Circulating T-cell subsets in Graves' disease: differences between patients with active disease and in remission after 131I-therapy

Elevated CD69 expression on naive peripheral blood T-cells in hyperthyroid Graves' disease and autoimmune thyroiditis: discordant effect of methimazole on HLA-DR and CD69

This study investigated T-cell activation markers HLA-DR and CD69 in both naive (CD45RA+) and memory (CD45RA-) CD4+ as well as CD8+ T cells in peripheral blood of patients with autoimmune thyroiditis (AT, N = 28) or hyperthyroid untreated Graves' disease (GDH, N = 34) using three-color flow cytometry. It was demonstrated that patients with AT, but not those with GDH, expressed increased amounts of HLA-DR antigen compared to healthy subjects (HS, N = 26) on total CD4+ (AT: 14.1%; GDH: 11.3%; HS: 10.9%) and CD8+ cells (AT: 31.9%; GDH: 23.5%; HS: 19.4%) as well as on CD45RA- CD4+ cells (AT: 11.2%; GDH: 7.7%; HS: 7.9%). In GDH (+71%) and AT (+91%) only the proportion of HLA-DR+ CD45RA+ CD8+ cells was increased vs HS. Furthermore, euthyroid GD patients on methimazole (GDE, N = 22) displayed greater HLA-DR+ expression on total and CD45RA- cells within both CD4+ (+37 and 40%, respectively) and CD8+ cells (+47 and 93%, respectively) than GDH. In addition, total and CD45RA+ CD4+ and CD8+ cells were increased vs HS. In contrast, proportions of CD69 positive T cells were increased in AT and GDH on total CD4+ (+97 and 74%, respectively) and CD8+ (+95 and 68%, respectively) cells and all subsets thereof (except for CD45RA- cells in GDH), but normalized upon thyrostatic treatment. We conclude that patients with autoimmune thyroid disease harbor an almost twofold greater proportion vs HS of (a) HLA-DR+ CD45RA+ CD8+ T cells, and of (b) CD69 on total CD4+ and CD8+ cells, and an even more marked elevation on their CD45RA+ subset in AT and untreated GD. In addition, (c) thyrostatic treatment by methimazole in GD is accompanied by a further increase in circulating HLA-DR+ CD4+ and CD8+ cells and their CD45RA- subsets, but decreased CD69 expression. These data suggest association of HLA-DR expression with ongoing autoimmunity, while increased CD69 expression relates in part also to elevated thyroid hormone concentration in GDH.

Activated naive CD4+ peripheral blood T cells in autoimmune thyroid disease

To better understand the clinical significance of changes in lymphocytes in thyroid disease this study analyzed the proportion of CD19+, CD3+, CD4+ and CD8+ cells among circulating lymphocytes in Graves' disease (GD, n = 34) and autoimmune hypothyroidism (AH, n = 28) vs healthy subjects (n = 15). In addition, the expression of CD25 and CD45 isoforms on CD4+ T cells as well as their modulation by methimazole in patients with GD was measured using three color flow cytometry. It was observed that, irrespective of age, both patients with GD (17.6 +/- 7.0% +/- SD) and those with AH (19.0 +/- 9.5%) had an increased percentage of the CD25+CD45RA+ (naive) subpopulation of helper cells vs healthy subjects (7.9 +/- 2.3%, p < 0.0001). In patients with AH peripheral memory cells and hence overall CD25+ cells were more frequent among helper cells (56.7 +/- 12.2%) than in healthy subjects (40.8 +/- 14.0%, p < 0.001). Patients with GD (46.2 +/- 13.4%) did not differ from normal subjects in this respect. Treatment of GD with MMI reduced the percentage of CD25+CD45RA+ cells among CD4+ cells toward values seen in healthy subjects. In addition, we confirm previous reports that CD8+ cells toward values seen in healthy subjects. In addition, we confirm previous reports that CD8+ cells are significantly reduced in AH (23.9 +/- 4.9%) and untreated Graves' disease (23.2 +/- 6.6%) vs healthy subjects (32.2 +/- 5.9%, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody binding profile of purified and cell-bound CD26. Designation of BT5/9 and TA5.9 to the CD26 cluster

The CD26 activation antigen (Ag) which is expressed on a subpopulation of human T cells has been characterized as dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5). In this paper, we describe the antibody binding profile of CD26/DPP IV, purified from human peripheral blood lymphocytes. The purified molecule binds to the anti-Ta1, anti-1F7 and anti-134-2C2 monoclonal antibodies (mAb), reported to react with cell-bound CD26 Ag. Among unclustered mAb recognizing T cell antigens, two, anti-BT5/9 and anti-TA5.9 were found to react with purified and cell-bound CD26 Ag. The classification of the BT5/9 Ag, the functional properties of the BT5/9+ T cell subset, as well as the in vivo effect of anti-BT5/9 mAb administration, are re-interpreted in the light of its specificity. Applying the anti-TA5.9 mAb in three color FACS analyses, we demonstrated that CD26+bright cells co-express CD45RO but not HLA-DR and CD38.

Intrathyroidal activated (Ia+) T-lymphocyte CD+ subsets and B cells in Graves' hyperthyroidism respond rapidly to propylthiouracil therapy: demonstration using fine needle aspirates and two-colour laser flow cytometry

Using a rapid (whole blood lysis) single laser microfluorocytometric technique that permitted the simultaneous analysis of two monoclonal antibody surface markers tagged with different fluorescent dyes, the intrathyroidal (IT) and peripheral blood (PB) activated [Ia+ = DR+] T-lymphocyte CD3+ subsets and [F(ab')2+] B cells were studied in hyperthyroid patients with Graves' disease (GD) before and after 1-4 months of propylthiouracil (PTU) therapy. IT lymphocytes were obtained by serial fine needle aspiration. In untreated patients a marked quantitative (approximately < 10 fold) increase in activated (Ia+ CD3+) T-lymphocytes as well as CD4+ and CD8+ subsets, for IT compared to PB sites, was found. The percentages of Ia+ CD4+ and Ia+ CD8+ within Ia+ CD3+ were not significantly different between the two sources of T cells. F(ab')2+. B cells were significantly increased (approximately 2-3 fold) in IT compared to PB. In hyperthyroid GD patients, PTU therapy induced rapid and specific changes within the Ia+ CD3+ subsets, namely a reduction in the Ia+ CD4+ subset and an increase in the Ia+ CD8+ subset, resulting in a marked decrease in the Ia+ CD4+/Ia+ CD8+ ratio. These changes occurred in association with a reduction in serum T4 and T3 concentration. No significant changes could be detected within the total (predominantly non-activated) CD3+, CD4+ or CD8+ lymphocyte subsets within PB and only a small decrease in the CD4+/CD8+ ratio was demonstrated in IT, following PTU treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum beta 2-microglobulin levels in thyroid diseases

Serum beta 2-microglobulin was measured in 38 patients with thyroid diseases. Serum levels of beta 2-microglobulin were significantly increased in patients with untreated Graves' disease (median: 200 nmol l-1; P less than 0.0002), and in patients with untreated toxic adenomas (222 nmol l-1; P less than 0.0005) compared to 60 healthy control subjects (147 nmol l-1). Following antithyroid treatment of euthyroidism, serum beta 2-microglobulin decreased significantly in both Graves' disease (162 nmol l-1) and toxic adenomas (175 nmol l-1); values which were not significantly different from that of the control group. The level of serum beta 2-microglobulin in 12 patients with hypothyroidism was not different from that of the control group. However, in untreated hypothyroidism serum beta 2-microglobulin was positively correlated with serum thyroxine (T4) (rho = 0.69; P less than 0.05) and free thyroxine index (FT4I) (rho = 0.72; P less than 0.02). It is concluded that elevated levels of serum beta 2-microglobulin may reflect the increased metabolism in patients with thyrotoxicosis. Increased levels in active Graves' disease may also partly be caused by immunological activation.

Functional study of T lymphocyte responsiveness in patients with dementia of the Alzheimer type

The autologous mixed lymphocyte reaction (AMLR) was used to study T lymphocytes in a group of patients with dementia of the Alzheimer type (DAT) in order to confirm the observation that their T cell proliferation in AMLR was greater than in age-matched controls, and to investigate other pathways of T cell activation, searching for correlations between immunologic and clinical findings in DAT. The mean proliferative response in AMLR was increased in patients with DAT. No differences between patients and age-matched controls were detected when other pathways of T cell activation were investigated. The degree of response in the AMLR varied among patients with DAT. This fits with the suggestion that the disorder may be a heterogeneous syndrome.

Graves' disease: phenotypic and functional analysis at the clonal level of the T-cell repertoire in peripheral blood and in thyroid

We have investigated at the clonal level the repertoire of intrathyroid and peripheral T lymphocytes in three patients with Graves' disease using a high efficiency cloning technique. Clonal efficiencies ranged from 10 to 31% for intrathyroid, and from 19 to 100% for peripheral T cells. In Graves' disease the phenotypic analysis showed similar percentages of CD3+ CD4+ CD8- and CD3+ CD4- CD8+ clones in thyroid infiltrates and peripheral blood. The functional evaluation showed similar or lower proportions of cytolytic clones in thyroid infiltrates with respect to peripheral blood. Furthermore, the proportions of intrathyroid and peripheral T-cell clones capable of releasing interleukin-2 and/or gamma-interferon in response to mitogen stimulation were similar. Finally, 44% of intrathyroid clones were neither cytolytic nor able to release IL-2 and gamma-interferon. These results are strikingly different from those obtained in Hashimoto's thyroiditis, where the large majority of intrathyroid T-cell clones are cytolytic and the proportions of clones able to release gamma-IFN are remarkably increased in thyroid infiltrates when compared to those obtained from peripheral blood. Taken together, these data suggest a different role for T lymphocytes in the pathogenesis of the two major human autoimmune thyroid diseases.

Autoimmune thyroid disease: immunological, pathological, and clinical aspects

Autoimmune thyroiditis, most notably Hashimoto's thyroiditis, appears to be increasing in prevalence and is now more easily detected by sensitive laboratory tests and more invasive procedures such as fine needle aspiration. During the last decade, marked progress has been made in the understanding of these diseases. There is a greater awareness of the interaction between the humoral and cell-mediated arms of the immune system in autoimmune thyroiditis. Recent studies implicate a subpopulation of suppressor T lymphocytes which have an antigen-specific defect, resulting in their suboptimal interaction with the helper T lymphocytes and subsequent autoimmune manifestations. There is some evidence that thyroid epithelial cells which inappropriately express HLA-DR may enhance presentation of thyroid antigens to the immune system, possibly significant in the initiation or enhancement of the autoimmune response. The presence of various antithyroid autoantibodies allows the use of laboratory assays to confirm the clinical diagnosis and predict the results of treatment. There appears to be predisposing genetic factors in the development of autoimmune thyroiditis, with some geographical and racial differences. Environmental factors, most notably dietary intake of iodine, have also been implicated in the pathogenesis of Hashimoto's thyroiditis. Several animal models have been developed addressing such issues. Ongoing studies in the areas of postpartum thyroiditis and childhood thyroiditis are helpful in clarifying their relationship with Hashimoto's thyroiditis. Graves' disease and postpartum thyroiditis are being investigated as possible causes of postpartum depression. The association of Hashimoto's thyroiditis and carcinoma of the thyroid gland is still controversial, but its relationship with malignant lymphoma is now well accepted. Thus, although the pathogenesis of autoimmune thyroiditis remains elusive, there has been significant refinement of the clinical diagnosis, and immunological abnormalities of specific intrathyroidal lymphocytes have been identified. Hopefully, these new areas of knowledge will assist in the treatment of these diseases and in the prevention of the development of malignant lymphomas of the thyroid gland.

Functional and biochemical characterization of a human T-cell antigen related to the T3-Ti activation pathway

In this report we studied the antigen identified by the 5/9 monoclonal antibody. This antigen is expressed on approximately 15% of resting T lymphocytes with helper activity and increases following T-cell activation both in vivo and in vitro. The 5/9 monoclonal antibody triggered T-cell proliferation in the presence of suboptimal doses of phorbol12-myrisate 13-acetate (PMA) but this effect was strongly inhibited by antibody-induced modulation of the CD3 T-cell-receptor complex. The observation that a number of T-cell lines were brightly stained by the 5/9 monoclonal antibody after being activated with phytohemagglutinin (PHA) and PMA allowed the molecular characterization of the 5/9 antigen as well as the analysis of the biochemical mechanisms occurring after cell stimulation with 5/9 monoclonal antibody (Mab). An activated Jurkat T-cell line was labeled with 125I on the membrane: the monoclonal antibody immunoprecipitated a molecule displaying an apparent molecular weight of 34 kDa. In addition, 5/9 molecules, purified by immunoprecipitation from Jurkat cells, were found associated to a Ca2+ phospholipid-dependent protein kinase activity.

Functional studies of T4+ lymphocyte subsets distinguished by the monoclonal antibody 5/9: suppressor-effector T4+ lymphocytes derive from the 5/9+ subset

Human T lymphocytes bearing the cell surface antigen T4 are functionally heterogeneous, exerting helper/inducer, suppressor-inducer, suppressor-effector, and cytotoxic activities. Other cell surface antigens with a more restricted expression may help separate T4+ lymphocytes into functionally distinct subsets. This report describes the regulatory functions of T4+ lymphocytes fractionated by the monoclonal antibody 5/9, which detects a cell surface antigen present on 50-60% of T4+ lymphocytes. The results indicate that both 5/9+ and 5/9- T4 subsets contain helper/inducer and suppressor-inducer cells. Suppressor-effector activity, however, is found predominantly within the 5/9+ T4 subset. The 5/9 antibody thus identifies the suppressor-effector subset of T4+ lymphocytes, although it does not distinguish between T4+ cells with or without helper/inducer and suppressor-inducer functions.

Induction of circulating activated suppressor-like T cells by methimazole therapy for Graves' disease

Thyrostatic drug treatment of Graves' disease suppresses excessive thyroid hormone synthesis and causes a parallel decrease in serum thyroid autoantibody levels. The mechanism of this immunosuppression is unknown. We studied methimazole-induced immunoregulatory effects prospectively in 14 patients with Graves' disease treated for up to six months. The numbers of circulating activated, HLA-DR-positive T helper/inducer cells decreased gradually, from 8.3+1.7 percent (+SD) to 1.0+1.7 percent (P less than 0.001). HLA-DR-positive T suppressor/cytotoxic cells increased transiently at one month, from 2.0+1.9 percent to 12.6+6.4 percent (P less than 0.001), and returned to 2.9+3.7 percent at six months. Methimazole did not alter the HLA-DR expression of T cells in vitro. In two patients, the helper activity of T cells in inducing autoantibody secretion in vitro was substantially reduced after one month of methimazole treatment. Before treatment, large proportions of thyroid-infiltrating T-cell subsets expressed the activation markers HLA-DR, interferon-gamma, and interleukin-2 receptors, which were partially lost during therapy. Methimazole treatment was accompanied by a gradual reduction in circulating levels of thyrotropin-receptor, microsomal, and thyroglobulin autoantibodies. These results are compatible with the view that methimazole-induced immunoregulation in Graves' disease is mediated by a direct inhibitory effect on thyrocytes. This inhibition is in turn accompanied by marked changes in the proportions of activated T helper-like and T suppressor-like cells. This altered T-cell activation profile reflects, at least in part, the functional suppression of autoantibody production observed in methimazole-treated patients with Graves' disease.

T cell subsets and thyroid-stimulating antibodies in patients with Graves' disease in clinical remission

Patients with active Graves' disease almost constantly show phenotypic alterations of T lymphocytes, such as an increase of "activated" cells recognized by various surface markers (e.g. la antigens). Such alterations are present in a certain number of apparently cured patients. The data herein reported refer to 25 patients with Graves' disease in clinical remission, in whom we have attempted to correlate T cell subset imbalances, the presence of thyroid-stimulating antibodies (TSAb) and the outcome of the subsequent relapse. The results obtained show a significant association between TSAb and the increase of la-positive T cells: no relationship was found between TSAb and other T lymphocyte subsets. One-year clinical follow-up of the patients enabled us to see relapses of hyperthyroidism in only two patients, who had shown in the first control both TSAb positivity and increased la-positive T cells. These results, in our opinion, suggest a role of la antigens expression on T lymphocytes in the clinical course of Graves' disease.

Evidence of T-lymphocyte functional impairment in Huntington's disease

Huntington's Disease (HD) is a degenerative neurological disorder with autosomal dominant transmission. Although immunological defect(s) have been postulated, no confirmed laboratory evidence for this exists. In the present study we observed activated T cells in the peripheral blood of HD patients (using 4F2 monoclonal antibody), whereas the percentage of T cells bearing T-cell activation markers such as HLA-DR and MLR4 antigens was normal. We then studied T cells of HD patients in some functional assays. Since it has been suggested that autologous mixed lymphocyte reaction (AMLR) includes several immune mechanisms in which distinct cell subsets interact and perform distinct regulatory functions, it is conceivable that the remarkable deficiency of AMLR herein observed in HD patients results from some abnormal immune regulation which may contribute to the pathology of this condition. Additional experiments demonstrated a defect of AMLR in three asymptomatic young sibs of HD patients, and coculture experiments between T cells of patients (as responders) and non-T cells of their sibs (as stimulators), and vice versa, produced no proliferative response. Subnormal responsiveness in allogeneic MLR was also observed. Normal or enhanced PHA-induced production of both IL-2 and IFN-gamma in vitro was detected. These experimental data suggest a cellular branch of the immune system in HD; however, they do not indicate if this defect is primary or secondary to the disease itself.

Autoimmune thyroid disease: purification and phenotypic analysis of intrathyroid T cells

A phenotypic analysis of T cells infiltrating the thyroid of patients with autoimmune thyroid disease (both Graves' disease and Hashimoto's thyroiditis) was performed. T lymphocytes were purified from mononuclear cells extracted from surgically removed tissue. The following markers were evaluated: la antigens, MLR4 antigen (expressed on activated T cells) 5/9 antigen (expressed on a subset of lymphocytes containing the whole "helper-inducer" activity in vitro), Fc gamma-receptors, B9 antigen (expressed by cytotoxic, or precursor of cytotoxic, T cells). We observed increased percentages of 5/9-, MLR4- and la-positive T cells with respect to peripheral blood in both HT and GD: on the contrary, in specimens from nonautoimmune thyroid diseases mononuclear infiltrate was minimal, and even T cell evaluation was not possible. In addition, B9- and Fc gamma-positive T cells were increased in Hashimoto's, but not in Graves' thyroid tissue, thus suggesting a different role of cytotoxic effector mechanisms in the two diseases.

Incidence of T cell subset imbalance in relatives of Graves' disease patients

In previous reports we demonstrated imbalances of T cell subsets in patients with autoimmune thyroid disease. In the present investigation, we studied several T cell markers with different functional meaning (Fc gamma-receptors, HLA-Ia antigens, MLR4 and 5/9 antigens) in first degree relatives of Graves' disease patients. Our data suggest that imbalances of circulating T cell subpopulations are apparent only when abnormal hormone levels and/or thyroid autoantibodies are present.

Analysis of T cell subsets in Graves' disease: alterations associated with carbimazole

Conflicting data on subpopulations of peripheral blood lymphocytes in patients with autoimmune disease largely reflect variations in methods of study. An investigation was therefore conducted aimed at avoiding this difficulty. Serial samples of peripheral blood mononuclear cells from 42 patients with hyperthyroid Graves' disease were collected at monthly intervals before, during, and for 12 months after a six month course of carbimazole. Samples were stored in liquid nitrogen until completion of the study, when they were thawed and all samples from each patient analysed within the same assay using mouse monoclonal antibodies to human cell subsets and a fluorescence activated cell sorter. Proportions of cytotoxic/suppressor (OKT8) positive cells before treatment (mean 17.4 (SEM 0.8)%) were significantly lower (p less than 0.001) than those in normal controls (29.8 (1.9)%; n = 10) and returned to normal by the end of treatment. In contrast, the proportions of activated T cells (OKIa-OKM1) were significantly raised before treatment as compared with normal (14.4 (0.6)% versus 4.6 (0.8)%; p less than 0.001) and fell to normal by the end of treatment. Proportions of OKT3 and OKT4 positive T cells remained unchanged throughout treatment and in the succeeding 12 months. In patients who relapsed after treatment there was a rise in the proportion of activated T cells and a fall in OKT8 positive T cells, which returned towards normal with retreatment. The explanation for the alterations in numbers of circulating T cells remains to be determined but they may provide a means for predicting more accurately the outcome of Graves' disease after treatment with carbimazole.