Depletion of CD4+ and CD8+ cells eliminates immunologic memory of thyroiditogenicity in murine experimental autoimmune thyroiditis

Experimental autoimmune thyroiditis (EAT) develops in genetically susceptible mice after immunization with mouse thyroglobulin (MTg), and is mediated by T cells, both CD4+ and CD8+, infiltrating the thyroid. Previous work showed that depletion of CD4+, but not CD8+, cells with rat monoclonal antibodies (mAbs) interfered with EAT induction. To test if concomitant CD4+ cell depletion and immunization led to EAT resistance, mice were reimmunized at an interval of 15 or 43 days after injection of CD4 mAbs. No resistance had been established; disease severity and anti-MTg titers were comparable to mice with primary immunization. Previous work also showed that treatment during advancing EAT with only CD4 mAbs on days 21, 25 led to long-lasting, reduced severity in EAT, whereas administration of CD8 mAbs alone reduced the smaller CD8+ subset only. However, therapy with both mAbs was most efficacious; > 50% of thyroids were purged of all cellular infiltrate after only two doses. Moreover, T cells emerging subsequent to depletion were not retained in the thyroid, despite ongoing antibody production. To test if nondepleting CD4 and CD8 mAbs were similarly effective for therapy, mAbs of the IgG2a isotype were administered during advancing EAT. No effect on thyroidal infiltration was observed, indicating that modulation of the CD4 and CD8 antigen without depletion was insufficient for efficacious therapy. To determine if combined therapy with depleting mAbs reestablished self tolerance, treated mice were reimmunized on days 70, 77, when T cell recovery was nearly complete. Thyroiditis was comparable to controls given primary immunization, despite high antibody levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of thyroid stimulation blocking antibody without TSH receptor binding activity in rabbits with experimental autoimmune thyroiditis

When rabbits were immunized with porcine thyroid plasma membrane, some cases of produced antibodies showed the blocking activity for TSH stimulated cAMP production in cultured porcine thyroid cells in spite of negative TSH binding inhibitory immunoglobulin (TBII) activity. The inhibitory effect of these thyroid stimulation blocking antibodies (TSBAbs) on cAMP increase by forskolin and GTP gamma S in porcine thyroid cells was observed in 1 and 3 rabbits, respectively. When the blocking activity of these antibodies for stimulated cAMP production by forskolin, GTP gamma S and NaF was examined in the isolated porcine thyroid membrane, no blocking activity for these 3 stimulators except in 1 case was found. The blocking activity of these antibodies could be absorbed significantly by incubation with porcine thyroid plasma membrane as antigen. The blocking activity was not observed in rabbits immunized with porcine thyroglobulin. The present experiment demonstrated that the produced antibody in rabbits against porcine thyroid membrane had the blocking activity for TSH stimulation to thyroid cells without affecting TSH binding to its receptor. These facts suggest that this type of blocking antibody may be produced against any antigen of thyroid membrane origin except the TSH receptor.

Thyroglobulin antibodies in type 1 diabetic patients and their relatives--measurement with highly sensitive assay

Autoimmunity in Type 1 (insulin-dependent) diabetes mellitus was assessed by measuring thyroglobulin antibodies (TGA) using a highly sensitive enzyme immunoassay in 65 young patients with Type 1 diabetes mellitus, 83 healthy first-degree relatives of the patients, 37 healthy control subjects and 67 healthy parents of the control subjects. TGA were found in 78.5% (51/65) of patients and were significantly more frequent in patients than in control subjects (40.5%, 15/37; P < 0.01). The prevalence of TGA in patients showed no correlation with age at onset, duration of diabetes or sex. Among the first-degree relatives the prevalence of TGA was significantly increased in mothers of patients than in mothers of the control subjects (80.0% vs. 54.3%, P < 0.05), while not significantly between fathers of patients and fathers of control subjects or between siblings of patients and control subjects. Comparing the TGA levels of TGA-positive subjects, the TGA levels in patients, their parents and their siblings were significantly higher than those in the corresponding control subjects (P < 0.05, P < 0.05 and P < 0.01, respectively). In the present study we thus more clearly demonstrated autoimmune diathesis in patients with Type 1 diabetes and in their first-degree relatives.

Epitopes on thyroglobulin: a study of patients with thyroid disease

Thyroglobulin antibodies (TgAbs) are typically found in autoimmune thyroid diseases and, more rarely, in nonautoimmune thyroid diseases and healthy subjects. To determine whether TgAbs associated with different conditions recognize different epitopes on the thyroglobulin molecule, we studied 28 patients with Hashimoto's thyroiditis, 30 with Graves' disease, 21 with thyroid carcinoma, 18 with nontoxic goiter, and 25 healthy subjects. All patients were selected for the presence of TgAbs; 4/25 healthy subjects also had TgAbs. The sera were assayed for the their ability to inhibit the binding of monoclonal antibodies to thyroglobulin in an ELISA assay. We found that: 1) TgAbs in Hashimoto's patients preferentially recognized three clusters of epitopes (II, III and typically VI), with no difference between the goitrous and the atrophic variants; 2) TgAbs in Graves' patients were directed toward cluster II, with no difference between the presence or the absence of ophthalmopathy; 3) TgAbs in thyroid carcinoma patients recognized the same clusters as Hashimoto's patients; 4) TgAbs in nontoxic goiter patients and in the four healthy subjects showed no restriction in epitope recognition. We suggest that in individuals with no overt clinical or biochemical thyroid abnormalities but with TgAbs, the finding that these TgAbs recognize particular immunodominant clusters may be utilized to predict full-blown thyroid disorders. Longitudinal studies are needed to evaluate the possible clinical application of this methodology.

Distinct genetic pattern of mouse susceptibility to thyroiditis induced by a novel thyroglobulin peptide

Experimental autoimmune thyroiditis (EAT), induced by thyroglobulin (Tg) and adjuvant, is major histocompatibility complex-controlled and dependent on Tg-reactive T cells, but the immunopathogenic T-cell epitopes on Tg remain mostly undefined. We report here the thyroiditogenicity of a novel rat Tg peptide (TgP2; corresponding to human Tg amino acids 2695-2713), identified by algorithms as a site of putative T-cell epitope(s). TgP2 causes EAT in SJL (H-2s) but not in C3H or B10.BR (H-2k), BALB/c (H-2d), and B10 (H-2b) mice. This reveals a new genetic pattern of EAT susceptibility, since H-2k mice are known to be high responders (susceptible) after Tg challenge. Following in vivo priming with TgP2, T cells from only SJL mice proliferated significantly and consistently to TgP2 in vitro, whereas TgP2-specific IgG was observed in all strains tested. Adoptive transfer of TgP2-primed SJL lymph node cells to naive syngeneic recipients induced a pronounced mononuclear infiltration of the thyroid, which was more extensive than that observed after direct peptide challenge. TgP2 is non-immunodominant, since priming of SJL mice with rTg did not consistently elicit T-cell responses to TgP2 in vitro and a TgP2-specific T-cell hybridoma did not respond to antigen presenting cells pulsed with rTg. The data support the notion that Tg epitopes need not be either iodinated or immunodominant in order to cause severe thyroiditis and that the genetic pattern of the disease they induce can be distinct from that of Tg-mediated EAT.

Autoantibodies and monoclonal antibodies directed to an immunodominant antigenic region of thyroglobulin interact with thyroperoxidase through an interspecies idiotype

We investigated whether thyroglobulin (TG) autoantibodies (aAb) cross-react with thyroperoxidase (TPO) through an idiotypic structure using pooled normal human IgG (NhlgG) as a natural anti-idiotype reagent. Affinity-purified TG aAb from pooled IgG of patients with autoimmune thyroid disease were chromatographed on Sepharose-bound NhlgG. About one fourth of the loaded material bound to and eluted from the coupled gel. Eluted TG aAb were found reactive to TG and TPO and their TPO but not TG binding was strongly inhibited by molar excess of NhlgG. These TG aAb appeared to be mainly directed to an immunodominant TG antigenic region defined by TG monoclonal antibodies (mAb) from a single cluster of reactivity. These TG mAb were also found to recognize TPO and their binding to TPO but not TG was inhibited by molar excess of NhlgG as already observed with TG aAb. Taken together, these results indicated that TPO interacts with an idiotype present on human TG aAb and mouse TG mAb displaying a similar epitopic specificity; this interspecies idiotype is recognized by anti-idiotype antibodies present in NhlgG. Our results suggest that thyroid autoimmunity can be envisaged, at least in part, as a disturbance in interconnected idiotypic networks.

Studies of human thyroid xenografts from Hashimoto's thyroiditis in severe combined immunodeficient (SCID) mice: detection of thyroid stimulation-blocking antibody

Human thyroid xenografts from 7 patients with Hashimoto's thyroiditis (HT) and 3 normal persons (N) were xenografted into severe combined immunodeficient (SCID) mice to study the intrathyroidal lymphocytes that were expected to survive in these animals. Human IgG was detected in all mice engrafted with HT thyroid tissue peaking at 6-10 weeks after xenografting. Thyroperoxidase-antibody (TPO-Ab) was also detected in all mice with HT thyroid grafts peaking at 4-6 weeks after xenografting, reaching up to 44% of donors' original concentrations. In contrast, maximal thyroglobulin (Tg)-Ab production in some SCID mice with HT thyroid grafts was higher than the donors' original level, and was detectable in mice with thyroid grafts from Tg-Ab-negative HT donors. Thyroid stimulation-blocking antibody (TSBAb) was found in 2 mice with thyroid xenografts from 1 HT patient whose original serum TSBAb and thyrotropin-binding inhibitor immunoglobulin (TBII) had been positive; the maximal TSBAb level in SCID mice exceeded the donor's original level. TSBAb production in SCID mice reached its peak at 10 weeks after xenografting, i.e., later than that of thyroid-stimulating antibody (TSAb) observed in our recent report, suggesting the existence of distinct intrathyroidal B cell autoreactive clones of different life span responsible for secreting TSAb or TSBAb. When autologous peripheral blood mononuclear cells (PBMC) were engrafted alone (without thyroid tissue), TSBAb was undetectable.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroglobulin-specific T cell line from a healthy individual does not produce proinflammatory cytokines on antigenic stimulation: an implication for possible fail-safe mechanism to avoid autoimmunity

In order to investigate the regulation of autoimmune response to thyroglobulin (Tg), one of the thyroid autoantigens, we established a Tg-specific T cell line by stimulation of peripheral blood mononuclear cells from a healthy volunteer with Tg and characterized its cytokine production pattern. The Tg-specific T cell line, designated DH5D1, obtained from a limiting dilution culture bore alpha beta T cell receptor and was CD4 and CD45RO positive. Upon stimulation with Tg, DH5D1 secreted little or no titers of IL-2, TNF-alpha, and IFN-gamma, whereas activation with combination of phorbol myristate acetate and calcium ionophore produced measurable levels of these cytokines. These results indicate that the Tg-specific T cell line is not defective in its capacity to produce proinflammatory cytokines and suggest that the inability of cytokine production by autoreactive T cells of healthy individuals is one fail-safe mechanism for preventing aggression of harmful autoimmune response.

Interference of specific autoantibodies in the assessment of serum thyroglobulin

Prevalence of anti-thyroglobulin autoantibody (anti-TG Ab) above 120 IU/mL was 0.238 in 491 healthy and thyroid-disorder patients (80% female, mean overall age 50 +/- 15 years) presenting to the laboratory for contrastographic, endocrinologic, or general medical purposes. It is well known that anti-TG Ab (autoantibodies to thyroglobulin) can lead to the underestimation of serum thyroglobulin (TG). In this work, recovery (REC) of TG (thyroglobulin) added to the specimen was performed in all TG assays and low REC values were considered indicative of interference. The results show that REC = 70% is a very good cut-off value both for the anti-TG Ab prevalence found in our patients and in all prevalences below 0.6. However, we used an 80% cut-off which shows higher (+11%) sensitivity and in consequence improves the clinical decision. Only 60% of low REC values are directly attributable to high levels of anti-TG Ab. In the remaining 40%, low REC values are associated with low anti-TG Ab (< 120 IU/mL). These data indicate that anti-TG Ab concentrations are not always sufficient for evaluation of interference levels since they do not take account the actual effectiveness of anti-TG Ab. In fact, the same level of anti-TG Ab may reduce REC to different degrees (up to ten times) depending on the source serum. The practical consequence of this marked variability of autoantibody activity is that in the usual double Ab immunoassays REC must be determined for each sample to avoid unsuspected interference and negative influences on the clinical decision.(ABSTRACT TRUNCATED AT 250 WORDS)

The association of antithyroid antibodies in euthyroid nonpregnant women with recurrent first trimester abortions in the next pregnancy

OBJECTIVE

To evaluate the prognostic value of antithyroid antibodies in euthyroid women with a history of recurrent first trimester abortions on future pregnancy loss.

DESIGN

The sera of 42 euthyroid women with a history of three or more consecutive first trimester abortions were evaluated for the presence of antibodies to thyroglobulin and thyroid peroxidase before pregnancy and again as soon as the diagnosis of pregnancy was made.

SETTING

Medical school-affiliated private infertility center.

PATIENTS

Forty-two women with a history of three or more consecutive first trimester abortions who were planning to conceive again.

MAIN OUTCOME MEASURE

The presence of antithyroid antibodies in the nonpregnant state and their association with pregnancy loss in the next gestation.

RESULTS

Thirteen of 42 women (31%) were positive for the presence of antithyroid antibodies at the initial screening before pregnancy. All 13 maintained positivity by the time their next pregnancy was diagnosed. Only 12 of those 42 women (29%) experienced a first trimester abortion. Eight of these 12 women (67%) were positive for one or more antithyroid antibody. In contrast, among 30 nonaborting women, only 5 of 30 (17%) exhibited thyroid antibody positivity. The detection of thyroid antibodies before conception carried an increased risk of pregnancy loss in the next pregnancy (8 of 13, 62% versus 4 of 29, 14%).

CONCLUSION

The presence of antithyroid antibodies in nonpregnant women with a history of recurrent abortion identifies a subgroup of women at significantly increased risk for yet another pregnancy loss in their next gestation. Because organ-specific autoantibodies thus demonstrate similar prognostic significance to nonorgan-specific autoantibodies, it is tempting to conclude that peripheral autoantibody abnormalities seen in habitual aborters only reflect an underlying T-lymphocyte defect, which may be the actual cause of pregnancy loss.

Antibodies producing complement-mediated thyroid cytotoxicity in patients with atrophic or goitrous autoimmune thyroiditis

Thyroid-cytotoxic antibodies (thyroid-cytotoxic Abs) have been described in patients with autoimmune thyroiditis, but their role in the development of hypothyroidism remains to be clarified. In this study, we evaluated the pathogenetic role of thyroid-cytotoxic Abs in 20 patients with atrophic thyroiditis (idiopathic myxedema; AT) and 94 patients with goitrous Hashimoto's thyroiditis (HT). Among patients with HT, 27 were euthyroid (HT-E), 27 had subclinical hypothyroidism (HT-SH), and 40 had overt hypothyroidism (HT-H). Seventeen normal subjects and 8 patients with nonthyroidal illnesses were used as controls (C). To detect thyroid-cytotoxic Abs, human thyroid cells expressing thyroid peroxidase (TPO) were labeled with 51Cr and challenged with the immunoglobulin G (IgG) fraction of serum plus rabbit complement. The cytotoxic effect of IgGs was calculated as the percent specific lysis (% SL), taking into account the lytic effect of complement alone and the maximal lysis produced by a detergent. Most C-IgGs decreased the cytotoxic effect of complement (median % SL, -3.3). IgGs from hypothyroid patients with thyroiditis had a greater cytotoxic effect than C-IgGs, either as a whole group (P < 0.001), or when subdivided according to clinical diagnosis: HT-SH (median % SL, 4.8; P < 0.005), HT-H (%SL, 2.2; P < 0.0001), or AT (%SL, 0.9; P < 0.01). Among patients with HT, the lytic activity of IgGs from patients with subclinical and overt hypothyroidism was higher than that of IgGs from euthyroid patients (P < 0.05). The results of IgGs from euthyroid patients with HT (median % SL, -0.9) did not significantly differ from those of C-IgGs. By taking a cut-off over the upper range of % SL produced by C-IgGs (> 2), the prevalence of thyroid-cytotoxic Abs was 30% in AT, 59% in HT-SH, and 55% in HT-H. However, 37% of euthyroid patients with HT also had thyroid-cytotoxic Abs. No IgG containing TPO antibodies (TPOAb) at low titer (< 40(2)) was cytotoxic. However, the levels of thyroid-cytotoxic Abs did not correlate with TPOAb titers, and preabsorption with TPO only partially abolished the lytic effect of some HT-IgG. These findings suggest that TPO is a target of thyroid-cytotoxic Abs, but other thyroid antigens are also involved in the cytotoxic reaction.(ABSTRACT TRUNCATED AT 400 WORDS)

The detection of antithyroglobulin activity in human serum monoclonal immunoglobulins (monoclonal gammopathies)

The sera of 159 patients with monoclonal gammopathies were examined for the presence of anti-thyroglobulin (Tg) activity. An enzyme-linked immunosorbent assay was employed. Thirty-one (19.5%) sera were found to bind Tg. The activity against Tg was further confirmed by using purified immunoglobulins and employing competition assays. The anti-Tg antibodies were found in the sera of patients with IgG, IgM and IgA gammopathies. Anti-Tg antibodies were more frequent among patients with IgG gammopathy. Autoantibodies to Tg are found in patients with Hashimoto's thyroiditis, Graves' disease and occasionally in patients with thyroid carcinoma. Natural autoantibodies directed against human Tg have been detected, as well, in healthy subjects. None of the patients in the present study whose serum was found to contain high titers of anti-Tg human monoclonal antibodies had any clinical or biochemical evidence of thyroid disease. Our results of a high incidence of anti-Tg activity in the sera of patients with monoclonal gammopathies support previous reports of autoantibody properties characteristic of these immunoglobulins.

Monoclonal anti-idiotypic antibodies against human anti-thyroglobulin autoantibodies recognize idiotopes shared by disease-associated and natural anti-thyroglobulin autoantibodies

Monoclonal murine anti-idiotypic antibodies generated against purified human anti-thyroglobulin (TG) antibodies from a patient with Hashimoto's thyroiditis recognized two major clusters of idiotopes (1C2 and 1B1) on human anti-thyroglobulin antibodies which were framework and paratope-related. A survey of affinity-purified autoantibodies from Hashimoto's patients indicated that the 1C2 and 1B1 idiotopes are expressed on the disease-associated anti-TG antibodies from several patients. 1C2 and 1B1 idiotopes are also detected on affinity-purified anti-TG antibodies isolated from serum of healthy donors and with therapeutic preparations of immunoglobulins obtained from plasma pools of healthy individuals. The observation that both framework and paratope-related idiotopes are shared by natural and patients' autoantibodies suggests that the anti-TG autoantibodies found in sera of patients with Hashimoto's disease represent an abnormal expansion of normal autoreactive B cell clones rather than the emergency of an antigen-driven, disease-specific B cell response.

Characterization of a thyroiditis-inducing thyroglobulin-specific T-cell clone restricted by the H-2 molecule of a low responder mouse strain

We established a thyroglobulin (Tg)-specific, thyroiditis-inducing T-cell clone, B12G, from B6C3F1 mice by the immunization of mouse Tg with lipopolysaccharide (LPS) from Klebsiella strain LEN (O3:K1). B12G was Thy-1.2+, CD3+, CD4+, CD18+, and CD8-, and could transfer thyroiditis to recipient mice after in vitro stimulation with mouse or bovine Tg. Histological examination showed severe thyroiditis with predominant infiltrations of polymorphonuclear cells; few mononuclear cells were observed. B12G proliferated in response to bovine, mouse, porcine, and rat Tg in the presence of irradiated spleen cells, but did not respond to chicken or human Tg. H-2b, a low-responder haplotype of experimental autoimmune thyroiditis, governed the response of the clone to Tg. B12G produced interleukin-4 (IL-4) and IL-6, but not IL-2 or interferon-gamma (IFN-gamma), on stimulation with mouse Tg. These findings were different from characteristics of previously reported Tg-specific T-cell clones from high-responder mice in terms of epitope specificity and cytokine production pattern, raising the possibility that the specificities and functions of T cells involved in the development of autoimmune thyroiditis in low-responder mice differ from those in high responders.

Selection of the expressed B cell repertoire by infusion of normal immunoglobulin G in a patient with autoimmune thyroiditis

In the present study we have analyzed the changes in the expressed antibody repertoire and in temporal fluctuations of antibody levels in serum that followed infusion of normal IgG (IVIg) in a patient with autoimmune thyroiditis. Administration of IVIg resulted in the stimulation of IgM production, in alterations of expressed antibody activity in serum that could not merely be accounted for by the passive transfer of antibody specificities contained in IVIg, in transient down-regulation of B cells clones expressing a specific disease-related idiotype and in the increase in serum in recipient's autoantibodies specifically reactive with F(ab')2 fragments of IVIg. In addition, infusion of IVIg shifted the pattern of spontaneous fluctuations of autoantibody activities in the patient's serum from a pattern indicative of disconnected events in the immune network to a pattern similar to that which is consistently observed in healthy controls. These results suggest that normal IgG may modulate autoreactivity by selecting expressed antibody repertoire through V region-dependent interactions with antibodies.

Adhesion molecule monoclonal antibodies inhibit experimental autoimmune thyroiditis

To examine the role played by adhesion molecules in thyroid autoimmunity, we have assessed the effect of administering monoclonal antibodies (mAb) against intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) in experimental autoimmune thyroiditis, induced by immunizing rats with thyroglobulin in complete Freund's adjuvant. The antibody against LFA-1, but not against ICAM-1, reduced thyroglobulin antibody production (P < 0.01) and both antibodies caused a significant reduction (P < 0.002) in the severity of the thyroidal lymphocytic infiltration. In vitro, both mAb impaired the proliferative response of splenic and lymph node T cells to thyroglobulin, but only the antibody against LFA-1 reduced thyroid cell killing assessed using splenic lymphocytes as effectors. Monoclonal antibodies against both these adhesion molecules appear to inhibit cell-mediated autoimmunity in vivo, but only the LFA-1 mAb reduced the autoantibody response.

Complex alteration of thyroid function in healthy centenarians

Several changes in thyroid function have been described in the elderly and largely attributed to concomitant nonthyroidal illness. The extent to which aging per se contributes to these changes remains to be elucidated, and scanty data are available in extremely old subjects. The present study was designed to focus on thyroid function during physiological aging, taking advantage of two groups of selected aged individuals: group A of healthy centenarians (n = 41; age range, 100-110 yr) and group B including healthy elderly subjects selected by the criteria of the EURAGE SENIEUR protocol (n = 33; age range, 65-80 yr). Control groups included 98 healthy normal adult subjects (group C; age range, 20-64 yr) and 52 patients with miscellaneous nonthyroidal illness (group D; age range, 28-82 yr). Our previous report of a low prevalence of thyroid autoantibodies in centenarians was confirmed and extended by the finding of a similar low autoantibody prevalence in the highly selected healthy elderly population of group B. Subclinical primary hypothyroidism was found in 3 (7.3%) centenarians, and their data were excluded from further statistical evaluation. No significant difference was found in the median serum free T4 levels of groups A-C. Median (and range) serum free T3 (FT3) was lower in centenarians [3.67 pmol/L (2.3-5.5)] than in group B [5.22 pmol/L (3.4-6.1)] and group C [5.38 pmol/L (2.9-8.4); P < 0.0001 vs. both groups]. Similarly, the median serum TSH level of centenarians [0.97 mU/L (< 0.09 to 2.28)] was lower than those in groups B [1.17 mU/L (0.53-2.74)] and C [1.7 mU/L (0.4-4.8); P < 0.0001 vs. both groups]; moreover, serum TSH was also significantly (P < 0.01) lower in group B than in group C. Both serum FT3 and TSH concentrations showed a significant inverse correlation (r = -0.634; P < 0.0001 and r = -0.377; P < 0.0001, respectively) with age. Median serum FT3 in centenarians was lower than that in group D patients [4.61 pmol/L (2.15-6.6); P < 0.0001]. In contrast, median serum rT3 in centenarians [0.40 nmol/L (0.20-0.77)], although higher than those in groups B [0.24 nmol/L (0.15-0.37); P < 0.0001] and C [0.22 nmol/L (0.05-0.46); P < 0.0001], was significantly lower than that in group D [0.60 nmol/L (0.13-2.08); P < 0.0001]. In conclusion, thyroid function appears to be well preserved until the eighth decade of life if healthy subjects are studied, whereas a reduction of serum FT3 is observed in extreme aging.(ABSTRACT TRUNCATED AT 400 WORDS)

Difference in clinical features and HLA antigens between familial and non-familial vitiligo of non-segmental type

Of 131 patients with non-segmental vitiligo studied, 29 (22%) had a family history of this disorder. The clinical features and HLA antigens were assessed, and a comparison made between patients with familial and those with non-familial, non-segmental vitiligo. Familial patients developed skin lesions significantly earlier than non-familial patients. There was a significant association between HLA-B46 and familial non-segmental vitiligo, whereas HLA-A31 and CW4 were found in non-familial patients. The differences in clinical features and HLA phenotypes suggest heterogeneity in the pathogenic process between familial and non-familial vitiligo patients.

Characterization of resistance to murine experimental autoimmune thyroiditis: duration and afferent action of thyroglobulin- and TSH-induced suppression

Genetically susceptible mice develop experimental autoimmune thyroiditis (EAT) after immunization with mouse thyroglobulin (MTg). Earlier studies have shown that resistance to EAT induction can be activated by two regimens, pretreatment with deaggregated MTg (dMTg) or with thyroid-stimulating hormone (TSH). With both protocols, suppression is linked to a > or = 2-3 day increase in circulatory MTg level and is mediated by CD4+ suppressor T cells (Ts). To assess the duration of suppression, CBA (H-2k) mice were injected with dMTg or infused with TSH via an osmotic pump for 3-4 days and then challenged with MTg + adjuvant at intervals up to 73 days for dMTg-pretreated mice or up to 94 days for TSH-pretreated mice. Suppression was measurable for at least 73 days after injected dMTg. TSH-induced suppression was also long-lasting; resistance was strong 38 days after TSH infusion and was still measurable on Day 66. The Thy-1+, CD4+ Ts which transfer MTg-induced suppression were further characterized by treatment with I-J antibodies plus complement prior to transfer. This treatment abolished the transfer of suppression which acts in the afferent phase to interfere with EAT induction. The capacity of Ts to suppress the efferent phase of EAT was assessed in vitro and in vivo. Cells from dMTg-pretreated mice did not block the in vitro proliferative response of MTg-primed cells to MTg, nor did these cells, when left intact in situ, reduce the severity of disease produced by the adoptive transfer of thyroiditogenic cells. Similarly, TSH-induced suppression was ineffective in preventing adoptively transferred EAT. Since suppression, which correlates with a temporary increase of circulatory MTg, occurs only at the afferent phase of active immunization, these findings lend support to our earlier hypotheses that circulatory MTg serves a physiologic role in maintaining normal self-tolerance by sustaining low levels of Ts activation and that additional rise above baseline increases and prolongs resistance to EAT induction.

Age-related changes in specificity of human natural autoantibodies to thyroglobulin

We have analysed the epitopic and idiotypic specificity of thyroglobulin antibodies in infants, young adults, aged subjects and pregnant women in order to evaluate the changes that occur in the autoantibody repertoire with age in physiological situations. No increase in IgG anti-Tg autoreactivity in whole serum and purified IgG from serum was observed with aging. However, IgG from elderly individuals exhibited increased reactivity, as compared to other groups of donors, against particular epitopes commonly recognized by both natural and disease-associated Tg-autoantibodies. The acquisition of a distinct epitopic reactivity in aged individuals suggests that qualitative rather than quantitative criteria could characterize alteration in regulation of the autoreactive B-cell repertoire that occurs with aging. No correlation was observed between the age of the donors and expression of a thyroid disease-associated idiotype (T44 Id) by hTg-autoantibodies. The expression of T44 Id on IgG obtained from serum of a small number of pregnant women may be an effect of the modifications of immune system function in pregnancy, which could lead to increased incidence of autoimmunity during pregnancy or in the post-partum period.

Reduced activation of suppressor T lymphocytes by specific antigens in autoimmune thyroid disease

In order to study the activation of suppressor T lymphocytes by thyroid-specific antigens in autoimmune thyroid disease (AITD), we have investigated the effects of the organ-specific antigens, thyroperoxidase (TPO), thyroglobulin (Tg), and thyroid microsomal antigen (TMc), as well as renal microsomes (RMc) as a control antigen, on the activation of suppressor T lymphocytes; this was accomplished by measuring major histocompatibility complex class II (HLA-DR) expression on their surfaces by flow cytometric analysis. Peripheral blood mononuclear cells (PBMC), obtained from 33 patients with Graves' disease (GD), 26 with Hashimoto's thyroiditis (HT), 5 with nontoxic nodular goiter (NTG), and 30 normal persons (N), were cultured for 7 days in the presence or absence of TPO, Tg, or RMc at final concentration of 10, 100, and 1000 ng/ml. Cultured cells were stained with fluorescent-conjugated monoclonal antibodies (anti-CD8, anti-CD11b, and anti-HLA-DR), and the activation of CD8+ and CD8+CD11b+ (pure suppressor) T cells by the antigens was analyzed on a flow cytometer. In the absence of antigen, i.e., the autologous mixed lymphocyte reaction (AMLR), CD8+ and CD8+CD11b+ T lymphocytes from patients with GD and HT showed significantly lower activation as compared to N. We measured the Stimulation Index (Sl) of activated T lymphocytes to compare antigen-specific activation between CD8+ and CD8+CD11b+ cells from normal persons and patients. With stimulation of 100 and/or 1000 ng/mL of TPO or Tg, Sl of activated CD8+ cells was significantly (p < 0.05 to 0.01) lower in GD and HT as compared with N.(ABSTRACT TRUNCATED AT 250 WORDS)

Post partum thyroiditis in Saudi women

Two hundred and seventy seven Saudi women were prospectively evaluated post-partum to determine the frequency of post-partum thyroiditis. Four to six weeks after delivery, 12 (4.3%) had positive antimicrosomal antibodies and 8 (2.9%) had positive antithyroglobulin antibodies. At 6-8 weeks post-partum, out of 82 subjects followed up, 4 (4.9%) had positive antimicrosoMal antibodies and 1 (1.2%) had positive antithyroglobulin antibodies. At 8-12 weeks post-partum, out of 70 subjects, antimicrosomal antibodies were detected in 5 (3.5%) subjects and antithyroglobulin in 2 (1.4%). Their routine thyroid function tests (T3, T4, and TSH) remained within the normal range. There was no clinical evidence of hyper- or hypothyroidism in any of the patients during the follow up. Post-partum thyroiditis, appears to be relatively uncommon in Saudi Arabia. It does not produce any clinical illness or cause significant subclinical thyroid dysfunction.

Immunotargeting of thyroglobulin on antigen presenting cells abrogates natural tolerance in the absence of adjuvant

Mice usually develop strong IgG responses to self-thyroglobulin (Tg) following immunization with mouse Tg (mTg) emulsified in complete Freund's adjuvant (CFA). Here we report that adjuvant-free challenge of mice with small doses of mTg conjugated onto a monoclonal antibody (MAb) specific for class II MHC determinants (anti-I-Ak) induces an mTg-specific IgG response in CBA (H-2k) but not in B6 (H-2b) mice. This is not a result of nonspecific uptake of immunoconjugate or chemical modification of mTg because mTg conjugated in a similar manner to a control MAb (specific for influenza nucleoprotein) of the same IgG subclass as the anti-I-Ak MAb did not elicit an autoimmune response. Despite the presence of mTg-specific IgG with titers equal to those observed after challenge with mTg in CFA, thyroid lesions were not detected in CBA mice that received mTg-(anti-I-Ak Mab) conjugate indicating a clear divergence in the requirements for autoantibody production and disease. The data suggest that small amounts of soluble autoantigen, conjugated onto MAbs specific for determinants expressed on antigen-presenting cells (APC), can effectively abrogate natural tolerance perhaps via a targeting mechanism that focuses autoantigen on APC. This approach may help elucidate the role of various APC subsets in autoimmunity and allow the study of initial events that trigger autoreactivity outside a CFA-induced granuloma site.

Human lymphocyte antigens (HLA) and Graves' disease in Turkey

To evaluate the association of HLA types with Turkish patients with Graves' disease, HLA typing, clinical findings, and thyroid antibodies were correlated. The HLA types, clinical findings (ophthalmopathy and age at onset), and thyroid stimulating hormone (TSH) receptor (TRAb) and antithyroid microsomal antibodies (MAb) were analyzed. Seventy Turkish patients with Graves' disease and 306 control subjects were assessed. Serological HLA typing was performed in HLA A, B, C, DR, and DQ loci. There was a significantly increased prevalence of HLA B8, B49, DR3, DR4, and DR10 in Graves' disease. The association of Graves' disease with HLA DR3 was found to be less strong than previously described. The HLA DR4 antigen may contribute to the predisposition of Graves' disease in Turkey. The results suggest that HLA B7, B13, DR7, DQw2, and DQw3 may confer a protective effect for Graves' disease in Turkey. Patients carrying HLA B12, B18, and B44 haplotypes had a tendency to develop the disease at a later age. The difference from the other studies may be the result of the selection of the controls; in part, of the variability in serological typing reagents; and, also, of the rather weak HLA associations with the disease.

Antibody-induced alterations of Na+/K(+)-ATPase activity in rabbit red blood cells during experimental thyroglobulin immunization

Thyroid hormone modulates cell membrane Na+/K(+)-ATPase. A detailed study of erythrocyte membrane Na+/K(+)-ATPase activity was carried out during experimental thyroglobulin immunization. During the process of immunization there was a sharp decline in Na+/K(+)-ATPase activity until the 98th day of immunization, when the thyroglobulin antibody titer was at its peak. This enzyme activity retained a lower level although a fall in antibody titer occurred up to the 147th day.