A common T-cell epitope between human thyroglobulin and human thyroid peroxidase is related to murine experimental autoimmune thyroiditis

We have investigated functional common T-cell epitopes between human thyroglobulin (hTg) and human thyroid peroxidase (hTPO) in mice. Four hTg peptides, Tg-P1, Tg-P2, Tg-P3 and Tg-P4, in which 5 amino acid residues are identical to those of hTPO, and 1 hTPO peptide, TPO-P4 relevant to Tg-P4, were prepared. Among these peptides, only Tg-P4 (residues 2730-2743) and TPO-P4 (residues 118-131) were highly antigenic and both peptides shared the common T-cell epitope. In addition, when the spleen cells from mice immunized with mouse Tg (mTg) were restimulated in vitro by Tg-P4 or TPO-P4 as well as by mTg, these cells transferred thyroiditis to naive recipient mice. These findings indicate that this common T-cell epitope between hTg and hTPO is immunogenic and related to the development of murine experimental autoimmune thyroiditis.

Monoclonal antibodies that recognize the trisaccharide epitope Gal alpha 1-3Gal beta 1-4GlcNAc present on Ehrlich tumor cell membrane glycoproteins

Monoclonal antibodies were prepared against the trisaccharide Gal alpha 1-3Gal beta 1-4GlcNAc, a sequence which occurs on the surface of Ehrlich ascites tumor cells as well as in thyroglobulin, laminin and a variety of other proteins. This was accomplished by immunizing BALB/c mice with the fraction of Ehrlich cell membrane glycoproteins obtained by affinity chromatography on a Griffonia simplicifolia I (GS I) column which selectively binds alpha-D-galactosyl-terminated structures. Detection of Gal alpha 1-3Gal beta 1-4GlcNAc-specific antibodies was accomplished by employing glycoproteins containing the trisaccharide sequence; fusion with spleen cells from an immunized mouse was accomplished in the presence of polyethylene glycol (PEG1500). An enzyme-linked immunosorbent assay (ELISA) system was used to identify two clones (2.10G and 6.8E), which recognized the desired trisaccharide conjugate. These clones also recognized a thyroglobulin fraction isolated by GS I affinity chromatography and murine laminin, both of which possess the Gal alpha 1-3Gal beta 1-4GlcNAc sequence. Inhibition of antibody-trisaccharide reactivity, examined employing an ELISA assay, revealed that two trisaccharides, Gal alpha 1-3Gal beta 1-4GlcNAc/Glc, were the best inhibitory haptens; Gal beta 1-4GlcNAc (LacNAc), Gal alpha 1-3Gal and Gal beta 1-4Glc (lactose) were poor inhibitors. Indirect immunofluorescence staining of unfixed Ehrlich cells using the monoclonal antibody at 4 degrees C revealed fluorescence over the entire cell surface. Indirect immunogold labeling of semithin and ultrathin sections of aldehyde fixed and Lowicryl K4M-embedded Ehrlich cells resulted in specific labeling of the cell surface and internal structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyreactivity is a property of natural and disease-associated human autoantibodies

Polyreactivity was earlier recognized as a feature of naturally expressed autoantibodies in serum. In the present study, we have compared the reactivity on a panel of self antigens of affinity-purified anti-DNA and anti-thyroglobulin (TG) IgG autoantibodies from the serum of patients with systemic lupus erythematosus (SLE) and autoimmune thyroiditis with their affinity-purified counterparts isolated from the serum of healthy individuals. Anti-DNA autoantibodies exhibited a similar degree of polyreactivity whether originating from patients or from healthy adults. Natural anti-TG autoantibodies were also found to be polyreactive. Anti-TG autoantibodies from patients with Hashimoto's thyroiditis showed little or no polyreactivity. Natural anti-TG autoantibodies were equally polyreactive whether or not they belonged to a fraction of normal IgG that is connected through V regions with other IgG molecules from the same source. These results indicate that polyreactivity of autoantibodies is a feature that does not allow one to distinguish between natural and disease-associated autoantibodies as well as between V-region-connected and unconnected autoantibodies.

Development, characterization and application of an antibody against 5-fluoro-2'deoxyuridine-5'monophosphate, the active metabolite of 5-fluorouracil

5-Fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP) is the active metabolite of the anticancer agent 5-fluorouracil (5FU). Antibodies against a conjugate of thyroglobulin with acetylated FdUMP were raised in 4 rabbits. The maximal titer was reached after 3-5 boosters. Subsequently, the antisera were collected and partially purified. In a competition assay a 100-fold excess of the natural nucleotide dUMP could displace tritiated FdUMP (20 pmol per assay) by about 50% in all antisera. However, tritiated dUMP itself did not bind to the antibody. No cross-reactivity was observed with the FdUMP precursor 5FU and with the natural nucleoside uridine and the nucleotides dTMP, dTTP and UTP. A considerable cross-reactivity was observed with the monophosphate of bromodeoxyuridine (Br-dUMP). Radio-immuno assays for FdUMP and dUMP were developed, for which a 100-fold dilution could be used. The FdUMP assay was linear in a range of 0.1 to 5 pmol FdUMP in aqueous solutions. Tumour samples contained a non-identified interfering factor; a similar interference was observed in an enzyme based assay for FdUMP. The dUMP assay was performed by competition of unlabeled dUMP with tritiated FdUMP and was linear from 50 to 2000 pmol dUMP per assay. The antibody recognized FdUMP bound in a ternary complex synthesized in a cell-free system between FdUMP, its target enzyme thymidylate synthase and the folate co-factor. Immunohistochemical staining for demonstration of the ternary complex in 5FU treated cells and tumours from patients and animals was not yet successful, neither with peroxidase nor with immunofluorescence staining. Possibly the amount of bound FdUMP is below the detection limit or FdUMP bound to TS is masked. The antibody may prove to be useful in studies on modulation of FdUMP and dUMP after treatment with thymidylate synthase inhibitors.

Studies of thyroid xenografts from Graves' disease in severe combined immunodeficient mice

Thyroid tissues from normal (paranodular) subjects and patients with Graves' disease (GD) and Hashimoto's thyroiditis (HT) were xenografted to severe combined immunodeficiency (SCID) mice, and the same tissues were engrafted into nude mice; in addition, peripheral blood mononuclear cells were engrafted to separate SCID mice (SCID-PB). Thyroglobulin (TG) and microsomal antibodies (Abs) became detectable with high titers by hemagglutination assays in SCID mice xenografted with thyroid tissues (SCID-TH) from GD and HT patients; moreover, TG Ab was detectable even in SCID-TH from TG Ab-negative GD and HT donors. On the other hand, only 2 of 10 SCID-PB had detectable Abs with low titers. TSH receptor (TSH-R) Ab was detectable in all sets of SCID-TH from GD. After peaking (3-7 weeks), their levels decreased despite the fact that immunoglobulin G levels increased. In addition, in 3 of 4 sets of SCID-PB from GD patients, TSH-R Ab was also detectable. SCID-TH from GD and HT patients showed transient hyperthyroxinemia, peaking at 2 weeks; these values were significantly higher [free T4, 6.48 +/- 0.90 and 5.50 +/- 0.77 pmol/L (mean +/- SE), respectively; P < 0.05] than SCID-TH from normal controls (2.5 +/- 0.24). Histologically, intrathyroidal infiltrating lymphocytes (ITL) survived in SCID mice, but not in nude mice after 8 weeks. The follicles of GD tissue in SCID mice were virtually destroyed with ITL, and their appearance was similar to that in HT. In conclusion, TSH-R Ab was clearly produced from ITL, and some peripheral blood mononuclear cells grafts could also produce TSH-R Ab. In spite of the presence of TSH-R Ab, SCID-TH from GD patients did not show persistent hyperthyroxinemia, presumably because destructive thyroiditis may be occurring in the grafted tissue, with decreasing levels of TSH-R Ab.

Extremely high titre polyclonal antisera against small neurotransmitter molecules: rapid production, characterisation and use in light- and electron-microscopic immunocytochemistry

We have produced polyclonal antibodies against the small amino acid neurotransmitters, GABA, glutamate, glycine and taurine, with a simple new technique using antigens co-adsorbed with an adjuvant peptide to gold particles, which causes rapid and massive immune responses in all animals that we have studied. These antibodies are all of extremely high titre; they are typically used in immunocytochemistry at dilutions from 1 in 250,000 to 1 in 1,000,000 which represents an increase in titre of at least two orders of magnitude compared to standard antibody production techniques. Such very high dilutions result in minimal background labeling and a high signal-to-noise ratio when applied to sections of aldehyde-fixed, epoxy resin-embedded tissues at both light- and electron-microscopic levels. Each antibody displays minimal cross-reactivity with other neurotransmitter molecules. We suggest that our technique may be broadly applicable for raising antibodies against a wide variety of antigens of interest to neuroscientists, particularly those that normally elicit weak immune responses. The technique may also assist in clonal expansion prior to generation of monoclonal antibodies and may be viable, with modifications, for use in human immunisations.

A thyroid cancer specific monoclonal antibody which recognizes cryptic epitope(s) of human thyroglobulin

A monoclonal antibody (TCM-9) specific for human thyroid cancer but not for Graves' disease, adenoma or normal thyroid tissue was shown to recognize a 300 K protein but not to bind to native or mature human thyroglobulin (Tg). In this study, we investigated further the antigen recognized by TCM-9. When purified Tg was treated with periodate, dithiothreitol (DTT) and sodium dodecyl sulfate (SDS), immunoblotting of treated Tg with TCM-9 revealed an apparent enhancement of the staining only with DTT-treated Tg. Furthermore, the DTT-treated Tg was shown to bind dose-dependently to plates coated with TCM-9. We performed SDS-PAGE and immunoblot analyses on the immune complex obtained from a homogenate of thyroid cancer tissue which was preincubated with an excess of anti-Tg monoclonal antibody. When the protein was autoradiographed with [125I]TCM-9, a definite band was observed. The results indicate that TCM-9 is likely to be directed against a masked epitope of thyroglobulin which can be exposed after treatment with a reducing agent.

Interleukin-2-induced thyroid dysfunction is correlated with treatment duration but not with tumor response

PURPOSE

To analyze the putative relationship between immunotherapy-associated dysthyroidism and the probability of a tumor response.

PATIENTS AND METHODS

A total of 89 consecutive patients with advanced cancer were treated with interleukin-2 (IL2)-based immunotherapy in a prospective study.

RESULTS

Twenty patients developed thyroid dysfunction. Repeatedly positive tests for thyroid antibodies developed in 28% of the patients. Twenty-two patients achieved a response. There was no relationship between the formation of antibodies and the probability of response. There appeared to be a trend toward a relationship between thyroid dysfunction and response (P = .23). A strong relationship was found between response on the one hand and cumulative dose of IL2 (P = .01) and treatment duration with IL2 (P = .025) on the other. The frequency of thyroid dysfunction was also significantly correlated with treatment duration (P = .001). After adjustment for cumulative dose of IL2 and treatment duration, no relationship between thyroid dysfunction and response remained (P = .99).

CONCLUSION

There is no relationship between thyroid dysfunction and the probability of tumor response. Thyroid dysfunction is merely a function of treatment duration and cumulative dose of IL2.

Induction of experimental autoimmune thyroiditis in rats with the synthetic peptide (2495-2511) of thyroglobulin

We have previously shown that the synthetic 17 mer peptide TgP1 (a.a. 2495-2511) from the rat thyroglobulin (Tg) sequence is thyroiditogenic in mice and consists of nonimmunodominant but highly immunogenic determinants at the T or B cell level. Although TgP1 appears to be phylogenetically conserved, it remains uncertain whether it is a self-peptide in mice since the mouse Tg amino acid sequence is unknown. In this report, we demonstrate that TgP1 also induces experimental autoimmune thyroiditis (EAT) in WKY, F344, and WF strains of rats that are known to be EAT-susceptible after Tg challenge. Priming of all strains with TgP1 led to strong proliferative lymph node cell responses to the peptide in vitro that were abrogated by MAbs against CD4, OX-6, and OX-17 determinants, suggesting TgP1 recognition by class II-restricted T cells. In vivo priming with autologous or heterologous Tg did not lead to TgP1-specific proliferation in vitro confirming the cryptic nature of this sequence in rats. In contrast to findings in the mouse, strong peptide-specific IgG responses were not observed in rats despite the presence of EAT. These data demonstrate that TgP1 is immunopathogenic in an autologous system and provide the first evidence of a defined autoantigenic Tg peptide in rats.

The superiority of antimicrosomal over antithyroglobulin antibodies for detecting Hashimoto's thyroiditis

BACKGROUND

Antimicrosomal (anti-M) and antithyroglobulin (anti-Tg) antibodies are commonly measured together to detect Hashimoto's thyroiditis. Since this nearly doubles the cost of testing for one antibody, we wished to determine whether significant diagnostic loss would occur if the two tests were replaced by anti-M alone.

METHODS

Both tests were performed in 2030 consecutive patients referred by general internists and endocrinologists.

RESULTS

With a positive result defined as either test being positive at a 1:100 dilution, anti-M was much more sensitive than anti-Tg. Anti-M was positive in 99% (823/831) of all patients with positive tests, while anti-Tg was positive in 36% (302/831). Anti-M was the only positive test in 64% of all patients with positive tests, while anti-Tg was the only positive test in 1%. With a cutoff point of 1:400 dilution, the results were similar.

CONCLUSIONS

Anti-M alone appears sufficient to detect autoimmune thyroid disease at about one half the cost of routinely performing both anti-M and anti-Tg studies. The widespread practice of performing both tests increases the cost without an offsetting diagnostic gain.

Active suppression induced by anti-CD4

Treatment with a non-depleting monoclonal antibody to CD4 in the presence of mouse thyroglobulin (MTg) inhibits the development of murine autoimmune thyroiditis. This unresponsiveness was transferrable since such treatment generated a population of donor cells which could suppress the thyroiditis induced in lightly irradiated recipients by subsequent challenge with specific antigen. The suppression appears to be both antigen specific and antigen dependent and seems to discriminate between TH1 and TH2 helper subsets in that there is no significant effect on anti-MTg autoantibodies after challenge.

Quantitative measurement of human thyroglobulin-specific antibodies by use of a sensitive enzyme-linked immunoassay

A quantitative enzyme-linked immunoassay that measures in absolute terms the subclass concentration of human thyroglobulin (huTg)-specific IgG autoantibody was developed. Unique to this study was the use of an affinity-purified anti-huTg standard with a known concentration of the four IgG subclasses. The sensitivity of the ELISA assay was 1-5 ng/ml depending on the IgG subclass being measured. We examined 22 sera of patients with autoimmune thyroid disease. The total huTg-specific antibody concentrations in serum ranged from 0 to nearly 3000 micrograms/ml of IgG. The IgG subclass distribution in individuals with low huTg-specific IgG (< 10 micrograms/ml) was primarily IgG1 and IgG3 Ab. Patients with intermediate levels of huTg IgG (10-600 micrograms/ml) expressed all four subclasses; however, no particular subclass was dominant. Individuals with > 1000 micrograms/ml also showed huTg-Ab in all four subclasses, however, IgG1 and IgG2 were dominant. All four IgG subclasses were used in the response to huTg, although the pattern of usage varied between individuals. There was no dominant subclass usage seen in this patient population.

Fetal growth and autoimmune thyroid disease

To determine whether fetal and infant growth could influence susceptibility to autoimmune disease in adults, the occurrence of thyroid autoantibodies and autoimmune thyroiditis was studied in 305 women, aged 60-71, born in Hertfordshire and for whom details of birthweight, infant growth, and feeding were routinely recorded. Thyroglobulin autoantibody was detected in 37% of the women, thyroid peroxidase autoantibody in 41%, and autoimmune thyroiditis, defined as biochemical or clinical hypothyroidism in association with thyroid autoantibodies, in 5.6%. The proportion of women with thyroglobulin and thyroid peroxidase autoantibodies fell with increasing birthweight but was not related to weight at 1 year of age or the method of infant feeding. The prevalence of both autoantibodies rose with increasing adult body mass index but fell as the waist to hip ratio increased. These results demonstrate the importance of early environment in determining the susceptibility to autoimmune thyroid disease. The contrasting effects of adult body mass index and waist to hip ratio on antibody prevalence could be explained by their associations with different hormonal environments.

Generation of human monoclonal antibodies by transformation of lymphoblastoid B cells with ras oncogene

Human monoclonal antibodies (hu-mAbs) of predetermined specificity and isotype are potentially important for a variety of applications, including therapy and diagnosis. Their efficient generation, however, is still hampered by technical difficulties. Even the most established approaches to the generation of hu-mAbs, i.e., B cell immortalization by Epstein-Barr virus (EBV) and/or fusion with appropriate myeloma cell lines, are characterized by a relatively low efficiency. It has been shown that expression of activated Ha- or N-ras oncogenes causes the malignant transformation and plasmacytoid differentiation of EBV-immortalized lymphoblastoid cell (LC) lines, suggesting that activated ras oncogenes can convert LC lines into effective hu-mAb producers. We have used retroviral vector-mediated gene transfer to introduce an activated Ha-ras (v-ras) oncogene into four distinct LC lines producing hu-mAbs of different classes (IgM and IgG) and specificities (to human insulin, human thyroglobulin and rabies virus glycoprotein). The cloning efficiency and antibody secretion of these ras-transformed LC (ras-LC) lines were compared with those of the hybrid LC (hyb-LC) lines generated by fusing the same parental LC lines with the Ig non-secretor F3B6 human-mouse hybrid cells. ras-LC lines were comparable to their hybrid counterparts in either parameter tested. This, together with the relatively higher efficiency of the method, suggests that ras transformation may constitute a valid alternative to the currently available technologies for hu-mAbs production from LC lines.

Thyroglobulin in medullary thyroid carcinoma: immunohistochemical study with polyclonal and monoclonal antibodies

The presence of thyroglobulin (TG) was investigated by immunohistochemistry with one polyclonal and three distinct monoclonal anti-TG antibodies in 19 primary and 15 metastatic medullary thyroid carcinoma (MTC) cases. In two primary tumors possessing a mixed trabecular and follicular growth pattern, a significant number of tumor cells were positive with the four antibodies in all parts of the tumor; these tumors were considered to be genuine mixed follicular and parafollicular tumors. The 17 other primary tumors looked like "classical" (ie, predominantly compact) MTC. Eight contained tubular or microfollicle-like structures that were consistently TG-negative. Eight contained residual entrapped normal follicles positive with the four anti-TG antibodies. In six cases isolated foci of tumor cells reacted with polyclonal antibody or monoclonal antibody 11. In 10 cases circulating TG stained positively with polyclonal antibody in vascular channels, five cases stained positively for TG with monoclonal antibody 11, four cases stained positively for TG with monoclonal antibody 7, and three cases stained positively for TG with monoclonal antibody 1. In metastases TG was found in tumor cells in only one instance, but positive reactions were obtained in vascular channels and macrophages in several cases. We conclude from this study that there is no genuine secretion of TG in classical, compact MTC, which differs morphologically and functionally from mixed follicular and parafollicular tumors secreting both TG and thyrocalcitonin.

Prevalence of thyroid autoantibodies in ambulatory elderly women

Major improvements in thyroid autoantibody testing have now become widely available. Seventy-five elderly ambulatory women from a senior citizens' center (mean age 74.5 yrs) were studied to reassess the prevalence of thyroid autoantibodies and to demonstrate how such tests related to clinical signs and symptoms of thyroid disease. We used the enzyme-linked immunoassay (ELISA) technique for the measurement of autoantibodies to thyroglobulin (hTg) and thyroid peroxidase (hTPO) (as microsomal antigen), since ELISA systems are economical, highly sensitive and specific for population screening. Autoantibodies to hTPO (hTPO-Ab) were present in 44% and hTg autoantibodies (hTg-Ab) in 32% of the study group. Ten women (13.3%) had elevated thyrotropin (TSH) levels. An elevated serum TSH was associated with the presence of hTPO-Ab in varying concentrations. The mean TSH value of 7.2 microIU/mL in those women with hTPO-Ab was significantly higher than the mean of 4.7 microIU/mL found in those women without thyroid autoantibodies (p < 0.01). However, additional testing for hTg-Ab was of little clinical value. These data indicate the high prevalence of thyroid autoimmune disease in the elderly female population. We conclude that screening for thyroid dysfunction is best achieved by the measurement of serum TSH in all women over the age of 60 years. The measurement of hTPO-Ab, but not hTg-Ab, was helpful in confirming the cause of thyroid failure in the elderly female population.

Control of human thyroid autoantibody production in SCID mice

In order to determine the phenotype of the cells required for thyroid autoantibody production, peripheral blood mononuclear cells (PBMC) from patients with autoimmune thyroid disease (AITD) were transferred to severe combined immunodeficient (SCID) mice. The production of human IgG, thyroglobulin (Tg) antibody and thyroid peroxidase (TPO) antibody in the SCID recipients was monitored for up to 4 months. PBMC from 10 of 13 AITD patients produced substantial IgG (> or = 100 micrograms/ml) and detectable Tg and TPO antibodies in recipient mice. PBMC pretreated to deplete or enrich T cells produced low or undetectable thyroid-specific antibody in SCID mice. Depletion of CD4+ T cells resulted in much lower or undetectable IgG, Tg and TPO antibodies compared with levels seen in recipients of control PBMC. By contrast, depletion of CD8+ T cells from the PBMC had no overall effect on autoantibody production, although with PBMC from some patients CD8+ depletion possibly enhanced both IgG and autoantibody production. In eight of 10 experiments, autoantibody levels reached maximal titres before total IgG levels peaked. It is considered that thyroid autoantibodies are produced from memory B cells activated in SCID mice and that this activation is T cell- and CD4+ T cell-dependent.

Study of induction of activation of human peripheral blood mononuclear cells with a non-activating form of anti-CD3 MoAb in autoimmune thyroid disease (AITD)

Anti-CD3 (OKT3) MoAb is a mitogenic agent which activates lymphocytes. We have studied the effects of murine anti-human OKT3 MoAb (IgG1) alone or in combination with IL-2, human thyroglobulin (Tg) and thyroperoxidase (TPO) antigens on the proliferation of whole peripheral blood mononuclear cells (PBMC) (including monocytes) or subtypes (T, CD4+, CD8+, B) as measured by tritiated thymidine (3H-TdR) incorporation. B cell differentiation was studied by measuring numbers of IgG-secreting cells and specific anti-TPO/anti-Tg-secreting cells by SPOT ELISA. PBMC or lymphocyte subtypes, obtained from 45 patients with Hashimoto's thyroiditis (HT), 40 Graves' disease (GD) and 51 normal controls were cultured in 96 microtitre plates for 6 days in the presence of OKT3 MoAb at final concentrations 25-250 ng/ml, IL-2 15 U/ml, Tg and TPO (1 micrograms/ml). Then cultures were pulsed with 0.2 microCi 3H-TdR/well and incorporation was measured after 18 h. IgG and anti-TPO/Tg-secreting cells were detected at 7 days. Higher proliferative responses from whole PBMC preparations in response to any of the combinations including OKT3 MoAb were observed in the HT preparations, while the basal values were the lowest. IL-2 alone increased these responses markedly, but equally in all groups. IL-2 in combination with OKT3 had an additive effect on proliferation, with higher responses in HT. Tg and TPO antigens did not change these responses. Most HT preparations responded with their maximum proliferation to the lowest concentration of OKT3 MoAb (25 ng/ml), whereas in GD and control preparations of PBMC these responses were shifted to higher concentrations (250 ng/ml); even with those, proliferation was not so enhanced in controls when compared with HT and GD preparations. In contrast, the proliferative responses of T cells alone and subpopulations of CD8+ suppressor/cytotoxic cells were decreased in HT preparations compared with controls. Monocytes were necessary for proliferation. In the subpopulation of B cells (> 95% pure) and CD4+ helper/inducer cells, differences did not reach significance. In spite of the effect on proliferation, OKT3 MoAb only mildly but significantly increased the numbers of IgG-secreting cells in HT and GD preparations and did not stimulate synthesis of specific antibodies. Our data suggest that the increased proliferative responses of whole PBMC to OKT3 MoAb in HT preparations might be due to insufficient activation of T suppressor/cytotoxic cells.

Antithyroid antibodies and the association with non-organ-specific antibodies in recurrent pregnancy loss

OBJECTIVES

The purpose of our study was to evaluate the incidence of antithyroid antibodies and non-organ-specific antibodies in women who have had three or more recurrent spontaneous abortions.

STUDY DESIGN

Sera from 45 women for the presence of antithyroid antibodies to thyroglobulin and thyroid peroxide and for the non-organ-specific autoantibodies to 6 phospholipids, 5 histones, and 4 polynucleotides were analyzed. Sera from 100 apparently health blood donors served as controls.

RESULTS

The test results of 14 (31%) of 45 study subjects were positive for one or both antithyroid antibodies compared with 19 (19%) of controls. Five (11%) of 45 patients had positive test results for one or more non-organ-specific antibodies, and 4 (8%) of 45 had positive test results for the lupus anticoagulant by either activated partial thromboplastin, tissue thromboplastin time, or both. Only 3 (21%) of 14 subjects whose test results were positive for thyroid antibodies also demonstrated non-organ-specific autoantibodies.

COMMENTS

The incidence of antithyroid antibodies in women who have had recurrent abortions appears not to be significantly increased compared with a normal random control population. Antithyroid antibodies do occur, however, with significantly greater frequencies in women with recurrent spontaneous abortions than non-organ-specific autoantibodies (p = 0.02). Organ-specific and non-organ-specific autoantibodies may serve as independent markers of risk for repeated pregnancy loss in patient populations where pregnancy loss is associated with abnormal autoimmune function.

Suppression of autoimmune thyroid disease by FK 506: influence on thyroid-infiltrating cells, adhesion molecule expression and anti-thyroglobulin antibody production

Autoimmune thyroid disease was induced in female PVG/c rats by neonatal thymectomy, followed by sublethal, whole body x-irradiation. Disease development, assessed by histological evidence of lymphocytic thyroiditis and circulating levels of anti-thyroglobulin antibodies, was reduced significantly by a 3-week course of FK 506 (0.5 or 1.5 mg/kg per day) commencing after the detection of autoantibody production. Thyroid-infiltrating mononuclear cells (MNC) in untreated rats stained predominantly for CD4+ and MHC class II antigen which was expressed widely on dendritic cells. Fewer infiltrating cells expressed TCR alpha/beta, CD5, CD8 or LFA-1 beta. Intercellular adhesion molecule-1 (ICAM-1) was observed on MNC, vascular endothelial cells and a minority of residual thyroid epithelial cells. FK 506 administration reduced markedly the incidence of infiltrating TCR alpha/beta +, CD5+, CD4+, CD8+, and LFA-1 beta + cells and the expression both of MHC class II antigens and ICAM-1 on MNC, endothelial cells and thyrocytes. Compared with normal PVG/c rats, there were reduced incidences of CD4+ CD8- and CD4- CD8+ lymphocytes and an elevation in the CD4+/CD8+ cell ratio in the spleens of animals with autoimmune thyroiditis. These changes were partially reversed by FK 506. Systemic drug levels estimated by enzyme immunosorbent assay were in excess of those known to blockade cytokine production by CD4+ T lymphocytes in vitro and some evidence of minor renal dysfunction was observed. The results are consistent with a therapeutic effect of FK 506 mediated via interference with CD4+ T lymphocyte function and adhesion molecule-dependent cytotoxic effector mechanisms.

Pitfalls in the use of ELISA to screen for monoclonal antibodies raised against small peptides

Small peptides are often conjugated to large carrier proteins such as thyroglobulin to increase their immunogenicity. Antibodies are raised against peptide, thyroglobulin and contaminants, such as immunoglobulins or BSA in the thyroglobulin preparation, but anti-contaminant antibodies will not be revealed if immune serum is diluted in buffer containing immunoglobulin-contaminated BSA. This may lead to the development of an inappropriate hybridoma-screening assay which detects more anti-contaminant than anti-peptide antibodies if ELISA plates are coated with a capture antibody or blocked with BSA. Dilution of culture supernatants in buffer containing BSA and Tween 20 minimises the risk of false positive results and makes plate-blocking unnecessary. The high affinity peptide-specific antibodies in immune serum, which are more readily detected than lower affinity monoclonal antibodies, may result in an inadequately sensitive hybridoma-screening ELISA.

Cross-reactive idiotypes on high affinity IgG class human monoclonal thyroglobulin autoantibodies

Anti-idiotypic antibodies have been developed in rabbits against three high affinity IgG class monoclonal human autoantibodies to thyroglobulin (Tg), which resemble polyclonal Tg antibodies in patients with autoimmune thyroid disease. Antibodies to 1E10 monoclonal anti-Tg (IgG2 kappa) recognised a cross-reactive idiotype (CRI) also present on 1D3 monoclonal anti-Tg (IG1 lambda) and on VB5 monoclonal anti-Tg (IgG2 lambda). The determinant to which anti-1E10 binds appears to involve, at least in part, the binding site for Tg. In contrast, anti-idiotypic antibodies raised against VB5 failed to bind to either 1E10 or 1D3, a finding consistent with previous studies on serum polyclonal Tg antibodies, which suggested that such antibodies exhibit a mixture of private and cross-reactive idiotypes. The observed sharing of idiotypic determinants was not related to subclass, light chain type or expression of a particular VH gene family in the heavy chain. Although binding of the anti-idiotypic antibodies to Tg antibodies in a panel of patients (including the donors of the lymphocytes used to produce the monoclonal antibodies) could not be detected, the monoclonal antibodies are representative of the donor patients' serum Tg antibodies, both in terms of IgG subclass and functional affinity. Thus these idiotypes may be present in patients' sera at levels below the detection limits of the assays employed. Cross-reactive regulatory idiotypes in mice often constitute a minor component of the anti-Tg repertoire. Consequently, it is possible that low levels of a CRI, such as the 1E10 CRI, may be involved in the regulation of the autoimmune response to Tg in man.

Immunization with thyroglobulin-specific cytotoxic T cell hybridoma induces anti-thyroglobulin antibodies: characteristics of monoclonal anti-thyroglobulin auto-antibody

We have produced five monoclonal autoantibodies (mA-Abs) to thyroglobulin (Tg) and more precisely to one epitope located within the < 10-kDa pTg tryptic fragment suspension capable of inducing experimental autoimmune thyroiditis (EAT). They were selected from spleen cells from CBA/J mouse immunized with the syngeneic cytotoxic T cell hybridoma HTC2. HTC2 cells are specific for one Tg epitope located within the EAT inducer pTg tryptic fragments and are able to prevent EAT induction by pTg. The restricted specificity of the humoral response previously observed in vivo was further demonstrated and defined in vitro at the single cell level. Competitive studies for binding to pTg or to the < 10-kDa pTg tryptic fragments demonstrated that HTC2-induced anti-Tg mA-Abs recognized an epitope(s) located in the < 10-kDa pTg tryptic fragment (as did 3B8G9, one conventional anti-Tg mA-Ab we selected). We ruled out the possibility that HTC2-induced anti-Tg A-Abs belong to the group of the natural A-Abs due to the lack of recognition of actin, dsDNA, TNP-ovalbumin, tubulin, their isotypes (IgG1 or Ig2a), and their affinities (in the 10(-7) M order of magnitude). The results strengthen the hypothesis that T and B cells sharing the same specificity can express similar idiotopes on their respective receptors for antigen. They also demonstrate the existence of a regulatory idiotypic network that could explain the protection from EAT after injection of inactivated HTC2 cells or its anti-clonotypic mAb.