Biomedical subjects

R Pujol-Borrell

Publications and source records attributed to R Pujol-Borrell.

At least 37 records · Page 2Linked to original sources

PubMed1997

Proteasome subunits, low-molecular-mass polypeptides 2 and 7 are hyperexpressed by target cells in autoimmune thyroid disease but not in insulin-dependent diabetes mellitus: implications for autoimmunity.

Autoimmune thyroid diseases (AITD) and insulin-dependent diabetes mellitus (IDDM) are two autoimmune syndromes of unknown etiology with common immune features. One is that the target cells, thyrocytes and pancreatic islet beta cells respectively, hyperexpress several proteins encoded in the HLA region: HLA class I, HLA class II and transporter associated with antigen processing (TAP-1): the clinical course and many aspects of the immunopathology are, however, quite different. Low-molecular-mass polypeptides 2 and 7 (LMP2 and LMP7) are proteasome subunits that increase the efficiency of endogenous antigen processing and are encoded in close vicinity to the TAP genes. We investigated whether LMP2 and LMP7 are hyperexpressed in thyrocytes and islet cells in AITD and IDDM. Thyroid tissue from Graves' disease patients (GD, n = 8) and Hashimoto thyroiditis (HT, n = 1) and pancreatic tissue from IDDM patients (n = 4) as well as control tissues were examined by the two-color indirect immunofluorescence technique. The results demonstrate that, in normal glands, thyrocytes and pancreatic islet cells express comparable moderate to low levels of LMP2 and LMP7. In AITD and IDDM, expression of LMP2/7 in the endocrine cells was disparate: while in AITD glands there was hyperexpression of LMP2 and 7 parallel to that of HLA class I and TAP-1, in the islet cells of recent onset diabetic pancreases (n = 2) the level of LMP2 and 7 expression was totally normal, including islets that were infiltrated by lymphocytes and hyperexpressed HLA class I and TAP-1. These observations suggest different mechanisms of endogenous peptides generation at the target cells in AITD from IDDM. Since this is a key step for the maintenance of peripheral tolerance, it may help to understand some of the different clinical features of the two autoimmune diseases.

Adolescent↗

PubMed1997

High prevalence of subclinical Sjögren's syndrome features in patients with autoimmune thyroid disease.

OBJECTIVE: To determine the prevalence of keratoconjunctivitis sicca and xerostomia related to Sjögren's syndrome (SS) in asymptomatic patients with diagnosed autoimmune thyroid diseases (AITD); and to investigate whether the immunopathologies of sialadenitis observed in AITD associated SS and primary SS are similar. METHODS: One hundred seventy-six patients diagnosed with AITD (88 with Graves' disease, 40 Hashimoto's thyroiditis, 48 primary myxedema) were tested for keratoconjunctivitis sicca (Schirmer's test and rose bengal staining) and for xerostomia (salivary scintigraphy and labial salivary gland biopsy). Immunohistopathological studies were performed on cryostat sections of bucal mucosa biopsies using antibodies to CD3, CD4, CD8, CD20, CD14, CD25, LFA-1, ICAM-3 HLA class II, tumor necrosis factor-alpha, interleukin 1, and interferon-gamma. RESULTS: Nineteen of 52 (37%) patients with AITD fulfilled the criteria for xerostomia and 39/170 (23%) for keratoconjunctivitis sicca. Features of SS were diagnosed in 43 of 176 (24%) patients with AITD, with similar prevalence in Graves' (20%). Hashimoto's thyroiditis (27%), and primary myxedema (29%). In AITD associated SS, infiltrating lymphocytes were mainly CD3+ T lymphocytes, with a CD4/CD8 ratio of 2:1. In most patients infiltrating lymphocytes expressed activation markers, HLA class II molecules, and interleukin 2 receptor (CD25). In some patients HLA class II was inappropriately expressed in the epithelial gland cells. CONCLUSION: The finding that a third of patients with AITD have SS features confirms that AITD and SS are mutually associated. Together with the similarity of immunopathology of sialadenitis in AITD associated SS in primary SS, this supports the theory that SS and AITD are 2 autoimmune diseases closely related pathogenetically.

Adolescent↗

PubMed1996

Advantages of using a cell separator and metrizamide gradients for human islet purification.

Human islet transplantation has a high rate of failure, often due to primary nonfunction, which suggests that islets are damaged during the processing of the pancreas. The preparation of human islets for transplantation is still a complex process that requires large teams of surgical and laboratory personnel. To overcome this problem, we have adopted the use of the IBM 2991 COBE cell separator and a metrizamide/Ficoll density medium that is easy to prepare. Twenty-seven pancreatic glands have been processed using the COBE cell separator, 23 of which were purified in metrizamide/Ficoll gradients and 4 in bovine serum albumin gradients. The results show an improvement of recovery and viability in these preparations when compared retrospectively with manual gradients. More importantly, the time required for purification was shortened to one fourth the usual time and total processing time is about half as long. Moreover, a team of two laboratory staff was regularly able to prepare islets for transplantation, reducing the separation time from 7 hr to 3.5 hr. We conclude that the automatic cell separator and metrizamide-based separation medium are useful modifications of current islet purification methods.

Adolescent↗

PubMed1996

Self-reactive cytotoxic gamma delta T lymphocytes in Graves' disease specifically recognize thyroid epithelial cells.

In this paper we report the isolation of a self-reactive cytotoxic gamma delta T cell line, 158RE.2, that originates from the T lymphocyte population infiltrating the thyroid gland of a patient with Graves' disease. Functional data using this cell line demonstrate that gamma delta T cells expanded in the thyroid tissue specifically recognize a ligand expressed by thyroid epithelial cells and cell lines of endocrine epithelial origin. The TCR expressed by these gamma delta T cells--V gamma I/V delta 5--is unusual in peripheral blood lymphocytes, and its specificity is clearly different from that observed in a high percentage of gamma delta T cells from PBL, which express the common TCR V gamma 9/V delta 2. The V gamma I/V delta 5 receptor is involved in the recognition of the ligand expressed by the thyroid cells, but not in the NK-like activity also displayed by 158RE.2. These cells express CD8 alpha alpha dimers, which participate in the thyroid ligand recognition but not in the NK-like activity. The epithelial cell recognition is not restricted by classical MHC class I or class II molecules, although the CD8 alpha alpha participation in the recognition suggests the involvement of nonclassical MHC molecules. These are the first data to be presented on self-reacting gamma delta T cells in human epithelium.

Animals↗

PubMed1996

Cloning of candidate autoantigen carboxypeptidase H from a human islet library: sequence identity with human brain CPH.

A number of proteins, many of them enzymes, i.e. glutamic acid decarboxylase (GAD), carboxypeptidase H, 37-40 K tyrosine phosphatase (ICA512, IA2/IA2 beta), have been proposed as islet autoantigens involved in the pathogenesis of IDDM. Until recently, progress in their characterization has been impeded by the inaccessibility of the human pancreas, resulting in many of them being cloned from animal or non-islet sources. Carboxypeptidase H, one of these enzymes, has been cloned and sequenced from human brain and from rat islets but not from human islets. In this study, we describe the production of a human islet cDNA library and the cloning of islet CPH from it. Since CPH clones were also detected in a human thyroid library, we have sequenced CPH from these two endocrine tissue libraries and compared them to the known brain sequence. The sequences from islets and thyroid were identical and differed from brain only in the absence of a second ATG in the predicted 5'non-coding region. Northern blot analysis revealed the presence of an identical 2.5 kb transcript in human islets, thyroid and brain. The confirmation of the existence of a single isoform of CPH expressed in brain and endocrine tissues simplifies future experiments to elucidate the role of CPH as autoantigen.

Animals↗

PubMed1996

Expression of transporter associated with antigen processing-1 in the endocrine cells of human pancreatic islets: effect of cytokines and evidence of hyperexpression in IDDM.

A possible role of transporter associated with antigen processing (TAP)-1 in the pathogenesis of IDDM has been investigated by examining the level of TAP-1 expression in the islets of IDDM pancreas and by studying in vitro the effect of interferon (IFN)-gamma, IFN-alpha, and tumor necrosis factor-alpha in TAP-1 expression by cultured islet cells. A remarkable hyperexpression of TAP-1 has been found in the endocrine cells (beta and non-beta) of IDDM islets, which constitutes first evidence of hyperexpression of this molecule in the target organ of an autoimmune disease. TAP-1 hyperexpression correlated clearly with HLA class I hyperexpression but only very partially with HLA class II ectopic expression. IFN-gamma and IFN-alpha, both cytokines putatively implicated in IDDM pathogenesis, were capable of inducing TAP-1 protein (as assessed by immunofluorescence flow cytometry) and message (by Northern blot analysis and reverse transcription polymerase chain reaction). These findings suggest that under the influence of cytokines (most probably IFN-alpha) beta-cells may express in their surface a high density of HLA class I-peptide complexes that may facilitate their recognition and lysis by low-affinity CD8+ T-cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1995

Hyperinducibility of HLA class II expression of thyroid follicular cells from Graves' disease. A primary defect?

Thyroid follicular cells (thyrocytes) from Graves' disease (GD) patients' thyroid glands express HLA class II molecules "ectopically." This phenomenon has been attributed to induction by locally produced cytokines and may be relevant to disease pathogenesis. We have compared IFN-gamma-mediated induction of HLA class II in thyrocytes from glands affected with GD and a nonautoimmune disease (MNG), to investigate a possible differential regulation of HLA expression between these two pathologies. HLA induction has been measured in primary thyrocyte cultures and control autologous macrophages stimulated or not stimulated with IFN-gamma. Comparison of flow cytometric data using an improved algorithm demonstrated that expression of HLA class II molecules is more readily induced in thyrocytes from GD than from MNG thyroid glands. This higher inducibility was parallel to a faster and stronger induction of HLA class II message in GD thyrocytes but did not correlate with the levels of HLA class II or class I originally expressed by thyrocytes in the tissue or with the degree of lymphocytic infiltration of the gland. There was no association with a particular HLA class II allele or with the presence of IFN-gamma and IL-2 in the tissue, as assessed by reverse transcription-PCR. No differences in the induction of class II were found in macrophages from each group of patients. These results suggest that an intrinsic feature of thyrocytes from GD patients is an up-regulation of HLA class II expression and that this is a characteristic that may facilitate the triggering of autoimmunity to "hyperinducible" thyroid glands.

Adolescent↗

PubMed1995

Interferon expression in the pancreases of patients with type I diabetes.

We have used a reverse transcriptase-polymerase chain reaction (RT-PCR) protocol to examine the expression of cytokines in the pancreases and islets of patients with type I diabetes. We detect a significant increase in the level of expression of interferon (IFN)-alpha in the pancreases of the diabetic patients as compared with the control pancreases. In contrast, IFN-beta was detected at comparable levels in both groups, while IFN-gamma was detected in three of four control pancreases and one of four pancreases from the diabetic individuals. The IFN-alpha cDNAs generated by the RT-PCR were cloned and sequenced to determine which alpha-subtypes were being expressed. We found that the repertoire of subtypes was quite limited in any one individual (diabetic or not), although each individual was different with respect to the pattern of subtypes expressed. We also examined these pancreases for the expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-2, IL-4, and IL-6. We found no detectable expression of TNF-alpha or IL-2 in any pancreases, and the expression of the other cytokines was variable, with no pattern emerging from the comparison of the diabetic and nondiabetic individuals. We conclude that, of the cytokines examined, only IFN-alpha was significantly increased in the diabetic patients, a result that is consistent with the possibility that this cytokine is directly involved in the development of type I diabetes.

Adolescent↗

PubMed1994

Growth inhibition of human endothelial cells by human recombinant tumor necrosis factor alpha and interferon-gamma.

We investigated the effect of recombinant tumor necrosis factor-alpha (rTNF-alpha) on the proliferative response of human umbilical vein endothelial cells (HUVEC) to normal human serum (NHS), in the absence or the presence of interferon (IFN)-gamma. rTNF-alpha significantly impaired NHS-stimulated HUVEC growth at a dose as low as 0.1 U/ml. The inhibitory effect of rTNF-alpha was dose-dependent up to 50-100 U/ml and was already evident after 2 h of incubation. Doses of rTNF-alpha in the range of 10 U/ml completely suppressed 3H-thymidine uptake stimulated by 7.5% NHS, and the effect was partially overcome by 10-20% NHS. rTNF-alpha was not cytotoxic at doses up to 1000 U/ml. rIFN-gamma was also effective in suppressing NHS-stimulated 3H-thymidine incorporation, and at low doses (0.1 U/ml) rIFN-gamma and rTFN-alpha showed an additive effect. The effect of TFN-alpha and IFN-gamma in antagonizing the proliferative response of vascular endothelium to the variety of growth factors contained in human serum could be relevant in a variety of pathologic conditions involving endothelium damage and proliferation.

Cell Division↗

PubMed1994

Pancreas in recent onset insulin-dependent diabetes mellitus. Changes in HLA, adhesion molecules and autoantigens, restricted T cell receptor V beta usage, and cytokine profile.

Insulin-dependent diabetes mellitus (IDDM), in which only the pancreatic beta cells are destroyed by the autoimmune response, is the paradigm of organ-specific autoimmunity. As a result of a combination of factors, the number of immunohistologic/cellular/molecular studies of pancreas in IDDM is very limited. We report here studies conducted in the pancreata of two IDDM patients: one newly diagnosed (case 1) and one long standing (case 2). In case 1, we demonstrated the presence of morphologically normal viable beta cells without evidence of viral infection. In both cases the expression of the autoantigens defined by islet cell Abs and by glutamic acid decarboxylase was markedly reduced in the islet cells whereas expression of hsp60, another putative autoantigen, was normal. Over-expression of HLA class I was detected in 58% of the islets in pancreatic sections and in cultured beta cells in case 1 and also in 30% of islets in case 2 but it was not restricted to any insular cell type. In case 1, there was "inappropriate" HLA class II expression in islets cells but it was a rare finding and not beta cell specific. The analysis of the correlation between class I overexpression, residual insulin, and insulitis suggests that the first event is the increase of HLA class I expression. Of adhesion molecules, ICAM-1, VLA, VCAM, and LFA-3 were normal and only ICAM-1 was moderately overexpressed in and around the islets of case 1 insulitis, as was detected by immunofluorescence which showed that 18% of the islets of case 1 had CD8+ lymphocytes as the predominant population. Reverse transcription-PCR demonstrated moderate V beta skewing and the profile of cytokines expected in CTLs: IL-2, IL-4, IL-10, and IFN-gamma negative, perforin positive. In addition, IFN-alpha, IFN-beta, and IL-6 transcripts were detected in the case 1 pancreas, consistent with the existence of a silent viral infection. Overall, the results indicated that, differently from spontaneous animal models of diabetes, in the pancreas of IDDM patients there are no elements of the inductive phase of the autoimmune response.

Acute Disease↗

PubMed1994

Characterization of neural cell adhesion molecule (NCAM) expression in thyroid follicular cells: induction by cytokines and over-expression in autoimmune glands.

NCAM (CD56) is a cell surface glycoprotein of the immunoglobulin superfamily expressed on neuroendocrine and natural killer (NK) cells which has considerable molecular heterogeneity due to differential splicing and post-translational modifications. NCAM has been detected in the thyroid follicular cells (thyrocytes) immunohistologically. We report here the molecular form, the modulation by cytokines and the levels of expression in thyroid pathology. By using a panel of MoAbs to NCAM on Western blots from thyrocyte extract we have determined that these cells express the 140- and 180-kD forms of NCAM. Exposure of primary cultures of thyrocytes to interferon-gamma (IFN-gamma), and even more, to the combination of IFN-gamma plus tumour necrosis factor-alpha (TNF-alpha) induced a clear increase in the expression of NCAM as assessed by FACS analysis. NCAM expression in thyrocytes was assessed by immunofluorescence in 59 surgical specimens of thyroid glands, and was found increased in 11/17 (64%) of Graves', in 5/25 (20%) of multinodular goitre (MNG) and in occasional adenoma glands. No correlation was found with the expression of HLA class I, class II or the degree of lymphocytic infiltration scored in adjacent sections, but it was often seen in areas infiltrated by macrophages. In conclusion, NCAM is an adhesion molecule whose expression is clearly increased in thyrocytes in autoimmune glands, probably as a consequence of exposure to cytokines locally released. Since one of the forms of NCAM expressed by thyrocytes has the capability to generate intracellular signal it may play a role in normal thyroid function. In addition, NCAM may facilitate the recognition of thyrocytes by lymphocytes, particularly by NK CD56+ lymphocytes.

Antibodies, Monoclonal↗

PubMed1993

Human pancreatic islet function at the onset of type 1 (insulin-dependent) diabetes mellitus.

Viable human pancreatic islets isolated from a recent-onset Type 1 (insulin-dependent) diabetic patient were used to perform in vitro studies. Pre-proinsulin mRNA and insulin content, as well as insulin response were analysed. Insulin response to glucose and forskolin was completely absent in diabetic islets, as compared to control islets. Insulin content was reduced to only one-third of control values (395.0 +/- 3.5 vs 989.0 +/- 46.3 microU/islet) and 20.7 +/- 3.9% of islets from the diabetic pancreas contained insulin-positive cells in immunofluorescence studies. Northern blot analysis revealed a severe reduction in the content of pre-proinsulin mRNA in diabetic pancreatic tissue. Our results indicate that although markedly decreased, beta cells in human pancreatic islets at the onset of Type 1 diabetes are still present. Nevertheless, pancreatic islet function is disproportionately impaired with a complete absence of an insulin response.

Adolescent↗

PubMed1993

Effects of a short prednisone regime at clinical onset of type 1 diabetes.

The effect of corticosteroids on beta cell function and humoral immune response in type 1 diabetes was tested in a 2-month trial conducted on 32 newly diagnosed patients (age 22.8 +/- 1.4 years, mean +/- S.E.M.). Prednisone was administered at immunosuppressive dosage (1 mg.kg-1.day-1) during the initial 10 days and at a maintenance dosage (0.3 mg.kg-1.day-1) for 50 days. Patients (n = 32) were enrolled within 6 weeks after diagnosis and matched in pairs for age, sex, presence of islet cell antibodies (ICA) and glucagon stimulated C-peptide levels. Insulin discontinuation was not contemplated. All the patients who received prednisone became ICA during treatment but in some (4 out of 10) this effect was only transient. Insulin antibodies (IA) were significantly lower in the prednisone group at second and third month (P < 0.05). No patient experienced complete remission but in 10 prednisone and 4 control patients the insulin requirements were below 0.3 IU/kg (P < 0.05). With similar glycemia the fasting C-peptide levels were higher in the treated patients. The profile of the insulin requirements during the follow-up was different in the two groups and at 9 months the prednisone group needed less insulin than the control (P < 0.05). Interestingly, within the prednisone-treated group and after 6 months, the levels of stimulated C-peptide improved significantly among the ICA+ patients while they were steady or declined in ICA- (P < 0.01). The analysis of variance covariance confirmed a positive interaction between ICA and the administration of prednisone on the outcome of beta cell function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Gamma delta lymphocytes in endocrine autoimmunity: evidence of expansion in Graves' disease but not in type 1 diabetes.

Endocrine autoimmune disorders are mediated by T cell-dependent responses to organ-specific antigens, but the mechanisms initiating the process remain unknown. Lymphocytes which use the gamma delta heterodimer as T cell receptor (TCR) for antigen constitute a distinct subset of T cells whose function remains elusive. In order to investigate their possible involvement in endocrine autoimmunity we have determined the proportion of gamma delta T cells in the peripheral blood of 23 patients with type 1 (insulin-dependent) diabetes mellitus (type-1 DM) and 30 patients with autoimmune thyrotoxicosis (Graves' disease). T lymphocyte TCR expression was assessed by fluorescence-activated flow cytometry on peripheral blood mononuclear cells using MoAbs UCHT1 (CD3), TCR delta 1 (gamma delta TCR), WT31 and beta F1 (alpha beta TCR) and both the percentage of T cells expressing gamma delta and the ratio gamma delta/alpha beta were calculated. In the diabetic patients gamma delta cells were not significantly different from the control group (7.7 +/- 54% versus 8.0 +/- 5.5% of T cells, P NS). There was no relation between the proportion of gamma delta lymphocytes and the presence of islet cell antibodies (ICA) in the sera. The Graves' patients showed a tendency towards a higher proportion of gamma delta T lymphocytes than the controls (gamma delta/alpha beta ratios: 0.095 +/- 0.047 versus 0.063 +/- 0.022, P = 0.03). In 14 Graves' patients the number of gamma delta were measured in paired samples of peripheral and intrathyroidal lymphocytes, demonstrating an expansion of gamma delta within the thyroid glands (0.21 +/- 0.3 versus 0.095 +/- 0.047, P = 0.032). Immunohistochemical studies showed that gamma delta cells were scattered among the predominant alpha beta lymphocytes infiltrating the thyroid gland and that they account for 10% of intraepithelial lymphocytes. No relation was found between the increase of gamma delta lymphocytes and any clinical features.

Adolescent↗

PubMed1993

Expression of glutamic acid decarboxylase (GAD) in the alpha, beta and delta cells of normal and diabetic pancreas: implications for the pathogenesis of type I diabetes.

One of the paradoxes of insulin-dependent diabetes mellitus is that the destruction of the pancreatic islets' endocrine cells is restricted to the insulin-producing beta cells, whereas the main autoantibodies, islet cell antibodies (ICA), are directed against all endocrine islet cells. GAD has recently been proposed as the main target of the humoral and cellular autoimmune attack to the islets, and since in rat pancreas this enzyme was expressed only in the beta cells, this provided an explanation for the cell specificity of the destructive process. The finding of GAD-positive cells in the islets of two diabetic patients, one of whom had completely lost the beta cells, led us to study in detail the distribution of GAD in normal human islet cells using a panel of GAD antisera and the double indirect immunofluorescence technique on cryostat sections, monolayer cultures and cytosmears. The results showed that GAD is present not only in the cytoplasm of beta cells but also in 69% of the alpha and 27% of the delta cells. GAD was not present, however, on the surface of the islet cells. These results suggest that the cellular distribution of GAD can not by itself explain the selectivity of beta cell destruction in insulin-dependent diabetes mellitus.

Adult↗

PubMed1992

Expression of intercellular adhesion molecule-1 in thyroid follicular cells in autoimmune, non-autoimmune and neoplastic diseases of the thyroid gland: discordance with HLA.

The presence of intercellular adhesion molecule-1 (ICAM-1) on epithelial cells facilitates their recognition by specific T lymphocytes. To assess the possible role of ICAM-1 in the recognition of thyroid follicular cells by T cells in thyroid autoimmune disease, we investigated the expression of ICAM-1 in thyrocytes from thyroid glands affected by Graves' disease, in glands with non-autoimmune pathology and normal glands using immunofluorescence staining on cryostat sections and on dispersed cell preparations. Sequential tissue sections from glands affected by Graves' disease (n = 15), multinodular goitre (MNG, n = 26), benign nodules (n = 11), primary carcinomas (n = 12) and control thyroid glands (n = 5) were stained for ICAM-1, HLA class I, HLA class II, CD3 and thyroid peroxidase (TPO). Weak and patchy ICAM-1 expression was found in the thyrocytes of 4/15 (27%) Graves' disease and of 1/26 (4%) multinodular goitre glands. In contrast, ICAM-1 expression was detected in the thyrocytes of 5/11 (45%) benign nodules and of 8/12 (67%) thyroid carcinomas in which it was sometimes strong. Thyrocytes in the five control glands were negative. These results correlated well with flow cytometry data from 23 of these glands which showed that ICAM-1 expression in thyrocytes from Graves' patients was, when present, 'dull', while in some malignant thyrocytes it was 'bright'. In preparations of thyrocytes from Graves' disease glands we found a striking discordance between the high levels of expression of HLA class I and HLA class II and the low expression of ICAM-1. This is surprising since in vitro the expression of these three molecules is equally induced by IFN-gamma and TNF-alpha. These results suggest that additional factors are involved in the induction of the inappropriate HLA class II expression observed in the thyrocytes of glands affected by Graves' disease.

Antigens, CD↗

PubMed1992

Induction of intercellular adhesion molecule-1 but not of lymphocyte function-associated antigen-3 in thyroid follicular cells.

We investigated the expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-3 (LFA-3) by thyrocytes and their regulation by cytokines. Immunofluorescence studies on cryostat sections and on freshly dispersed cell preparations showed that ICAM-1 and LFA-3 are barely detectable in non-autoimmune thyrocytes. However, thyrocytes acquired ICAM-1 expression in culture. IFN-gamma, IL-1 beta and TNF-alpha produced a clear enhancement of ICAM-1 expression. When tested in combination, IL-1 beta and TNF-alpha were additive to the IFN-gamma effect. LFA-3 expression was not modulated by these cytokines. In the HT93 thyroid cell line generated by transfection with SV40, ICAM-1 and LFA-3 were both constitutively expressed at high levels. Cytokines modulated ICAM-1 expression similarly, but to a greater extent than in normal thyrocytes. LFA-3 remained unmodified. These results support the notion that normal thyrocytes are immunologically silent cells. The capability of cytokines to induce ICAM-1 together with HLA class I and class II-expression on thyrocytes suggests that under their influence, these cells may express all the surface molecules required for antigen presentation and/or for being recognized as target cells in the context of thyroid autoimmune disease.

Antibodies, Monoclonal↗

PubMed1992

Reevaluation of autoantibodies to islet cell membrane in IDDM. Failure to detect islet cell surface antibodies using human islet cells as substrate.

Since their demonstration in 1975, ICSAs have been proposed as serological markers and pathogenic elements in IDDM. ICSAs are detected in the sera of most newly diagnosed IDDM patients by indirect IFL that uses viable preparations of rat islet or insulinoma cells as substrate, but they also can be detected by using human insulinoma or fetal islet cells. We have tried to demonstrate ICSAs in the sera of 31 newly diagnosed diabetic patients, including 6 positive samples on human fetal islet cells, which used their natural target for the first time: normal human islet cells. In spite of using different types of preparations of these cells (i.e., freshly dispersed cell suspensions, monolayer cultures, or dispersed islets after culture), ICSAs could not be detected by IFL under the UV microscope, nor by flow cytometry. In contrast, 9 of 29 of the sera gave a positive staining on the RIN rat insulinoma cells. In an attempt to establish whether the putative ICSA autoantigen is present in the surface of human islet cells in the diabetic pancreas, the insulitis microenvironment was emulated by exposing the islets to three types of stress: 1) cytokines (IFN-gamma and TNF-alpha); 2) heat shock; and 3) hyperglycemia. However, diabetic sera failed again to recognize membrane antigens on the islet cells after either of these treatments. Neither were islet cells from a newly diagnosed diabetic patient stained by its autologous serum (ICA titer > 80 JDF U). These results suggest that ICSA autoantigen is not expressed in the membrane of human islet cells and therefore raises doubts about their proposed pathogenic role.

Adolescent↗