adult↗
PubMed1990

Serum interferon gamma levels in autoimmune thyroid disease.

The lymphokine, interferon gamma (IFN gamma) is considered to play an important role in the development of autoimmune thyroid disease (AITD); the main source of IFN gamma has been shown to be CD4 cells when stimulated by soluble antigen. We have measured the serum IFN gamma concentration in 42 patients with AITD (24 Graves' disease and 18 Hashimoto's thyroiditis) and 9 normal control subjects, using a sandwich enzyme-linked immunosorbent assay (ELISA) (detectable limit, 1 IU/ml). One of normal controls, 14 of the 24 patients with Graves' disease, and 5 of the 18 patients with Hashimoto's thyroiditis had detectable IFN gamma levels. Patients with Graves' disease were found to have higher concentrations of serum IFN gamma (11.6 +/- 15.8 IU/ml, mean +/- SD) than normal controls (1.1 +/- 0.3 IU/ml). However, the values in patients with Hashimoto's thyroiditis (9.4 +/- 15.5 IU/ml) were not significant when compared to those in normal controls. Serum IFN gamma values in patients with AITD did not correlate with serum anti thyroid autoantibodies (antithyroglobulin, antithyroid microsomal antibody, or TSH binding inhibitory immunoglobulin activity) or with thyroid function. Thus, increased in vivo production of IFN gamma in Graves' disease as evidenced in these serum concentrations might reflect T cell activity, but does not appear to be an accurate reflection of intrathyroidal events.

Autoantibodies↗
PubMed1989

Nontoxic nodular goiter and papillary thyroid carcinoma are not associated with peripheral blood lymphocyte sensitization to thyroid cells.

We tested the claim that uni- and multinodular goiter (UNG and MNG) and papillary carcinoma (PC) of the thyroid are autoimmune thyroid diseases (AITD) similar to Graves' disease (GD) and Hashimoto's thyroiditis (HT). The expression of HLA-DR on cultured thyroid epithelial cells (thyrocytes) from UNG, MNG, and PC after coculture with autologous peripheral blood mononuclear cells (PBMC) was compared with that on GD and HT cells. The thyrocytes also were cultured with interferon-gamma (IFN gamma) alone. A cytotoxicity assay involving 51Cr-labeled thyrocytes, anti-HLA-DR, and complement was used to determine HLA-DR expression. Stimulation of thyrocytes with 200 U/mL IFN gamma induced HLA-DR (expressed as a cytotoxicity index) equally well on all thyrocytes [AITD (n = 6): IFN gamma, 23.8 +/- 7.7 (+/- SD); unstimulated, 3.6 +/- 2.0; UNG (n = 6), MNG (n = 9), and PC (n = 5): IFN gamma, 22.5 +/- 4.7; unstimulated, 4.0 +/- 3.0]. When cocultured with autologous PBMC, the values were: AITD, 24.9 +/- 10.1; UNG, MNG, and PC, 3.8 +/- 3.7 (P less than 0.001). The supernatants from the AITD cocultures had higher IFN gamma concentrations (by RIA) than those from the other cocultures. We conclude that in UNG, MNG, and PC, the peripheral blood helper T-lymphocytes are not sensitized to thyrocyte membrane antigen(s); consequently, little if any IFN gamma is produced in cocultures, and hence, there is no increase in thyrocyte HLA-DR expression, unlike the situation in AITD (GD and HT). Thus, UNG, MNG, and PC are not primarily autoimmune in nature, as defined by a lack of sensitization of the PBMC of such patients to thyroid antigen(s).

Antigens, Surface↗
PubMed1989

Lack of effect of methimazole on thyrocyte cell-surface antigen expression.

The nature of the immunosuppressive effect of antithyroid drugs has been a subject of controversy. It has been claimed that these agents exert a direct effect on the immune system, although we and others have suggested that the drugs affect the thyroid cells primarily with consequent reduced thyrocyte-immunocyte signalling. This may occur from reduced thyroid hormone production and/or reduced antigen presentation by the thyrocytes to local T lymphocytes. Using a cytotoxicity assay system, with chromium-51 labelling, monoclonal antibodies against thyroperoxidase (TPO) and HLA-DR, and complement, we have measured the expression of TPO and HLA-DR on cultured normal human thyroid cells; we have also measured thyroglobulin (Tg) release by radioimmunoassay into the medium of the cultured cells. The thyroid cells were stimulated with TSH or thyrotropin binding inhibitory immunoglobulin (TBII) for 48 hours before measuring for TPO induction, and with interferon gamma (IFN-gamma) (with or without TSH or TBII) for thyrocyte HLA-DR expression. A dosage of 1.6 milliunits per ml of TSH resulted in a significant increase in TPO expression on thyrocytes when compared with control unstimulated thyroid cells (p less than 0.001). The concentrations of Tg released into the medium with TSH or TBII were also significantly higher than those of the control thyrocytes. IFN-gamma at 200 units per ml induced HLA-DR expression, but did not induce thyrocyte TPO expression, or Tg release. Addition of the antithyroid drug, methimazole (MMI), at different concentrations, in addition to the other stimulators, IFN-gamma, TSH, or TBII, did not result in any inhibition of TPO, Tg release, or HLA-DR expression on the thyroid cells. It would thus appear that the pathways for stimulation for the expression of TPO and HLA-DR appear to be different. Finally, MMI does not cause its immunosuppressive effect by any reduction of thyroid antigen expression or release.

Antigens, Surface↗