Antibody to intermediate filaments of the cytoskeleton

Relationship between Smooth Muscle and Cytoskeleton Antibodies in Neuroblastoma

The previously reported high prevalence of smooth muscle antibodies in neuroblastoma has been found to be associated with a similarly elevated prevalence of anti-cytoskeleton antibodies. The most relevant finding is related to anti-microfilaments (anti-actin) and anti-microtubules antibodies, which were detected with highly significantly different prevalences when compared with a disease control group (p < 0.001 and p < 0.000001, respectively). The correspondence between smooth muscle antibodies and anti-cytoskeleton antibodies is incomplete, and it is more relevant for anti-microfilaments. It is concluded that antigen specificities of smooth muscle antibodies in neuroblastoma are as complex as documented in other diseases. Possible pathogenetic and clinical implications emerging from these data are discussed.

The immunohistochemical distribution of vimentin in human temporomandibular joint samples

The aim of this investigation was to evaluate the immunohistochemical distribution of vimentin in the temporomandibular joint (TMJ) and to compare it with the control specimens. Immunohistochemical distribution in the disc and synovial membrane in 30 human TMJ (internal derangement of TMJ, n = 20; and control, n = 10) was studied immunohistologically using paraffin-embedded tissue and specific anti-human vimentin monoclonal antibody. Vimentin expression was distributed in chondrocyte-like cells, synovial cells and endothelial cells. There was an obvious distinction of vimentin immunoreactivity between the control specimens and internal derangement cases, in the posterior and/or anterior loose connective tissues. In particular, intensive vimentin expression was detected in the hypertrophic synovial membrane of internal derangement cases. The findings of the present study suggest that vimentin might be an important marker of pathological hypertrophy of the synovial membrane and/or connective tissue with internal derangement of TMJ.

In the rheumatoid pannus, anti-filaggrin autoantibodies are produced by local plasma cells and constitute a higher proportion of IgG than in synovial fluid and serum

IgG anti-filaggrin autoantibodies (AFA) are the most specific serological markers of rheumatoid arthritis (RA). They include the so-called 'anti-keratin antibodies' (AKA) and anti-perinuclear factor (APF), and recognize human epidermal filaggrin and other (pro)filaggrin-related proteins of various epithelial tissues. In this study we demonstrate that AFA are produced in rheumatoid synovial joints. In 31 RA patients, AFA levels were assayed at equal IgG concentrations in paired synovial fluids (SF) and sera. AFA titre-like values determined by indirect immunofluorescence and immunoblotting and AFA concentrations determined by ELISA were non-significantly different in serum and SF, clearly indicating that AFA are not concentrated in SF. In contrast, we demonstrated that AFA are enriched in RA synovial membranes, since the ELISA-determined AFA in low ionic-strength extracts of synovial tissue from four RA patients represented a 7.5-fold higher proportion of total IgG than in paired sera. When small synovial tissue explants from RA patients were cultured for a period of 5 weeks, the profile of IgG and AFA released in the culture supernatants was first consistent with passive diffusion of the tissue-infiltrating IgG (including AFA) over the first day of culture, then with a de novo synthesis of IgG and AFA. Therefore, AFA-secreting plasma cells are present in the synovial tissue of RA patients and AFA can represent a significant proportion of the IgG secreted within the rheumatoid pannus.

[Study on surgical treatment for lung cancer associated with giant bullous disease]

Five patients of primary lung cancer with giant bullous disease underwent surgery from April 1985 to December 1995. All patients were male and heavy smokers, and the median age was 50 years. The location of the tumor was in the right upper lobe in four patients and in the left upper lobe in the other. Three patients were treated by lobectomy and two by sleeve lobectomy. Histological examination showed large cell carcinoma in four patients and poorly-differentiated adenocarcinoma in the other. The pathological stage was I in three. IIIA in one, and IV in the other. Two of three in stage I have survived for more than 6 years postopertively without recurrence, and the other died of brain metastasis. The stage IIIA case and the IV case died 3 years and one year postoperatively, respectively. The clinical features of lung cancer associated with giant bullous disease was discussed by reviewing 33 patients reported in Japan, including our patients. In 13 patients, lung cancer and bullous disease were diagnosed simultaneously (group A), and in 20 patients, bullous disease were diagnosed prior to the appearance of an abnormal shadow due to lung cancer (group B). The patients in group B had a tendency to be diagnosed at an earlier stage of lung cancer than the patients in group A. In the patients of stage I, the 5-year survival rate was 78.6%, however, in the patients of more than stage IIIA, 3-year survival rate was 26.5% and the 5-year survival rate was 0%. Significant differences in the survival curves were demonstrated between the cases with stage I and the cases with more than stage IIIA. In conclusion, in order to improve the prognosis of lung cancer with giant bullous disease, it is considered to be important to detect giant bulla prior to lung cancer, and when a case of bullous disease is found, periodical follow-up must be done to find early stage lung cancer.

Antiperinuclear factor: a useful test for the diagnosis of rheumatoid arthritis

The objective of this study was to determine: (1) the diagnostic value of antiperinuclear factor (APF), (2) the types of immunoglobulins involved in the reaction and (3) the presence of the antibody in paired samples of serum and synovial fluid (SF). We studied 408 serum samples from the following: healthy controls (n = 68), patients with rheumatoid arthritis RA; n = 160, 106 RF-positive and 54 RF-negative and patients with other rheumatic diseases (n = 180). We examined paired serum and SF samples in 27 patients (8 with RA and 19 with other rheumatic conditions). APF was determined by an indirect immunofluorescence assay. A group of 30 APF-positive serum samples was incubated with fluorescent-labelled antisera against IgG, IgM and IgA independently. APF was positive in 55.7% of patients with RF-positive RA, in 35.2% of patients with RF-negative RA, in 11.1% of patients with other rheumatic diseases and in 5.9% of healthy controls. Statistical differences were found between RF-positive RA and the other three groups (P = 0.02, P = 0.0001, P = 0.0001, respectively) and between RF-negative RA and the groups of other rheumatic diseases (P = 0.0001) and healthy controls (P = 0.005). The specificity of the test for RA was 90.2%. APF was present in three SF samples from RA patients (37.5%). The reaction was mediated by immunoglobulins of the IgG class in 100% of those tested, and, in addition, 30% were of IgA and 6.7% of IgM classes. We concluded that APF is a good diagnostic test that could be included in the classification criteria of RA, it can be present in SF and it is predominantly an antibody of the IgG class.

Characterisation of anticytoplasmic antibodies and their clinical associations

OBJECTIVES

To characterise the cytoplasmic staining patterns identified by indirect immunofluorescence (IF) of human epithelial (HEp-2) cells and the antigens recognised using additional serological techniques. To define the disease associations of anticytoplasmic antibodies.

METHODS

Sera from 1173 patients were screened for cytoplasmic IF staining on HEp-2 cells and the patterns characterised. The presence of antimitochondrial antibodies (AMA) was evaluated by a sensitive anti-pyruvate dehydrogenase complex enzyme linked immunosorbent assay (ELISA) (IgG) and by immunoblotting. Detection of antibodies to extractable nuclear antigens (ENA) was performed by double immunodiffusion and the presence of anti-ribosomal P antibodies was determined by immunoblotting.

RESULTS

Cytoplasmic IF staining was demonstrated in 75 sera (6.4%). Six different patterns were recognised: coarse granular filamentous speckles (AMA, n = 9); condensed large speckles (anti-golgi apparatus antibodies, n = 3); cytoskeletal (n = 9); centriolar (n = 4); diffuse coarse speckles (n = 33); and fine speckles (n = 17). Of the nine sera with an AMA pattern, the presence of these antibodies was confirmed in seven by the ELISA (n = 6) and on immunoblotting (n = 7). One of the seven patients had primary biliary cirrhosis, and two had scleroderma. Two patients with anti-golgi antibodies had rheumatoid arthritis and two with anticentriolar antibodies had scleroderma. Of 33 sera that had cytoplasmic staining and were ANA negative, three were positive for anti-Ro and two were positive for anti-Jo-1 antibodies.

CONCLUSIONS

In general, defined cytoplasmic IF patterns have no specific disease associations. However, the finding of cytoplasmic fluorescence should not be ignored, as it may indicate the presence of antibodies to ENA in the absence of nuclear staining.

Immunoblotting detection of so-called 'antikeratin antibodies': a new assay for the diagnosis of rheumatoid arthritis

OBJECTIVES

To assess the diagnostic value for rheumatoid arthritis (RA), of an immunoblotting assay based on the rat oesophagus epithelium antigens recognised by the so-called 'antikeratin antibodies' ('AKA'), antigens that have been identified as three non-cytokeratin proteins (referred to as A, B and C proteins).

METHODS

After polyacrylamide gel electrophoresis in non-denaturing conditions and electrotransfer of an epithelial extract, the immunoreactivities to the A, B and C proteins of a series of serum samples from 88 patients with RA and 100 patients with non-rheumatoid rheumatic diseases, were semiquantitatively evaluated.

RESULTS

A total of 81.8% of RA serum samples recognised the three proteins, while 91% of non-RA serum samples only weakly recognised the A and B proteins but not the C protein. Only in the group of RA patients, were the titres of the antibodies to the A, B and C proteins found to be significantly correlated with each other and with the titres of 'AKA' detected by the standard indirect immunofluorescence (IIF) method. For a diagnostic specificity of 99%, the diagnostic sensitivities of the detection of the A and B proteins were 50% and 43.2%, respectively, when those of the detection of 'AKA' by IIF and of IgM-rheumatoid factor by enzyme-linked immunosorbent assay were 42% and 54%, respectively. In contrast, at a same specificity of 99%, the diagnostic sensitivity of the detection of the C protein was significantly higher with a value of 70.5%.

CONCLUSION

This immunoblotting assay which is the first immunochemical method proposed for the detection of 'AKA, should be validated on larger series of patients but can already be considered as a very powerful test for the serological diagnosis of RA.

Sustained and distinctive patterns of gene activation in synovial fibroblasts and whole synovial tissue obtained from inflammatory synovitis

Fibroblastoid synovial lining cells isolated from rheumatoid and other chronic inflammatory synovial tissue exhibit distinctive and sustained alterations in serial culture not commonly found in similarly cultured cells from osteoarthritic synovium. These are demonstrable using a multi-gene dot blot assay by labelling reverse transcribed fibroblast cDNA which is hybridized to plasmids containing relevant target gene inserts. Cultured synovial fibroblastoid cells from patients with chronic inflammatory synovitis expressed significantly higher levels of stromelysin, vimentin and TIMP-1 mRNA and lower levels of c-myc compared to cells isolated from osteoarthritis synovium although with considerable variation. Early fetal synovial lining cells were similar to cells from osteoarthritis synovium but vimentin expression was higher. Marked differences in patterns of gene expression between cell lines persisted through 10 serial passages over 6-8 months. In whole synovia, the average level of mRNA for stromelysin, vimentin, IL-4, IL-6, TIMP-1, cathepsin D, gelatinase, TGF alpha, c-fms and DR beta were preferentially expressed in inflammatory tissue while c-myc expression was higher in osteoarthritis synovium. Inflammatory synovium also expressed TNF alpha, IL-1 alpha, IL-1 beta, IL-2, c-sis, tissue plasminogen activator, CSF-1, and GM-CSF. This pattern resembles, in part, that found in cultured inflammatory fibroblasts but, in addition, gene products apparently reflecting the presence of activated monocytes and lymphocytes were detected. These results provide evidence that profiles of certain gene activation in cells from patients with inflammatory synovitis differ from those with non-inflammatory disease and suggest that the fibroblastoid cells are responsible for a considerable proportion of the altered phenotypic expression pattern in whole tissue. Furthermore, this modulated pattern of gene activation appears to be an intrinsic pro-inflammatory characteristic of the fibroblastoid cells initiated in response to chronic inflammation and persists for a prolonged period in the absence of other inflammatory cells.

Differential B lymphocyte galactosyltransferase activity in the MRL mouse model of rheumatoid arthritis

Oligosaccharides can be of fundamental importance to glycoprotein function. Glycosylation abnormalities are present in rheumatoid arthritis (RA) and may be associated with disease pathogenesis. To determine whether similar disease mechanisms occur in the MRL-1pr/1pr autoimmune arthritic mouse, studies on B lymphocyte galactosyltransferase (GTase) have been carried out. In MRL mice, a significant reduction in peripheral blood lymphocyte (PBL) GTase activity was found when compared to their paired splenic (SP) GTase activity (-69%, p = 0.002) and histocompatible non-autoimmune control CBA/Ca mice (-67%; p = 0.002). The changes in PBL GTase activity are similar to those found in RA and on further analysis, using mixing experiments in the presence of purified human milk GTase, this reduction was shown not to be due to the presence of a soluble intracellular GTase inhibitor. Furthermore when examining MRL derived hybridoma cells producing IgG, significantly reduced GTase activity was detected in the rheumatoid factor (RF) producing hybridoma cells compared to those secreting an irrelevant antibody (-21%, p < 0.05). Together these findings suggest that the glycosylation changes observed in this study, and those reported previously in RA, are tissue-specific, may result from cells trafficking from centres of disease activity and are not the result of direct enzyme inhibition. It is now important to further understand the mechanisms controlling glycosylation and relate disease associated changes with those occurring as part of normal cellular physiology.

Antibodies to T- and L-isoforms of the cytoskeletal protein, fimbrin, in patients with systemic lupus erythematosus

The cytoskeleton is a complex network of proteins that maintain cell shape, mobility, and organelle function. Its components can be divided into three distinct classes: microfilaments, microtubules, and intermediate filaments. Fimbrins are microfilament proteins, a family of cytoplasmic phosphoproteins. Expression of the L-fimbrin isoform is restricted to replicating blood cells and expression of the T-fimbrin isoform to replicating cells of solid tissues. Sera from normals and from patients with systemic lupus erythematosus (SLE), juvenile arthritis, rheumatoid arthritis, Sjögren's syndrome, osteoarthritis, vasculitis, scleroderma, and mixed connective tissue disease were tested for the presence of antibodies to T- and L-fimbrin by ELISA, using purified recombinant fimbrin. The mean OD of sera from SLE patients was significantly higher than in normals (T-fimbrin, P less than 0.0001; L-fimbrin, P less than 0.001). 48 of 98 SLE sera had antibodies to T-fimbrin; 32 had antibodies to L-fimbrin; 20 had antibodies to both; 28 had only anti-T, and 12 had only anti-L-fimbrin. The mean OD for sera of the other rheumatic diseases was not significantly different from normals. The presence of either L- or T-fimbrin antibody was associated with pleuropericarditis (P = 0.015), photosensitivity (P = 0.011), and anti-Sm antibody (P = 0.010). Central nervous system SLE was associated with the presence of the L-fimbrin antibody alone (P = 0.016). There was a strong association between DR7 (but not other MHC alleles) and anti-L-fimbrin antibodies in SLE patients (chi square = 18; P less than 0.00002). No MHC association was observed with anti-T-fimbrin antibodies.

Fine structure of the human synovial lining cell in osteoarthritis: its prominent cytoskeleton

The cytoskeleton of the human osteoarthritic synovial lining cell (SLC) consists of an extensive number of vimentin intermediate filaments (IFs) in addition to microfilaments and microtubules. The IFs are especially prevalent in the SLC processes, but are commonly seen in a paranuclear arrangement. Processes, ending in numerous microvilli and blebs, project into the joint space. Scanning electron microscopy (SEM) further reveals the processes that may parallel the synovium surface for a short distance. IFs extend to the termination of such Numerous pinocytotic vesicles and extensive rough endoplasmic reticulum (rER) are characteristic of the type B cells. Lysosomes and long microvilli identify the type A cell. Punctate adherens, gap junctions, and cilia are the cell membrane specializations of the osteoarthritis (OA) synovium. A comparison with synovium from rheumatoid arthritis (RA) patients is made in order to assess the effect o this inflammatory disease on the SLC cytoskeleton, cell type relationship, and cell arrangement. The prominent cytoskeleton appears to play an important role in the architecture of the synovium. Our findings are further presented in the form of a drawing which in some aspects could describe the morphology of the normal synovium.

Antiperinuclear factor, a marker autoantibody for rheumatoid arthritis: colocalisation of the perinuclear factor and profilaggrin

The antiperinuclear factor, an autoantibody specific for rheumatoid arthritis, was found in 51/63 (81%) patients with rheumatoid arthritis by indirect immunofluorescence on human buccal mucosa cells. The sensitivity of the antiperinuclear factor test was increased by pretreating the buccal mucosa cells with 0.5% Triton-X100. The specificity of the test for rheumatoid arthritis as compared with control serum samples was maintained. The localisation of the perinuclear factor in the keratohyalin granules of the buccal mucosa cells was verified by immunoelectron microscopy. The perinuclear factor was found to be an insoluble protein whose antigenicity was sensitive to various fixation procedures. In serum samples from patients with rheumatoid arthritis there was a positive correlation between the presence of antiperinuclear factor and the presence of the so called antikeratin antibodies as detected by immunofluorescence on unfixed rat oesophagus cryostat sections. No relation was found between the presence of the perinuclear factor and either the rheumatoid factor, Epstein-Barr virus components, or any cytokeratin. By double immunofluorescence an exact colocalisation of the perinuclear factor and profilaggrin was found. Although the precise biochemical identity of the perinuclear factor remains unclear, our results suggest that it is a protein only present in the fully differentiated squamous epithelial cell layer.

Natural IgG to epidermal cytokeratins vs IgG to the stratum corneum of the rat oesophagus epithelium, so-called 'antikeratin antibodies', in rheumatoid arthritis and other rheumatic diseases

In order to study the relationships between the circulating IgG autoantibodies to epidermal cytokeratins (AECK), which were described in normal human sera as well as in sera from patients with various diseases, and the so-called 'antikeratin' IgG antibodies ('AKA'), which are highly specific for rheumatoid arthritis (RA), we simultaneously investigated AECK by a specific ELISA using cytokeratins from human stratum corneum (SC) and 'AKA' by semiquantitative indirect immunofluorescence assay on rat oesophagus epithelium, in a large series of 595 rheumatic sera including 229 RA. AECK were found to be present in all the 595 sera, with large inter-individual variations in titre. Whatever the titre chosen as threshold, the autoantibodies (auto-Ab) were never found to be specific for any rheumatic disease. Moreover, in RA, they were found to vary independently of IgM rheumatoid factor (IgM-RF), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), while they were found to vary in parallel with the total serum IgG concentration. In contrast, although 568 of the 595 rheumatic sera contained antibodies that labelled the rat oesophagus SC, the highest titre-like values were obtained with RA sera. At a convenient threshold, 95 (41.5%) of the 229 RA were detected while only three false positives (0.08%) remained among the 366 non-RA sera. Moreover, in RA, 'AKA' were found to be related to IgM-RF, ESR and CRP, while their titre was found to be independent of the total serum IgG concentration. Lastly, no statistical correlation was found between the antibodies, either in the whole sample of 595 sera or in any diagnostic group. In conclusion, the simultaneous investigation of AECK and 'AKA' showed that they differ from each other in all the aspects explored. AECK belong to the widely explored family of natural auto-Ab against cytoskeleton components and do not constitute a diagnostic marker while, on the other hand, 'AKA' confirmed their high diagnostic specificity for RA. It can also be asserted that, in spite of their name, 'AKA' do not recognize human epidermal cytokeratins, at least in the denatured form they present in ELISA. Therefore, they recognize either conformational epitope(s) appearing on cytokeratins during the late stages of the cornification process, or epitope(s) borne by rat cytokeratins but absent on human cytokeratins, or lastly a non-cytokeratin SC antigen.

Healthy individuals and patients with systemic lupus erythematosus have unique, person-specific spectra of antibodies detectable on immunoblots

Through the technique of immunoblotting, the spectrum and organ specificity of antibodies in healthy individuals and patients with systemic lupus erythematosus were examined. It was demonstrated that healthy individuals and patients with autoimmune disease have antibodies, some tissue specific and some not tissue specific, which are present in a pattern that is unique to each individual.

Antibodies to cytoskeletal proteins in patients with Crohn's disease

The immunologic basis of inflammatory bowel disease has been the focus of interest of a series of studies on Crohn's disease and the process of immune sensitization at the gastrointestinal mucosal level is functionally poorly understood. To date only few contradictory reports concerning the incidence of autoantibodies in patients with this disease exist. The aim of this study was to investigate the sera drawn from 60 patients suffering from biopsy-proven Crohn's disease to evaluate the prevalence of autoantibodies against nuclear antigens and cytoskeletal proteins. Using standard methods, no anti-nuclear antibodies or antibodies to extractable nuclear antigens could be detected. All sera were also negative for antibodies to double-stranded DNA, anti-mitochondrial antibodies, and antibodies to gastric parietal cells. Using sensitive enzyme-linke immunosorbent assays with purified antigens and Western blotting with cytoskeletal proteins of human intestinal cells, the following antibodies could be demonstrated: cytokeratin 18 autoantibodies (IgG 20.0%; IgM 6.7%; IgA 13.3%), actin antibodies (IgG 36.7%; IgM 48.3%, IgA 26.7%), desmin antibodies (IgG 6.7%; IgM 15.08%; IgA 5.0%), vimentin antibodies (IgG 3.3%; IgM 16.7%; IgA 10.0%) and tropomyosin antibodies (IgG 3.3%; IgM 3.3%, IgA 5.0%). Statistically significant correlations could be found for levels of cytokeratin 18 antibodies (IgM-type) and the BEST index of activity, and for levels of desmin antibodies (IgM-type) and the van HEES index of activity. Highest levels could be measured for actin antibodies (IgG-type) in patients with isolated disease manifestation in the colon. The mechanism of induction of autoantibodies against cytoskeletal components in Crohn's disease still remains obscure. Unmasking of hidden antigens after cell injury during the inflammatory process of disease might lead to sensitization and antibody production. The pattern of antibodies in patients with Crohn's disease seems to be different compared with that of connective tissue diseases.

High diagnostic value in rheumatoid arthritis of antibodies to the stratum corneum of rat oesophagus epithelium, so-called 'antikeratin antibodies'

Serum antibodies to the stratum corneum of rat oesophagus epithelium, so-called 'antikeratin antibodies', have been largely demonstrated in rheumatoid arthritis (RA). IgM and IgG antibodies to this epithelium were studied by semiquantitative immunofluorescence in 528 patients with perfectly characterised rheumatic diseases, including 178 with classical or definite RA. Histological analysis of IgG antibodies showed that only antibodies which produce a linear laminated pattern restricted to the stratum corneum (IgG antikeratin antibodies) are highly specific for RA; all the other labelling patterns are not disease specific. By a semiquantitative evaluation of the stratum corneum fluorescence intensity it was shown that the diagnostic value of IgG antikeratin antibodies closely depends on their titre and it was established in objective conditions that the sensitivity is 43.26% when the specificity reaches 99.14%. A high titre of IgG antikeratin antibodies was actually pathognomonic for RA. Both the histological and semi-quantitative analyses showed that IgM antibodies to rat oesophagus epithelium, though frequently detected, are of no diagnostic value, either for RA or for any other rheumatic disease that was studied. From a review of all the international reports on IgG antikeratin antibodies it was found that, to date, 4080 patients, including 1694 with RA, have been assayed for antikeratin antibodies by 11 different research groups. Analysis of all the results obtained under comparable technical conditions showed that IgG antikeratin antibodies constitute the most specific serological criterion for the diagnosis of RA. Furthermore, it was found that their incidence does not depend on disease duration: they are present in one third of rheumatoid factor negative patients with RA, and they seem to be related to disease severity or activity, or both. Their detection in the diagnosis of rheumatic diseases should become systematic.

Antibodies to hnRNP core protein A1 in connective tissue diseases

We investigated the specificity of circulating autoantibodies to a heterogeneous nuclear ribonuclear protein A1 (hnRNP A1), obtained by recombinant DNA technique, in different rheumatic diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), scleroderma, primary Sjogren's syndrome (SS), idiopathic Raynaud (IR), mixed connective tissue disease (MCTD), and healthy donors. All sera were tested by ELISA on hnRNP A1 protein. Positive values were obtained in 22% SLE, 19% scleroderma, 10% IR, 40% (2/5) MCTD, 5% SS, and 50% RA patients. The majority of patients reacted with the aminoterminal part (UP1) of hnRNP A1; however, some RA patients reacted also with the carboxy-terminal part that shows partial homology with keratin. Therefore, hnRNP A1 (UP1) can be considered a target of antinuclear autoimmunity in various rheumatic disorders.

An elevated level of autoantibodies against 48- to 50-kd keratins in the serum of patients with psoriasis

Studies on the anti-keratin intermediate filament autoantibodies (anti-KIF-Abs) in sera from psoriasis (Pso) patients were performed by immunoblotting and enzyme-linked immunosorbent assay (ELISA). According to their reactivities against keratin subunits (50, 56.5, 58, and 63-68 kd), sera were divided into four groups. However, no significant differences in these reactive patterns were found between healthy volunteers and Pso patients. In the second experiment, anti-KIF-Abs in sera from Pso patients, pustulosis palmaris et plantaris (PPP) patients, atopic dermatitis (AD) patients, systemic lupus erythematosus (SLE) patients, and healthy volunteers were determined by ELISA, using as substrate keratins purified from normal human stratum corneum and 48- and 50-kd keratins purified from psoriatic stratum corneum. The serum titers of anti-KIF-Abs against 48- and 50-kd keratins in Pso patients were significantly higher than those in PPP patients, AD patients, SLE patients, or healthy volunteers. The elevated titers of anti-KIF-Abs against the 48- and 50-kd keratins in sera of Pso patients showed a significant decrease with improvement of psoriatic lesions. The above results suggest that anti-KIF-Abs against 48- and 50-kd keratins in sera of Pso patients have some relevance to the severity of the disease and can be used as a marker for the evaluation of the disease activity of psoriasis.

Relation of antivimentin antibodies to anticardiolipin antibodies in systemic lupus erythematosus

Tests for antivimentin antibodies (AVA) were performed on 50 systemic lupus erythematosus (SLE) and 63 control sera by indirect immunofluorescence and enzyme linked immunosorbent assay (ELISA). The prevalence was significantly raised in SLE (38% and 50% of sera positive for IgM-AVA and IgG-AVA, respectively, by immunofluorescence; 36% and 64% of sera positive for IgM-AVA and IgG-AVA, respectively, by ELISA) in comparison with the control sera. A significant correlation existed between IgM-AVA, on the one hand, and anticardiolipin antibodies (ACA) and anti-single-stranded DNA (ssDNA), on the other. A stepwise principal component analysis demonstrated that IgM-AVA and IgG-AVA accounted for 71% of the total variance in SLE (50 patients x 5 parameters = total variance). Twenty ACA positive serum samples from patients with syphilis were therefore tested for the presence of AVA, but hardly any were found to be positive. IgM-AVA from patients with SLE were inhibited by cardiolipin and absorbed with ssDNA. An association between AVA positivity and arthralgia was also shown in SLE.

In vivo binding of immunoglobulin and complement to elastic structures in urinary bladder vascular walls in interstitial cystitis: demonstration by immunoelectron microscopy

An ultrastructural immunoperoxidase staining technique was used to identify and localize immune deposits in the urinary bladder vessel walls of patients with interstitial cystitis. Deposition of immunoglobulin together with the C3 component of complement was found in the subendothelial space and in endothelial basement membranes. More peripherally, deposits were often found associated with elastic fibers between smooth muscle cells. In these fibers the staining was confined to the microfibrillar coat. The findings suggest that elastic microfibrils act as target sites for the immunologic reaction occurring in vivo. Following binding of autoantibodies to antigens in bladder mucosa, activation of complement could be involved in the production of tissue injury and in the chronic self-perpetuating inflammation typical of this disease.

Natural IgM and IgG autoantibodies to epidermal keratins in normal human sera. I: ELISA-titration, immunofluorescence study

This paper presents a study of autoantibodies (autoAB) to keratins and to epidermis by a double approach associating a specific immunoenzymatic technique and immunofluorescence. The existence of natural autoAB to keratins in all normal human sera was asserted and the heterogeneity of natural autoAB to the epidermis explored. By a sensitive enzyme-linked immunosorbent assay we detected natural IgM and IgG autoAB to keratin polypeptides extracted from human plantar stratum corneum (SC) in 60 randomly selected normal human sera. The interindividual variation factors of their titers were about 100X in IgM and 50X in IgG antikeratin (AK) autoAB. The IgM and IgG AK autoAB titers varied independently. By a semiquantitative indirect immunofluorescence assay we detected in these sera IgM and IgG autoAB that labeled normal epidermis according to various morphologic patterns. The IgG autoAB labeled SC and suprabasal layers (SBL) in 57.4% of sera, SC in 20.4% and SBL in 7.4%. The IgM autoAB labeled SC and SBL in 52% of sera, SC in 24%, SC and SBL plus basal layer (BL) in 18%, and SBL in 2%. Like the titers, the patterns of IgM and IgG autoAB to epidermis were found to be unrelated. The IgG AK autoAB titers were found to significantly correlate only with the IgG autoAB directed to SC + SBL; the IgM AK autoAB titers only with the IgM autoAB directed to SC + SBL + BL. This showed that these patterns of labeling are typical for AK autoAB and that autoAB to SC, which could not be related to AK autoAB, exist in some normal sera. Antikeratin and antiepidermis IgM autoAB titers were found to be strongly correlated to total amounts of IgM assayed by radial immunodiffusion, indicating that the synthesis of these natural IgM autoAB vary in the same way as that of general IgM synthesis. For the AK and antiepidermis IgG autoAB, however, the same correlation to total serum IgG was found to be much weaker.

Antibody to intermediate filaments of the cytoskeleton in patients with Behçet's disease

Antibodies to 10-nm intermediate filaments (anti-IF) were determined in the sera of 30 patients with Behçet's disease (BD), in addition to C-reactive protein and C9, and an attempt has been made to determine whether the presence of anti-IF indicate disease activity. The vimentin type of anti-IF was found to be positive in 14 out of 30 patients with BD (47%), whereas it was positive in 35% of the patients with rheumatoid arthritis (20 cases), 16% of the patients with systemic lupus erythematosus (19 cases) and in only 9% of the normal controls. The anti-IF were predominantly IgG class and the titers in BD were significantly higher than those in normal controls. Out of the 14 patients with anti-IF, 10 showed significantly increased levels of serum C9 and 8 showed increased levels of CRP activity. Only one patient showed increased C9, but was negative for anti-IF and CRP. The presence of anti-IF in the patients' sera was found to be a more sensitive indicator, though not specific, for the clinical assessment of disease activity.

Antibodies to neurofilament protein in retinitis pigmentosa

Antibodies reactive with heterologous neural tissue were detected by indirect immunofluorescence microscopy in the sera of 17 of 34 patients with retinitis pigmentosa, one of 30 normal control sera, and a variable percentage of sera derived from subjects with diverse ocular and neurological diseases. These antibodies were also found both in disease-free first degree relatives and in spouses of patients with retinitis pigmentosa. Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis of human spinal cord components followed by immunoblots with sera under study revealed that the serum antibody was specific for the high molecular weight protein subunit of neurofilaments. No correlation was found between the presence of these antibodies and other immunological and clinical parameters in retinitis pigmentosa. These findings suggest that release of piled-up neurofilaments from damaged neurones in retinitis pigmentosa triggers B lymphocytes autoreactive to neurofilament antigens.

Rheumatoid arthritis synovial membrane contains a 62,000-molecular-weight protein that shares an antigenic epitope with the Epstein-Barr virus-encoded associated nuclear antigen

A monoclonal antibody, selected for reactivity with the Epstein-Barr virus (EBV)-encoded antigen EBNA-1, exhibited strong reactivity with the synovial lining cells in joint biopsies from 10 of 12 patients with rheumatoid arthritis (RA) and adherent cells eluted from these tissues. No staining of RA synovial membrane frozen tissue sections or eluted synovial-lining cells was obtained with monoclonal antibodies directed against other EBV-encoded antigens (anti-p160, anti-gp200/350) or with monoclonal antibodies directed against antigens encoded by cytomegalovirus, herpes simplex viruses, or human T cell leukemia virus type I. Among 12 osteoarthritis and normal synovial biopsies only rare reactive cells were noted. Characterization of the antigen(s) in RA synovium by the Western immunoblotting technique revealed a 62,000-molecular-weight (mol-wt) protein, in contrast to the 70,000-85,000-mol-wt EBNA-1 antigen found in EBV-transformed cells. The structural basis for the cross-reactivity of the RA synovial membrane 62,000-mol-wt protein and the EBNA-1 antigen appears to reside in the glycine-alanine rich region of these molecules. A rabbit antibody directed against a synthetic peptide (IR3-VI-2) derived from the glycine-alanine-rich region of EBNA-1 reacted with the 70,000-85,000-mol-wt EBNA-1 antigen in EBV-infected cells and with the 62,000-mol-wt molecule in RA synovial membrane extracts. Since strong antibody responses to EBNA-1 are known to exist in RA patients, these results suggest that immune responses to a cross-reactive antigen may play a role in the pathogenesis of RA.

Autoantibodies to intermediate filaments in experimental infections with Trypanosoma brucei gambiense

Sera from rats with chronic Trypanosoma brucei gambiense infection were tested for autoantibodies by an indirect immunofluorescence assay. All the sera contained IgM autoantibodies which reacted with blood vessel walls. On cultured vascular smooth muscle cells positive sera reacted with cytoplasmic filaments which were rearranged into perinuclear coils of filaments in colcemid-pretreated smooth muscle cells. These observations strongly suggest that the cytoplasmic autoantigens are intermediate filaments (I.F.). It is probable that the anti-intermediate filament autoantibodies result from polyclonal lymphocyte activation, since in rats experimentally infected with T.b. gambiense the appearance of these autoantibodies occurs already 1 week post-infection.

Immunofluorescent detection of anti-cytoskeleton antibodies using vinblastine-treated mononuclear cells

A reliable and reproducible immunofluorescence method is described for the detection of anti-cytoskeleton antibodies in human sera, based on the use of vinblastine-treated peripheral blood mononuclear cells as substrate. Three immunofluorescence patterns associated with antibodies to microfilaments, intermediate filaments and microtubules are readily identified.

Anticytoskeletal autoantibodies in the connective tissue diseases

The sera of 103 patients with connective tissue diseases were studied for the presence of anticytoskeletal antibodies by using an indirect immunofluorescence method. PTK2 cells fixed with paraformaldehyde and digitonin were used as substrate. Antibodies to intermediate filaments were detected in sera of 85.7% of polymyositis/dermatomyositis (PM/DM), 62.8% of systemic sclerosis, 54.5% of rheumatoid arthritis, and 37.5% of systemic lupus erythematosus patients, and in 42.5% of normal sera. High titers of these antibodies, which were IgM, were present in 30% of patients' and 5% of normal sera. Antibodies to microfilaments were present in 11.6% of patients' sera and absent in all control sera. These antibodies were IgM or IgG. The switch from an IgM to an IgG antibody was observed in 1 patient. An IgG antibody to the spindle poles and midbody of mitotic cells was present in the serum of 1 patient with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias). Antibodies to intermediate filaments and to microfilaments occur commonly in the connective tissue diseases, particularly in PM/DM, and are not detected with substrates or fixation methods used in routine antinuclear antibody testing.

Anti-intermediate filament antibodies, antikeratin antibody, and antiperinuclear factor in rheumatoid arthritis and infectious mononucleosis

Sera from patients with rheumatoid arthritis (RA), patients with infectious mononucleosis (IM), and blood donors were tested by indirect immunofluorescence for the presence of antikeratin antibody (AKA), antibody to cytoskeletal intermediate filaments of prekeratin or vimentin type (AIFA) and antiperinuclear factor (APF). In 81.9% of the RA sera and 92.5% of the IM sera AIFA of IgM class was found at titres up to and in some cases exceeding 1/160. In blood donors the incidence of AIFA was 26%, at titres not exceeding 1/20. AKA and APF, always of IgG class, were found in 54.2% and 73.6% of rheumatoid sera. A weak correlation was found in RA between the incidence of AIFA and APF. AKA was not present in either IM or blood donor sera, and APF was found in only 2.5% and 3.2% of IM or blood donors respectively.

Human vimentin autoantibodies preferentially interact with a peptide of 30kD mol. wt, located close to the amino-terminal of the molecule

Patients of some rheumatic autoimmune diseases like systemic lupus erythematosus have in their sera autoantibodies to vimentin, the main protein of intermediate sized filaments of the cytoskeleton of connective tissue cells. Immunoprecipitation and Western blotting techniques have been used to detect the interaction between human anti-vimentin autoantibodies and the two peptides that resulted from the cleavage of vimentin by N-chlorosuccinimide. Both methods and also immunoabsorption of sera with the isolated peptides suggest that the interaction of vimentin and immunoglobulins is mainly carried out through a peptide of 30kD mol. wt located close to the amino-terminal part of the vimentin molecule. The same results were obtained when a serum from a rabbit immunized with human vimentin was used.

Incidence of anti-intermediate filament antibody in serum samples of students with suspected glandular fever

Serum samples from 40 students with suspected infectious mononucleosis were tested for the presence of antibodies to intermediate filaments (AIFA) of the cytoskeleton. Twenty had antibodies to the Epstein-Barr virus capsid antigen before their illness, and during it their sera remained negative by the Paul-Bunnell test. The other 20 patients did not have antibodies to the Epstein-Barr virus capsid antigen before their illness and seroconverted during the illness. These patients (true infectious mononucleosis group) developed positive Paul-Bunnell tests. Sera from normal subjects (blood donors) were also tested for AIFA. AIFA was present in titres greater than 1/10 in 80% of the infectious mononucleosis group (mean titre 1/40-1/80), 10% of the Paul-Bunnell negative glandular fever group, and 8.5% of the normal blood donors.

Demonstration of anti-keratin antibodies by ELISA using keratin or thiol-containing compounds in urea as antigens

During the development of an enzyme-linked immunosorbent assay (ELISA) for the demonstration of anti-keratin antibodies (AKA) it was observed that rabbit anti-keratin antisera also reacted with polystyrene surfaces treated with beta-mercaptoethanol in 8 M urea (ME-urea). Sera from non-immunized rabbits or rabbits immunized with antigens unrelated to keratin failed to react. The specificity of the reaction was further assessed by absorption experiments and by testing affinity-purified AKA. IgM activity against ME-urea could be demonstrated in 62.5% of sera from patients with infectious mononucleosis and in 37.5% of sera from patients with rheumatoid arthritis, and there was a good correlation to the presence of AKA. Coating of the solid phase with compounds containing free SH groups in 4-8 M urea generated the antigen of this ELISA. The exact molecular configuration of this presumptive synthetic antigen is obscure, but the ME-urea ELISA seems to provide a simple way to detect anti-keratin antibodies of a certain specificity.

Stimulation of autoantibody production in normal blood lymphocytes by malaria culture supernatants

Supernatants from Plasmodium falciparum cultures containing soluble parasite material were mitogenic for normal human peripheral blood mononuclear cells (MNC) in vitro. This was evidenced by blast transformation and significant incorporation of 3H-thymidine and confirms earlier reports of the mitogenic potential of malaria parasites. Lymphocyte activation by these malaria derived products was polyclonal as demonstrated by increased secretion of IgA, IgG and IgM by the stimulated cells. Using rat tissues and Hep-2 cells as substrates, autoantibody activity was found in the IgM fraction of the secreted immunoglobulin. Speckled anti-nuclear (ANA) antibody, anti-globulins (rheumatoid factor) and anti-intermediate filament antibodies were produced by the stimulated lymphocytes. No significant immunoglobulin secretion with autoantibody specificity was found in control cultures in which normal MNC were incubated with supernatants from non-parasitized red cell cultures. The data supports the suggestion that polyclonal lymphocyte activation by parasite derived products occurs in vivo and, in addition, provides an explanation for the presence of autoantibodies in the serum of malaria patients.

Antibodies to vimentin intermediate filaments in sera from patients with systemic lupus erythematosus

Sera from patients with systemic lupus erythematosus and from healthy subjects were tested, using immunofluorescence and blotting techniques, for the presence of antibodies to intermediate filaments of the cytoskeleton of human skin fibroblasts. Both techniques showed that antibodies to intermediate filaments were found in a higher proportion of sera from patients (53%) than healthy subjects (9%). The antigen target was found to be the protein band that corresponded to vimentin (Mr 57,000).

Induction of anti-intermediate filament antibody in rabbits experimentally infected with Trypanosoma brucei brucei

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Antibodies to cultured rat heart cells in sera of patients with rheumatoid arthritis

Since heart lesions occur in many patients with rheumatoid arthritis (RA), sera from these patients were tested with an indirect fluorescent technique for antibodies reactive with rat heart cell cultures. Of 27 sera 22 had reactivity with non-muscle (nM) cells and 3 reacted with cultured beating muscle cells (M). Positive sera reactive with nM cells exerted complement-dependent cell cytotoxicity towards M cells. The nM antibodies were found to belong predominantly to the IgG class. They displayed no cross-reactivity with bovine collagen, human and bovine serum proteins, or human and sheep red blood cells. The relationship of these antibodies to the pathogenesis of RA heart lesions remains to be determined.

Multiple autoantigen binding capabilities of mouse monoclonal antibodies selected for rheumatoid factor activity

We report that approximately 1/4 of monoclonal rheumatoid factors produced by hybridomas derived from fusions of spleen cells from MRL/lpr/lpr mice with systemic lupus erythematosus (SLE) and arthritis exhibited multiple reactivities with other autoantigens, including dDNA , histones, and/or cytoskeletal-cytoplasmic elements. The patterns of reactivities of most of these clones differed, indicating that each had a separate B cell ancestor. Studies with eluted antibodies demonstrated that a single species of antibody molecules was responsible for the observed multiple reactivities. Inhibition experiments suggested that an antibody combining site may be large enough to accommodate dissimilar epitopes. These findings may provide further insights into the generation and extent of antibody diversity as well as the etiopathogenesis of systemic autoimmune diseases.

Antibody to intermediate filaments of the cytoskeleton in the sera of patients with acute malaria

Sera from 78 patients with acute malaria were tested for antibodies to intermediate filaments (IFs) by indirect immunofluorescence. Eighty-two per cent of the sera contained antibody which stained the IFs in human fetal skin fibroblasts and/or HEp2 cells. In contrast, only 8% of sera taken from blood donors gave weak positive staining of IFs and no staining was observed with 42 myeloma sera which were also tested as controls. In most cases autoantibodies were of the IgM class. Erythrocytes parasitized with Plasmodium falciparum failed to stain when reacted with non-malarial anti-IF antibody positive serum.

Human anticentriole autoantibody in patients with scleroderma and Raynaud's phenomenon

Unique autoantibody was found in sera from two different patients that reacted with centrioles of both cultured mammalian cells and human peripheral leukocytes as detected by the indirect immunofluorescent method. Sera from the same individuals, one with scleroderma and the other suffering from Raynaud's phenomenon, also stained the basal bodies of rat tracheal ciliated cells by the identical technique. Data from subsequent investigations have suggested that the antigen(s) involved in the reaction are water-insoluble protein(s) or polypeptide(s) associated with centrioles and are distinct from microtubular proteins or purine nucleoside phosphorylase.

Reactivity of serum antibodies to the keratin layer of rat esophagus in patients with rheumatoid arthritis

Serum antibodies reactive with the keratin layer of rat esophagus (AKA) were found in 46 of 80 (57.5%) rheumatoid arthritis (RA) patients. In contrast, AKA were present in only 7 of 82 (9.5%) patients with other types of rheumatic disorders and in 2 of 47 (4.2%) healthy subjects. AKA were not specific for RA, however, because in the former group, AKA were present in 4 of 20 (20%) systemic sclerosis patients and in 3 of 12 (25%) ankylosing spondylitis patients. AKA belong predominantly to the IgG class and are complement fixing. Although found in some RA joint fluids, AKA were not selectively concentrated in the joint fluid. Absorption of RA serum with type I human collagen or with human epidermal keratin did not remove AKA activity. The frequency of AKA in RA patients both negative and positive for DR4 was equal. There was no relationship between the frequency of AKA and the occurrence of other serum autoantibodies such as antibodies to intermediate filaments, smooth muscle, and nuclear antigens. Serum antibody reactive with human stratum corneum found in patients with psoriatic arthritis was shown to be different from AKA. Rabbit antiserum to human keratin did not inhibit the reaction of AKA against the keratin layer of rat esophagus. Autoimmunity to structural proteins including collagen, vimentin intermediate filaments, smooth muscle antigens, and keratin is a characteristic feature of RA.

In vitro induction of anti-intermediate filament antibody in lymphocyte cultures by Epstein-Barr virus

Serum antibodies reactive with intermediate filaments of the cytoskeleton (anti-IF antibodies) are often present in infectious mononucleosis, some other viral diseases, and rheumatoid arthritis. The mechanism of their production is not known, but it is possible that the formation of this and other autoantibodies result from polyclonal activation of B-cells. Peripheral blood mononuclear cells from subjects with or without serum anti-IF antibody were therefore cultured in the presence or absence of Epstein-Barr virus (EBV). IgM anti-IF antibody was produced in both unfractionated and T-cell-depleted cultures, but not in the supernatants of the same cells cultured without added EBV.