Autoantibodies against inosine-5'-monophosphate dehydrogenase 2--characteristics and prevalence in patients with HCV-infection

BACKGROUND

Indirect immunofluorescence (IIFT) on in house HEp-2 cell preparations revealed a novel antibody giving a granular cytoplasmic pattern not described before, which on two commercial cell preparations revealed a "rings and rods" pattern. This pattern was also observed in four HCV-RNA carriers and prompted the identification of the reactive antigen and the evaluation of the antibody prevalence in HCV-RNA carriers and control groups.

METHODS

The antigen's molecular weight was determined by radioimmunoprecipitation of 35S-methionine labeled cell proteins. Expression library screening and sequencing was performed by standard techniques using an oligo(dT)-primed human HeLa cell cDNA expression library. Antibodies against the novel antigen Inositol-5'-monophosphatdehydrogenase 2 (IMPDH2) were analyzed by IIFT, western blot, line blot, and radioimmunoprecipitation assay (RIPA). IIFT was performed on commercial HEp-2 cells and cells cultivated in house for 24 - 60 hours, with or without the IMPDH2 inhibitors mycophenolic acid (MPA) or ribavirin, and subjected to various fixation conditions. Western and line blots were performed with IMPDH2 synthesized in E. coli, RIPA with 35S-methionine-IMPDH2 from in vitro transcription/translation products. Sera screened were positive for HCV-RNA (108), HBV-DNA (100), anti-mitochondrial (31), anti-actin (42), and anti-nuclear antibodies (51) and negative for HCV-RNA (100) and blood donors (100).

RESULTS

IMPDH2 is capable of considerable intracellular rearrangements (upon action of inhibitors like MPA and ribavirin), which explains the contrasting immunofluorescence patterns in cells from different sources. By RIPA, proven to be the sole assay suitable for screening of anti-IMPDH2 in human sera, autoantibodies were found in 35.2% of HCV-RNA carriers and in low concentrations in 31% of anti-actin positive patients suspicious of autoimmune hepatitis. Antibodies reacted preferentially with conformational epitopes. Compared to the low concentration of anti-IMPDH2 found in other disease groups, high antibody concentrations were observed in HCV-RNA carriers.

CONCLUSIONS

The common occurrence of anti-IMPDH2 in HCV-RNA carriers may be related to ribavirin therapy, causing intracellular aggregation of IMPDH2 thereby altering its immunogenicity. In this study the "rods and rings" immunofluorescence pattern observed could be ascribed to anti-IMPDH2. Anti-IMPDH2 may cause difficulties in interpretation of immunofluorescence patterns in routine autoantibody testing.

Clinical characteristics of patients with myositis and autoantibodies to different fragments of the Mi-2 beta antigen

OBJECTIVES

To assess the clinical implications of autoantibodies directed against different parts of the Mi-2 beta autoantigen in patients with myositis.

METHODS

A systematic assessment of the clinical, laboratory, and histological characteristics of 48 anti-Mi-2 positive patients from six European centres was made. Anti-Mi-2 autoantibodies were determined with an ELISA using four overlapping fragments spanning the entire amino acid sequence of the autoantigen. Data were compared with results for a large group of anti-Mi-2 negative patients with myositis published previously.

RESULTS

Anti-Mi-2 autoantibodies were found in dermatomyositis, polymyositis, and inclusion body myositis. In general, myositis with anti-Mi-2 autoantibodies was characterised by relatively mild disease, sometimes accompanied by extra-muscular symptoms, including arthralgia, arthritis, Raynaud's phenomenon, and interstitial lung disease. Cardiac disease was not seen, and treatment response was fair. No differences were found between patients with autoantibodies to different fragments of the Mi-2 beta antigen, except for a potentially increased risk of cancer in patients with antibodies directed to the N-terminal fragment of the autoantigen.

CONCLUSIONS

Anti-Mi-2 autoantibodies are not a marker of a specific subtype of myositis. No significant differences between patients with autoantibodies to different fragments of the Mi-2 beta autoantigen are found, with the possible exception of an increased risk of cancer in patients with antibodies to the N-terminal fragment.

The third case of Doss porphyria (delta-amino-levulinic acid dehydratase deficiency) in Germany

Delta-aminolevulinic acid dehydratase (ALAD) deficiency porphyria, or Doss porphyria, was first reported in Germany in 1979. Only four bona fide cases of Doss porphyria have been reported to date that were confirmed by immunological and molecular analyses of their ALAD mutations. Here we describe the fifth case of Doss porphyria. A 17-year-old German male suffered from colicky abdominal pain and severe polyneuropathy for 2 years. Urinary delta-aminolevulinic acid (ALA) was increased 32-fold, and coproporphyrin 76-fold compared with the upper limit of their respective normal ranges. Urinary excretion of porphobilinogen (PBG) and uroporphyrin was only slightly increased. Faecal porphyrins were within the normal range. Erythrocyte zinc protoporphyrin concentrations were elevated 5.4-fold. ALAD activity in erythrocytes was decreased to 10% of the normal value, and was not activated by zinc and by dithiothreitol. Blood lead levels were within the normal range, excluding lead poisoning in the proband. Erythrocyte ALAD activity was about one-half of the normal value in both parents, whereas it was normal in the proband's brother. Urinary excretion of ALA, PBG and total porphyrins was within the normal range in both parents and the brother. Molecular genetic studies of the ALAD gene in the proband revealed two base changes, C to A and C to T, both in intron 3 at -11 bp upstream of the exon 3 start site. In addition to the proband, the father carried the (-11)C-to-T, while the mother carried the ALAD gene in the proband's brother. These findings suggest that the observed compound heterozygosity of the ALAD gene may be responsible for Doss porphyria in the proband. The proband was successfully treated with haem arginate infusion. The clinical condition improved, and urinary excretion of ALA and coproporphyrin fell to levels of approximately 50% compared with their pretreatment levels during acute relapses. The haem therapy was continued once weekly for 1 year. At the end of 1 year, urinary ALA and porphyrin levels were significantly lowered, and the proband is now almost free of clinical symptoms.

Autoantibodies against small nucleolar ribonucleoprotein complexes and their clinical associations

Sera from patients suffering from systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) have been shown to contain reactivities to nuclear components. Autoantibodies specifically targeting nucleolar antigens are found most frequently in patients suffering from SSc or SSc overlap syndromes. We determined the prevalence and clinical significance of autoantibodies directed to nucleolar RNA-protein complexes, the so-called small nucleolar ribonucleoprotein complexes (snoRNPs). A total of 172 patient sera with antinucleolar antibodies were analysed by immunoprecipitation. From 100 of these patients clinical information was obtained by chart review. Autoantibodies directed to snoRNPs were detected not only in patients suffering from SSc and primary Raynaud's phenomenon (RP), but also in patients suffering from SLE, rheumatoid arthritis (RA) and myositis (PM/DM). Antibodies against box C/D small snoRNPs can be subdivided in antifibrillarin positive and antifibrillarin negative reactivity. Antifibrillarin-positive patient sera were associated with a poor prognosis in comparison with antifibrillarin negative (reactivity with U3 or U8 snoRNP only) patient sera. Anti-Th/To autoantibodies were associated with SSc, primary RP and SLE and were found predominantly in patients suffering from decreased co-diffusion and oesophagus motility and xerophthalmia. For the first time autoantibodies that recognize box H/ACA snoRNPs are described, identifying this class of snoRNPs as a novel autoantigenic activity. Taken together, our data show that antinucleolar patient sera directed to small nucleolar ribonucleoprotein complexes are found frequently in other diseases than SSc and that categorization of diagnoses and clinical manifestations based on autoantibody profiles seems particularly informative in patient sera recognizing box C/D snoRNPs.

Clinical and serological characteristics of 125 Dutch myositis patients. Myositis specific autoantibodies aid in the differential diagnosis of the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of systemic diseases that include the familiar disease entities of dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). A subset of patients has unique autoantibodies which are specific for IIM (myositis specific autoantibodies; MSAs). We studied the clinical and serological characteristics of IIM in 125 Dutch patients. Sera were analysed by immunoblotting, enzyme-linked immunosorbent assay, and immunoprecipitation. The most frequently encountered MSA was the anti-Jo-1 autoantibody (20%), followed by anti-tRNAHis (6%), anti-Mi-2 (6%), and anti-SRP (4%). The presence of certain MSAs was clearly associated with specific clinical characteristics. Anti-Jo-1 and anti-tRNAHis were associated with the anti-synthetase syndrome, anti-SRP with PM with severe myalgia and arthralgia and a moderate response to immunosuppressive treatment. A novel finding was the presence of anti-Mi-2, not only in DM, but also in PM. MSAs were frequently present in DM/PM sera, but were hardly ever detected in the sera of IBM patients. The few IBM patients with MSAs demonstrated a significant response to immunosuppressive treatment. It can be concluded that MSAs define specific clinical syndromes within the spectrum of IIM and that they can assist in the differential diagnosis and treatment plan of these enigmatic disorders by virtually excluding IBM by their presence, and by potentially identifying a subgroup of steroid-responsive IBM patients.

Autoantibody profiles in the sera of European patients with myositis

OBJECTIVE

To determine the prevalence of myositis specific autoantibodies (MSAs) and several myositis associated autoantibodies (MAAs) in a large group of patients with myositis.

METHODS

A total of 417 patients with myositis from 11 European countries (198 patients with polymyositis (PM), 181 with dermatomyositis (DM), and 38 with inclusion body myositis (IBM)) were serologically analysed by immunoblot, enzyme linked immunosorbent assay (ELISA) and/or immunoprecipitation.

RESULTS

Autoantibodies were found in 232 sera (56%), including 157 samples (38%) which contained MSAs. The most commonly detected MSA was anti-Jo-1 (18%). Other anti-synthetase, anti-Mi-2, and anti-SRP autoantibodies were found in 3%, 14%, and 5% of the sera, respectively. A relatively high number of anti-Mi-2 positive PM sera were found (9% of PM sera). The most commonly detected MAA was anti-Ro52 (25%). Anti-PM/Scl-100, anti-PM/Scl-75, anti-Mas, anti-Ro60, anti-La, and anti-U1 snRNP autoantibodies were present in 6%, 3%, 2%, 4%, 5%, and 6% of the sera, respectively. Remarkable associations were noticed between anti-Ro52 and anti-Jo-1 autoantibodies and, in a few sera, also between anti-Jo-1 and anti-SRP or anti-Mi-2 autoantibodies.

CONCLUSIONS

The incidence of most of the tested autoantibody activities in this large group of European patients is in agreement with similar studies of Japanese and American patients. The relatively high number of PM sera with anti-Mi-2 reactivity may be explained by the use of multiple recombinant fragments spanning the complete antigen. Furthermore, our data show that some sera may contain more than one type of MSA and confirm the strong association of anti-Ro52 with anti-Jo-1 reactivity.

An ikaros-containing chromatin-remodeling complex in adult-type erythroid cells

We have previously described a SWI/SNF-related protein complex (PYR complex) that is restricted to definitive (adult-type) hematopoietic cells and that specifically binds DNA sequences containing long stretches of pyrimidines. Deletion of an intergenic DNA-binding site for this complex from a human beta-globin locus construct results in delayed human gamma- to beta-globin switching in transgenic mice, suggesting that the PYR complex acts to facilitate the switch. We now show that PYR complex DNA-binding activity also copurifies with subunits of a second type of chromatin-remodeling complex, nucleosome-remodeling deacetylase (NuRD), that has been shown to have both nucleosome-remodeling and histone deacetylase activities. Gel supershift assays using antibodies to the ATPase-helicase subunit of the NuRD complex, Mi-2 (CHD4), confirm that Mi-2 is a component of the PYR complex. In addition, we show that the hematopoietic cell-restricted zinc finger protein Ikaros copurifies with PYR complex DNA-binding activity and that antibodies to Ikaros also supershift the complex. We also show that NuRD and SWI/SNF components coimmunopurify with each other as well as with Ikaros. Competition gel shift experiments using partially purified PYR complex and recombinant Ikaros protein indicate that Ikaros functions as a DNA-binding subunit of the PYR complex. Our results suggest that Ikaros targets two types of chromatin-remodeling factors-activators (SWI/SNF) and repressors (NuRD)-in a single complex (PYR complex) to the beta-globin locus in adult erythroid cells. At the time of the switch from fetal to adult globin production, the PYR complex is assembled and may function to repress gamma-globin gene expression and facilitate gamma- to beta-globin switching.

Nucleotide sequence of a new HLA-DQB1 allele, DQB1*03033

HLA-genotyping by sequencing of the corresponding polymerase chain reaction (PCR) product allow the identification of a new HLA-DQB1 allele, DQB1*03033. To confirm the finding the entire exon 2 was sequenced.

The dermatomyositis-specific autoantigen Mi2 is a component of a complex containing histone deacetylase and nucleosome remodeling activities

Histone acetylation and deacetylation were found to be catalyzed by structurally distinct, multisubunit complexes that mediate, respectively, activation and repression of transcription. ATP-dependent nucleosome remodeling, mediated by different multisubunit complexes, was thought to be involved only in transcription activation. Here we report the isolation of a protein complex that contains both histone deacetylation and ATP-dependent nucleosome remodeling activities. The complex contains the histone deacetylases HDAC1/2, histone-binding proteins, the dermatomyositis-specific autoantigen Mi2beta, a polypeptide related to the metastasis-associated protein 1, and a novel polypeptide of 32 kDa. Patients with dermatomyositis have a high rate of malignancy. The finding that Mi2beta exists in a complex containing histone deacetylase and nucleosome remodeling activities suggests a role for chromatin reorganization in cancer metastasis.

The major dermatomyositis-specific Mi-2 autoantigen is a presumed helicase involved in transcriptional activation

OBJECTIVE

To characterize the complementary DNA (cDNA) and protein sequences of autoantigens recognized by anti-Mi-2 antibodies, using recombinant Mi-2 proteins for improved autoantibody detection.

METHODS

A cDNA expression library was immunoscreened, and cDNA isolation, alignment, and sequence analysis were performed. Northern blotting and in situ hybridization techniques were used. A recombinant protein (rMi-2) was synthesized. Immunoprecipitation of 35S-methionine-labeled HEp-2 cell proteins and immunoblotting of rMi-2 and natural nuclear proteins were performed. Immunofluorescence studies were done with anti-Mi-2 positive sera of dermatomyositis (DM) patients, and with human or rabbit antibodies specific for rMi-2. Antibody screening of systemic lupus erythematosus, rheumatoid arthritis, DM, and antinuclear antibody-positive human sera was performed using an rMi-2 protein enzyme-linked immunosorbent assay (ELISA).

RESULTS

A major antigen recognized by anti-Mi-2 positive sera of DM patients was found to constitute a 218-kd nuclear protein (218-kd Mi-2) encoded on chromosome 12 and to belong to the SNF2/RAD 54 helicase family. Human and rabbit antibodies that were affinity purified using the recombinant protein reacted with and precipitated a nuclear protein of similar size, which was also recognized by anti-Mi-2 sera. Anti-218-kd Mi-2 antibodies detected by rMi-2 protein ELISA seemed to be mainly restricted to sera from patients with DM.

CONCLUSION

The molecular characterization of the 218-kd Mi-2 antigen may contribute to our understanding of autoimmune phenomena in DM. The use of immunoreactive recombinant proteins allows structural and functional studies of the helicase and the development of sensitive and accurate antibody screening tests.

A C-terminally-anchored Golgi protein is inserted into the endoplasmic reticulum and then transported to the Golgi apparatus

Unlike conventional membrane proteins of the secretory pathway, proteins anchored to the cytoplasmic surface of membranes by hydrophobic sequences near their C termini follow a posttranslational, signal recognition particle-independent insertion pathway. Many such C-terminally-anchored proteins have restricted intracellular locations, but it is not known whether these proteins are targeted directly to the membranes in which they will ultimately reside. Here we have analyzed the intracellular sorting of the Golgi protein giantin, which consists of a rod-shaped 376-kDa cytoplasmic domain followed by a hydrophobic C-terminal anchor sequence. Unexpectedly, we find that giantin behaves like a conventional secretory protein in that it inserts into the endoplasmic reticulum (ER) and then is transported to the Golgi. A deletion mutant lacking a portion of the cytoplasmic domain adjacent to the membrane anchor still inserts into the ER but fails to reach the Golgi, even though this mutant has a stable folded structure. These findings suggest that the localization of a C-terminally-anchored Golgi protein involves at least three steps: insertion into the ER membrane, controlled incorporation into transport vesicles, and retention within the Golgi.

Interferon-gamma-inducible protein p16. A new target of antinuclear antibodies in patients with systemic lupus erythematosus

OBJECTIVE

To determine the cellular expression and localization of interferon-gamma (IFN gamma)-inducible protein p16, a new antigen specificity of antinuclear antibodies (ANA), and to evaluate the prevalence of anti-p16, particularly in SLE patients.

METHODS

Serum levels of anti-p16 were determined by immunoblotting with recombinant p16 and cellular p16 messenger RNA (mRNA) by Northern blotting. We also utilized immunoprecipitation of 35S-methionine-labeled proteins, immunostaining of blotted proteins of subcellular fractions, and immunofluorescence studies with affinity-purified rabbit and human anti-recombinant p16.

RESULTS

Protein p16 was localized within the nucleolus and nucleoplasm and constitutively expressed in Raji, HeLa, HEp-2, K562, and HL-60 cells. Synthesis of mRNA and protein was increased in the presence of IFN gamma. The prevalence of anti-p16 was 29% in 374 SLE patients (35% in those positive for anti-double-stranded DNA) and 0% in 188 healthy individuals. Anti-p16 was always accompanied by positive findings on indirect immunofluorescence for ANA.

CONCLUSION

Anti-p16 represents a main ANA specificity. Anti-p16 may help to elucidate IFN gamma-dependent nuclear processes and to link autoantibody production to states of IFN gamma activation.

HLA class II genes and antibodies against recombinant U1-nRNP proteins in patients with systemic lupus erythematosus. SLE Study Group

To investigate a possible involvement of HLA-class II alleles in the genetic predisposition for the formation of anti-U1-nRNP antibody-in systemic lupus erythematosus (SLE), genomic DNA of 178 patients was typed for the DRB1, DQA1 and DQB1 alleles using a polymerase chain reaction (PCR) and non-radioactive-oligonucleotide typing. Antibodies against recombinant U1-nRNP proteins (U1-A-, U1-C- and 70K-protein) were determined by ELISA. Anti-U1-C antibody was found in 26 (14.7%), anti-U1-A in 34 (19.2%) and anti-70K in 17 (9.6%) patients. A joint occurrence was observed for these antibodies against the recombinant U1-nRNP proteins: anti-U1-C and anti-U1-A antibodies occurred together more frequently than alone and than together with anti-U1-70K antibodies. The frequency of DRB1*04 was slightly increased in the patients with anti-U1-C as compared to the patients without anti-U1-C (P < 0.05, Pcorr = n.s., RR = 2.4). The DQA1*0301 allele, which is in linkage disequilibrium with DRB1*04, is found more frequently in anti-U1-C-positive than in antibody-negative patients. The DQB1*0303 allele, detected in 12 of 176 SLE patients, was absent in the patients with any of the antibodies against the U1-nRNP proteins. All these deviations may be due to chance alone. We concluded that the presence of antibodies against recombinant U1-nRNP proteins was not significantly associated with any HLA DRB1, DQA1 and DQB1 allele in our group of SLE patients.

Molecular genetic analyses of a 376-kilodalton Golgi complex membrane protein (giantin)

Molecular genetic analyses of a 376-kDa Golgi complex (GC) membrane protein (giantin) are described. The immunoglobulin G fraction of a human serum containing antibodies against GC antigens as revealed by indirect immunofluorescence microscopy with Hep-2 cells was used to screen a HeLa cDNA expression library, yielding four overlapping cross-hybridizing clones. Additional cDNA clones were retrieved from a lambda gt11 human thyroid cDNA library or generated by reverse transcriptase-mediated PCR from HeLa cell mRNA. Alignment of the clones resulted in a consensus cDNA of 10,300 bp encoding a protein of 376 kDa. The corresponding mRNA with a size of about 10 kb was detected by Northern (RNA) blotting of HeLa, Hep-G2, and Jurkat cell RNA. Sequence analyses of the protein revealed an extraordinarily high content of heptad repeats with the probability of forming coiled coils similar to the proteins of the myosin family. Five overlapping recombinant proteins covering the entire sequence were synthesized and used for antibody production in rabbits and for affinity purification of human and rabbit antibodies. Indirect immunofluorescence experiments also done with brefeldin A-treated Hep-2 and Pt K1 cells revealed an identical GC staining of both the affinity-purified human and rabbit antibodies. Double labeling experiments with antibodies against the GC marker mannosidase II as well as immunoelectron microscopic studies confirmed the localization of the protein within the GC. A corresponding endogenous large-molecular-mass protein of about 390 kDa was found in [35S]methionine-labeled Hep-2 cell lysates as well as in GC-enriched subcellular fractions from rat liver. The protein as well as the recently described proteins golgin-95 and golgin-160 (M. J. Fritzler, J. C. Hamel, R. L. Ochs, and E. K. L. Chan, J. Exp. Med. 178:49-62, 1993) may belong to a new group of Golgi proteins with a high content of heptad repeats which may exert functions in scaffold formation or vesicle transport. As far as can be concluded from immunological and personally communicated partial cDNA sequence data, the protein seems to be identical with a 400-kDa Golgi protein (giantin) recently described (A. D. Linstedt and H. P. Hauri, Mol. Biol. Cell 4:679-693, 1993). Therefore, we agreed to adopt the name giantin.

Hepatitis C virus infections in dialysis units: prevalence of HCV-RNA and antibodies to HCV

HCV infection causes serious complications in dialysis patients that lead to problems in management of patients in dialysis units. Determination of HCV-RNA is at present essential for monitoring the course of HCV infection. Reports concerning HCV-RNA in dialysis patients are mostly from Asian dialysis units; therefore, an analysis of dialysis patients in Europe was undertaken. From 1515 patients 2630 blood samples were screened for HCV-RNA and anti-HCV. Two-thirds of patients positive in an anti-HCV test containing a mixture of three antigens (EIA-II, Ortho) were further analysed for antibodies against these individual antigens. From 523 patients multiple samples were tested. Related on dialysis units from which all the attending patients were tested, mean prevalence of HCV-RNA was 8.4%, of anti-HCV 13.2%. Concerning all plasma samples from dialysis patients sent to our laboratory for investigation of HCV-RNA and anti-HCV the prevalence of HCV-RNA was 21.9%, of anti-HCV 23.1%, HCV-RNA was present in 76% of anti-HCV positive patients and in 4.1% of anti-HCV negative patients (1.3% of single and 6.8% of multiple tested patients). Acute and chronic infections with self-limited, persistent or intermittent viraemia were observed with changes and fluctuations of both HCV markers. With the exception of differences in onset of antibody production in some patients following acute infections, there were no major differences of dialysis patients compared to patients without dialysis treatment as far as antibody spectrum and detectability of HCV-RNA were concerned.

Macrogolgin--a new 376 kD Golgi complex outer membrane protein as target of antibodies in patients with rheumatic diseases and HIV infections

Antibodies against the Golgi complex (GC) were found by indirect immunofluorescence microscopy in the serum of two patients with sclerodermia and Sjögren syndrome. Serum from one patient was used to screen clones from an oligo (dT) primed HeLa cDNA expression library. Four overlapping cross hybridizing clones (G1, G12, G13, G14) were found. One additional 5' clone (G15) was retrieved from a random primed lambda gt11 human thyroid cDNA library by nucleic acid hybridization, exploiting sequence information of clone G12. Additional clones for both the 5' and 3' ends were generated by RF-PCR from HeLa cell mRNA. Alignment of the overlapping clones resulted in a consensus cDNA of 10,300 bp encoding a protein of 376 kD. A corresponding mRNA of about 10 kb was found in Northern blots of RNA from various cultured cells. The most distinct features of the protein were the extraordinarily high fraction of alpha-helical domains containing heptad repeats with the probability of forming coiled-coils and the structure similarities with the myosin family and the yeast intracellular transport protein USO1. Five overlapping cDNA fragments covering the entire open reading frame were used to synthesize recombinant proteins for affinity purification of the antibodies in the two patients' sera. By use of these affinity purified antibodies, staining of the GC of various cultured cell lines was reproduced. The antibody target was dissociated within 15 min after brefeldin A exposure of cultured cells, a phenomenon, which was fully reversible within 30 min after withdrawal of the drug. Sucrose step gradient separation of GC enriched microsomal fractions from rat liver showed a natural antigen of about 380 kD co-fractionating with the GC marker galactosyltransferase. KCl extraction, Triton X-114 partition, as well as trypsin digestion of microsomal fractions revealed that the hydrophilic protein has to be located on the cytoplasmatic surface of GC vesicles. Using the five blotted recombinant protein fragments, anti-GC antibodies were found in 18 of 164 (11%) HIV positive patients but in none of the 64 healthy controls. HIV patients as well as the two original patients showed a diverse antibody spectrum recognizing different epitopes of the recombinant proteins. The protein characterized herein, for which we propose the provisional name macrogolgin, constitutes the largest protein known so far associated with the GC.

[Different autoimmunity in Wegener's granulomatosis and microscopic polyangiitis]

Wegener's granulomatosis (WG) and microscopic polyangiitis (MP) are "small vessel" vasculitides which can serologically be discriminated measuring autoantibodies directed towards different target antigens (ANCA). In the present study we can demonstrate increased autoimmunity in patients with MP, as evaluated by measurement of thyroid microsomal and cardiolipin antibodies. Neither thyroid microsomal- nor myeloperoxidase-, nor cardiolipin antibodies were correlated to each other.

The chronic myelocytic cell line K 562 contains minor (m) as well as major (M) ber/abl fusion mRNAs

By searching for additional chimeric bcr/abl transcripts in K 562 cells characterized by major (M) bcr/abl fusions, a new mRNA, a minor (m) bcr/abl transcript, was detected. A practical implication of this finding is that the K 562 cell line can be used as positive control for the detection by the polymerase chain reaction of both types of transcripts for the diagnosis of Philadelphia chromosome associated leukemias.

No direct correlation between HLA-DPB1 and antibodies against recombinant Ro (SS-A)/La (SS-B) proteins in systemic lupus erythematosus. SLE Study Group

We investigated the association of HLA-DPB1 alleles with the occurrence of autoantibodies against Ro (SS-A) or La (SS-B) using recombinant 52 kD-Ro, 60 kD-Ro and La proteins in 177 German patients with systemic lupus erythematosus (SLE). A significant increase in the frequency of DPB1*0101 is observed in SLE patients compared to healthy controls (Pcorr.. < 0.004). Antibodies against 52 kD-Ro, 60 kD-Ro and La are tested by ELISA and are found with a frequency of 25.4%, 33.9% and 17.5% in the patients, respectively. An association with HLA-DPB1*0101 is observed for antibodies against La (P < 0.01) and 52 kD-Ro (P < 0.01), but not for 60 kD-Ro in the absence of La/52 kD-Ro. Since there is a strong linkage disequilibrium between DPB1*0101 and DR3 in the normal population and in SLE patients, and since there is an association between DR3 and SLE, as well as between DR3 and the occurrence of recombinant Ro/La antibodies in SLE patients, we investigated whether DPB1*0101 is associated per se or via linkage disequilibrium with DR3. DPB1*0101 in the absence of DR3 is not more common in patients than in controls and not in patients with autoantibodies to Ro and La than without autoantibodies. We conclude that there is no evidence for a direct involvement of DPB1*0101 in the production of Ro/La autoantibodies in SLE patients.

Autoantibodies against topoisomerase I detected with the natural enzyme and overlapping recombinant peptides

Antibodies against topoisomerase I (anti-topo I, anti-Scl-70) are regarded as a marker of systemic sclerosis. The various frequencies of anti-topo I detected in those patients depends at least in part on the test design and the kind of the antigen used. We therefore analyzed three overlapping recombinant topo I fragments (N-terminal, center and C-terminal part of the molecule) covering the full length of the enzyme for substitution of highly purified natural antigens (n-topo I) in ELISA for antibody screening. 49 of 50 sera reacting with n-topo I in ELISA also recognized the recombinant C-terminal topo I fragment under identical test conditions, 37 sera recognized the recombinant center and two sera the recombinant N-terminal peptide. All sera reactive with the N-terminal and center peptide reacted with the recombinant C-terminus which therefore may substitute for the natural antigen. In immunoblot assays 92% (46/50) of the sera reacted with n-topo I and 86% (43/50) with the recombinant C-terminal peptide. Immunoblots therefore seem to be less sensitive for detecting anti-topo I antibodies than ELISA regardless the source of the antigen used. In a screening of 696 sera submitted for routine antibody tests the recombinant peptide ELISA on the other hand detected two sera which did not react with n-topo I in ELISA. Because of the high rate of agreement within the results obtained with the two antigens, n-topo I can be substituted by the recombinant peptide ELISA allowing better standardization and interlaboratory comparison of results.

Anti-LKM-1 antibodies determined by use of recombinant P450 2D6 in ELISA and western blot and their association with anti-HCV and HCV-RNA

Several subtypes of anti-liver-kidney microsome antibodies (LKM) are known. LKM-1 antibodies associated with autoimmune chronic active hepatitis recognize P450 2D6, a cytochrome P450 mono-oxygenase. The frequent association of anti-LKM-1 antibodies and hepatitis C virus (HCV) infections and the probable existence of an infectious and autoimmune form of anti-LKM-1-associated hepatitis, requiring different therapeutical strategies, necessitates the exact determination of anti-LKM-1 specificities. Therefore, we compared various antibody tests (immunofluorescence, ELISA with recombinant P450 2D6, and Western blot with recombinant and natural antigens and agargel double diffusion) with sera of 27 anti-LKM-1-positive chronic active hepatitis (CAH) patients, with 61 sera harbouring anti-mitochondrial antibodies, 100 sera each from HCV-RNA-positive and HCV-RNA-negative patients, and 50 sera of healthy persons. Western blot techniques using recombinant MS2-polymerase P450 2D6 fusion protein were found to be the most sensitive and specific method for anti-LKM-1 antibody determination in routine laboratory. The recently recognized association of anti-LKM-1 antibody and HCV infection was confirmed by the results of this study. In anti-HCV and HCV-RNA-positive patients with anti-LKM-1 antibodies there was a preponderance of males with higher mean age and lower antibody titres. The results support the hypothesis of the existence of an autoimmune as well as an infectious (HCV triggered) subgroup of anti-LKM-1-positive hepatitis.

Dose dependent suppression of mineralocorticoid metabolism by different heparin fractions

One neglected side effect of heparin therapy is the inhibition of adrenal aldosterone production leading to occasionally life-threatening hyperkalaemia. This is only reported with (therapeutic) high doses (greater than or equal to 20.000 IU). The complex interplay of mineralocorticoid metabolites was studied in 29 subjects with unfractionated (UFH) and low molecular weight heparin (LMWH). Both heparins altered mineralocorticoid metabolism in a dose dependent manner. Whereas no effect was observed with UFH 2 x 5000 IU sc/day or LMWH 2500 a FXa U sc/day, higher doses significantly suppressed aldosterone and 18-hydroxycorticosterone production in plasma and urine. Three out of seven patients receiving UFH 3 x 7500 IU sc/day developed hyperkalaemia. This study shows the threshold dosage of UFH leading to suppression of mineralocorticoid metabolism in man and provides information that LMWH as well as UFH can suppress mineralocorticoid production. With respect to therapeutic implications it is important that LMWH at 2500 a FXa U sc/d had no effect on mineralocorticoid metabolism in contrast to UFH at a dosage currently used for prevention of thromboembolism (3 x 5000 IU sc/d).

The genetic basis of Ro and La antibody formation in systemic lupus erythematosus. Results of a multicenter study. The SLE Study Group

Antibodies against Ro and La, including recombinant La and recombinant 60 kD-Ro, were determined by counter immunoelectrophoresis and ELISA in over 300 central European systemic lupus erythematosus (SLE) patients. The presence of both Ro and La antibodies was strongly associated with the MHC haplotype B8-C4AQ0-DR3-DQ2, the association being strongest for DR3. After exclusion of all B8-DR3 positive patients only DR3 positive patients still showed an increased incidence of Ro and La antibodies, suggesting DR3 as the primary association factor. High titers of La antibody, but not of 60 kD-Ro antibody, were also significantly associated with the presence of DR3. Other DR and DQ antigens or heterozygous DQ combinations were not significantly associated with Ro and La antibodies.

[Rapid diagnosis of tuberculosis by the polymerase chain reaction (PCR)]

The polymerase chain reaction (PCR) was used for the detection of Mycobacterium tuberculosis DNA. More than 2000 different clinical specimens were analyzed by this assay. The efficiency of two different methods for processing the DNA from biological material was analyzed. DNA amplification was done according to standard protocols by amplifying a segment of 402 bp of the 65 kD mycobacterial gene, electrophoretic separation of the amplification product followed by Southern transfer and hybridization with a Mycobacterium tuberculosis-specific probe or by a semi-nested amplification procedure in which the initial amplification product was reamplified by a second round with a Mycobacterium tuberculosis-specific primer. The specificity of primers and probe for mycobacterial DNA was proven by testing 70 of class-I microorganisms, as well as 20 different strains and own isolates of Mycobacterium tuberculosis and 67 strains of 25 different MOTTs. Some of the amplification products were sequenced. The clinical relevance of the results and the sensitivity of the PCR method were confirmed by simultaneous quantitative bacterial culture from the same clinical specimens. The results of conventional culture method received after 8 to 10 weeks culture time correlated with the results from PCR obtained within 12 hours in 95.4% in the semi-nested amplification procedure. The discrepancy of 4.6% was caused by positive results of PCR and negative cultures which might be due to the higher sensitivity of PCR compared to culture technique. The results show that PCR may be used for detection of Mycobacterium tuberculosis in clinical specimens. The specificity can be regarded as largely proven, advantages are velocity and sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

A recombinant 70K protein ELISA. Screening for antibodies against U1snRNP proteins in human sera

Antibodies to uridylic acid rich small nuclear ribonucleoprotein particles (UsnRNP) are mainly detected in patients with systemic lupus erythematosus (SLE) or mixed connective tissue disease (MCTD). Particularly those directed against epitopes of the 70K protein of U1snRNP serve as important markers for the diagnosis of MCTD. To establish an ELISA for determination of anti-70K protein antibodies in patients' sera a 1239 bp long cDNA insert coding for the epitopes of the 70K protein was ligated into a fusion expression vector. The bacterially expressed fusion protein was purified by chromatography on DEAE cellulose. Microtiter plates were coated with the fusion protein as well as with partially purified calf thymus extract (CTE) containing all natural UsnRNP antigens and RNase digested calf thymus extract (CTERNase) in which the natural 70K antigen was destroyed by the nuclease treatment. 10,888 sera of patients with suspected or overt rheumatic disease were analyzed for antibodies against these antigens simultaneously. Antibodies against CTE or CTERNase were not detected in 9123 sera, none of these showed reactivity with the 70K protein indicating a high degree of specificity of the assay. Positive results in each the 70K protein, CTE as well as the CTERNase ELISAs were obtained with 474 sera. 319 sera were only positive with CTE and 70K protein. Of these 793 anti-70K protein ELISA positive sera, 79% could be confirmed by immunoblot. Of 967 sera reacting with CTE and CTERNase but not with the recombinant 70K protein, 31% contained antibodies against various other UsnRNP proteins as shown by immunoblotting. 2.4% of these sera revealed also antibodies against the 70K protein. The use of the recombinant 70K protein as antigen meets the criterion for a simple and specific assay to detect anti-U1snRNP antibodies. Nevertheless, the sole use of this recombinant protein for anti-U1snRNP antibody screening may not be appropriate, because antibodies against other frequently occurring U1snRNP proteins (A, C) cannot be detected with this test. Therefore it should be used together with a natural UsnRNP antigen until further studies in patients with well established diagnoses will show whether natural antigens may be omitted.

[Hepatitis C virus: sequence homology of a European isolate and divergence from the prototype]

The polymerase chain reaction (PCR) detected specific hepatitis C viral (HCV) RNA sequences in liver biopsies from two patients with chronic hepatitis, in the tissue of a liver implantate, in plasma from four chronic non-A, non-B hepatitis (NANBH) patients and, for the first time, in an infectious anti-D-immunoglobulin preparation. A comparison of the viral sequences coding for a region for the nonstructural NS3 protein from the liver tissues revealed only a very small degree of sequence divergence on the cDNA as well as on the amino acid level (between 0 and 5%). The sequence similarities of the RNA isolated from plasma of the four chronic NANBH patients and the anti-D-immunoglobulin preparation were partly somewhat lower but altogether also high (between 90 and 100%). In contrast, all eight cDNA and amino acid sequences exhibited a significantly higher degree of divergence in comparison with the HCV prototype sequence (between 29 and 32%) than among themselves (between 0 and 10%). This unexpected high sequence similarity of the eight European isolates and their low homology to the Northamerican prototype sequence is indicative for the existence of different types of HCV. This will be important not only for epidemiological studies but also for the development of effective diagnostic procedures and vaccines. Concerning the pathogenesis of NANBH, a double infection or a helper mechanism has to be considered: in addition to the C virus, sequences of an other virus particle were found in the infectious IgG preparation as well as in the liver biopsies.

[The demonstration of hepatitis B virus DNA with the polymerase chain reaction]

Results with the polymerase chain reaction and conventional DNA hybridizing technique (dot-blot) for the detection of hepatitis B virus (HBV) DNA were compared for 439 patients. In 261 patients who were positive for HBs antigen (Ag), HBV DNA was demonstrated with the polymerase reaction in all of the 69 HBe-Ag positive sera (dot-blot 56%), as well as in 81 (62%) of 131 anti-HBe positive sera (dot-blot 5%), in 29 (48%) of 61 HBe marker negatives (dot-blot 3%) and in six (29%) of 21 delta positive sera. Among HBs-Ag negative patients, HBV DNA was detected in six (22%) of 27 anti-HBc positive sera, but not in sera (n = 50) which were both anti-HBc and anti-HBs positive, as well as in HBV marker negative patients with liver disease (n = 30) and healthy controls (n = 50). If infectiousness is to be checked or in case of double infection, the more sensitive polymerase chain reaction is to be recommended for the detection of HBV DNA. HBe-Ag positive patients must be considered as infectious: tests for HBV DNA can in general be omitted.

[Autoantibodies against U1-n-RNP (ENA)--detection using a recombinant 70-kDa protein]

An ELISA for the demonstration of antibodies to RNP antigens (ENA) in sera of patients with systemic rheumatic diseases was developed using the recombinant 70-kDa protein, a marker antigen of U1-n-RNP. The specificity and sensitivity of the method was evaluated with 3588 patients' sera. The results were compared with those obtained by natural antigens isolated from calf thymus and Western blot analysis using HeLa-cell nuclear extracts. The test was found to be specific and sensitive and to be superior in routine laboratory screening than the other tests commonly used.

[IgM kappa immunocytoma in IgM-kappa monoclonal gammopathy]

A case of monoclonal gammopathy of the IgM kappa class is reported, in which a large number of reddish-brown, non-itching papules, reaching at maximum the size of peas and aligned in a follicular arrangement, had been seen to an unchanged extent on the left upper thigh for 6 years. Both histologically and immunohistologically, a B-cell lymphoma releasing kappa-type IgM was demonstrated. The clinical picture obtained was different from that of the few other cases reported in the literature, which have always involved either large-surface infiltrates or much larger nodes, either solitary or irregularly arranged.

[Hepatitis non-A, non-B-associated DNA--demonstration of DNA in proven infectious anti-D-immunoglobulin]

An anti-D-immunoglobulin preparation implicated in a hepatitis non-A,non-B transmission was analyzed for the presence of a DNA, which was originally isolated, cloned and sequenced from feces of a patient with posttransfusion HNANB. The investigation was performed by a DNA polymerase chain reaction using synthetic oligoprimers. Commercially available immunoglobulin preparations served as controls. The demonstration of identical DNA sequences in the infectious material speaks in favour of this up to now unknown circular and partially double-stranded DNA to be a virus genome involved in hepatitis non-A,non-B.

[A hepatitis non-A, non-B-associated substance in the feces--identification and cloning of a partially double-stranded circular DNA]

By means of a radioimmunoassay a substance excreted in feces could be detected in patients with hepatitis non-A,non-B (HNANB). Feces extracts of patients with sporadic and posttransfusion HNANB as well as of healthy persons were precipitated with PEG, digested with RNase and DNase and separated on CsCl. In HNANB-patients a RIA-positive material with a density of 1.3 g/ml CsCl could be detected which contained a partially double-stranded circular DNA. Cloning of this DNA in lambda-phase resulted in DNA of about 5 Kb, which hybridized with feces DNA under stringent conditions. The 5 Kb-DNA were mapped with different restriction enzymes. A 1.5 Kb EcoRi-fragment cross-hybridizes with HBV-DNA. No hybridization and sequence homologies were found with human, viral and procaryotic DNA as well as with plasmid and phage DNA (data base EMBL, Heidelberg). It is assumed that the DNA excreted in feces of HNANB-patients represents a viral genome not detected so far.

[Diagnostic significance of the detection of hepatitis B virus DNA in acute and chronic hepatitis]

1065 sera from patients with acute and chronic hepatitis-B-virus-(HBV-) infections, double infections (HBV, HAV, nonA-nonB, delta-Ag) as well as patients with HBs-Ag-negative hepatitis (HAV, nonA-nonB) and healthy subjects were investigated for the presence of hepatitis-B-virus-DNA using molecular hybridisation. The sensitivity of the method was 0.1 pg HBV-DNA/100 microliters. HBV-DNA could be detected in 62% of cases of HBs-Ag-positive sera with HBe-Ag, in 8.9% with anti-HBe and in 11% of e-marker free sera. In acute hepatitis HBV-DNA was present in 44%, in chronic hepatitis in 71% of HBe-Ag-positive sera. In HBs-Ag-negative sera containing only anti-HBc, HBV-DNA, depending on the anti-HBc-titre, was present in 13-24% of cases. HBV-DNA could not be detected in patients with HBV infections (anti-HBc and anti-HBs positive) in the past or in HBV-marker-negative hepatitis. Follow-up investigations on acute and chronic HBV-infections showed that the disappearance of HBV-DNA generally preceded the disappearance of HBe-antigen by about 2-3 weeks. In chronic hepatitis the time interval can amount to several months or years. Double infections with other hepatotropic viruses (nonA-nonB and delta-virus) can lead to a temporary suppression of HBV-DNA replication.

Cutaneous papulo-vesicular eruptions in non-A, non-B hepatitis

A relapsing papulo-vesicular rash with or without pruritus was observed in 54 out of 148 patients (36%) with posttransfusion or sporadic, acute or chronic, non-A, non-B (NANB) hepatitis. The predominant location was the trunk and the anterior surfaces of the upper extremities. The face was affected less often. The eruptive phase was accompanied by general symptoms and increases in aminotransferases and gamma-GT values. The nature of the eruption was consistent with cutaneous reactions as frequently seen in enterovirus infections. No predominance was found for special groups of patients when the skin lesions were correlated to either sex, mode of infection or pattern of transaminase elevation (i.e. monophasic or bi-, and multi-phasic).

[Lymphocytes and lymphocyte subpopulations]

Human lymphocytes can be subdivided in several subgroups by means of their membrane markers. T-lymphocytes, B-lymphocytes and natural killer cells can be enumerated with monoclonal antibodies reacting with surface glycoproteins or with antibodies against surface immunoglobulins. The analysis of the membrane antigens and receptors leads to a better understanding of lymphocyte differentiation from stem cells to immunocompetent mature cells. T-lymphocytes can be subdivided in a helper cell fraction expressing a characteristic T4-antigen and a suppressor cell fraction with the T8-antigen response. Imbalances in the helper/suppressor ratio can be seen in immunodeficiency syndromes as AIDS, in viral infections and autoimmune disorders. The diagnostic relevance of lymphocyte differentiation in several diseases will be discussed.

[Systemic light-chain disease as a complication of plasmacytoma]

An asymptomatic multiple myeloma of the kappa-light chain type was found in a patient with nephrotic syndrome and renal insufficiency. Light microscopy showed nodular glomerulosclerosis of the kidney similar to diabetic glomerulosclerosis. Diabetes mellitus could not be demonstrated. kappa-Light chain deposits could be shown by immunohistology in the mesangium and the glomerular and tubular basal membrane. In addition, massive kappa-light chain deposits in the sinusoidal walls of the liver and at the dermoepidermal junction of the skin and in the corium were found.