Solute transport across the tonoplast of barely mesophyll vacuoles: Mg2+ determines the specificity, and ATP lipophilic amino acids the activity of the amino acid carrier

After stimulation with ATP and in the absence of divalent cations, isolated barely mesophyll vacuoles exhibited massive solute fluxes across the tonoplast, measured either as efflux of endogenous solutes or as uptake of radioactive-labeled compounds. Transported solutes were ions (particularly K+, NO3-, Cl-) and amino acids (for example, ala, arg, asp, gln, leu, met). Addition of Mg2+ in excess of added ATP inhibited fluxes of inorganic ions and of positively charged amino acids, but not, or to a smaller extent, those of neutral amino acids. Thus, Mg2+ increased the specificity of the carrier for amino acids such as alanine and glutamine. All ATP-stimulated transport processes were sensitive towards inhibition by lipophilic amino acids, for example by leucine and phenylalanine. After stimulation with sulfhydryl reagents, the inhibitory properties of Mg2+ and lipophilic amino acids were lost. These data concur with the hypothesis of a single transporter which exhibits a channel-like structure with a low degree of substrate selectivity in the absence of Mg2+, and which functions as a neutral amino acid carrier in the presence of Mg2+.

Sneddon's syndrome and phospholipid antibodies

We present a case of Sneddon's syndrome with high titers of antiphospholipid antibodies (APLA), in which the leading symptom was an incapacitating memory defect. MRI revealed vasculitic lesions of the central nervous system (CNS). Therefore immunosuppressive therapy was started with steroids and cyclophosphamide pulses. The transient beneficial effects of such a therapy will be discussed.

The B cell repertoire of patients with rheumatoid arthritis. Frequencies and specificities of peripheral blood B cells reacting with human IgG, human collagens, a mycobacterial heat shock protein and other antigens

Using a potent in vitro limiting dilution culture system, we have activated human peripheral blood B cells to proliferate and to differentiate into antibody-secreting cells (ASC). Under these conditions 25-100% of B cells are clonally expanded and produce IgM, IgG or IgA. Culture supernatants were tested for antibodies binding to human IgG-Fc fragments (RF), the 65-kD heat shock protein of Mycobacterium bovis (hsp60), human collagens type I, II, IV, V, transferrin, lactoferrin, albumins, and gelatine. All blood samples contained precursors of ASC (p-ASC) able to produce IgM binding to these antigens in frequencies above 0.03% of B cells. Most interestingly, a significant difference exists between rheumatoid arthritis (RA) patients and controls, concerning the relative frequencies of p-ASC able to produce monospecific or multireactive RF. Whereas most p-ASC(RF) in RA patients are monospecific (mean ratio 3.7), most p-ASC(RF) in healthy control persons are cross-reactive with at least one of five other antigens tested (mean ratio 0.2). The data suggest a disease-specific expansion of p-ASC committed to the production of monospecific rheumatoid factors.

Susceptibility to relapsing polychondritis is associated with HLA-DR4

OBJECTIVE

To determine the frequency of HLA class II antigens in Caucasian central European patients with relapsing polychondritis (RP).

METHODS

HLA class I, DR, and DQ specificities were identified in 41 patients with RP, and the frequencies were compared with those in 204 healthy, unrelated control subjects. HLA typing was performed using the standard complement-dependent microcytotoxicity assay. HLA-DR genotyping of 12 DR4-positive RP patients and 57 controls was performed by allele-specific oligonucleotide probing after amplification of genomic DNA by polymerase chain reaction.

RESULTS

A significant increase in DR4 antigen frequency was found in the patients (56.1%) as compared with that in healthy controls (25.5%) (Pcorr < 0.001). Genotyping of DR4-positive patients and controls revealed no predominance of any DR4 subtype.

CONCLUSION

There are important clinical similarities and overlaps between RP and rheumatoid arthritis (RA). In RA, the association with DR4 has been well established. Our findings show that although there is a DR4 association with RP, the situation is sufficiently distinct from that of RA to imply considerable differences in pathogenesis of the two conditions.

[Chronic recurrent polychondritis]

Relapsing polychondritis (RP) is a recurrent, chronic und rare disease of unknown etiology, characterized by inflammation of cartilaginous structures of the ears, nose, respiratory tract and joints. The association with HLA-DR4 and the occurrence of antibodies to type-II collagen and other autoantibodies suggest that an immunologic mechanism is involved in its pathogenesis. In about 30% of occurrences RP is associated with other rheumatic or autoimmune diseases. Ocular inflammation, involvement of the cardiovascular system, skin, central nervous system and audiovestibular organ are most probably caused by vasculitis. The course of RP is variable. Severity and outcome primarily depend on the occurrence of associated autoimmune diseases and vasculitis. According to the activity and systemic manifestations, medical treatment includes nonsteroidal antiinflammatory drugs, corticosteroids and cytotoxic agents.

Cross-linking of presynaptic calcium channels: a mechanism of action for Lambert-Eaton myasthenic syndrome antibodies at the mouse neuromuscular junction

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission. Immunoglobulin G (IgG) autoantibodies act presynaptically to cause functional loss of Ca2+ channels by down-regulation. This in turn causes reduced release of acetylcholine in response to nerve stimulation (i.e. reduced quantal content). We show here that in vitro application of LEMS IgG for 24 h was as effective in causing reduced quantal content in mice as injecting animals with the antibody for 2 days. Furthermore, incubation with divalent (F(ab')2) fragments also significantly reduced quantal content. However, monovalent (Fab) fragments were without significant effect. No antibody or antibody fragment preparation affected spontaneous release. Whole LEMS IgG and F(ab')2 (but not Fab) fragments also inhibited K(+)-evoked 45Ca2+ flux in a small cell carcinoma cell line. These findings present functional evidence that LEMS IgG-induced down-regulation of nerve terminal Ca2+ channels arises due to antibody cross-linking of these channels.

HLA-DRB1 gene sequences in HLA-DR4 positive and negative patients with rheumatoid arthritis

The second exon of the DRB1 gene encoding for the first domain of the HLA-DR beta 1-chain was sequenced in 16 patients (10 DR4/DR1 positive, 6 DR4/DR1 negative) with seropositive rheumatoid arthritis (RA). We could confirm the strong association of susceptibility to RA with functionally equivalent conformations on otherwise distinct MHC molecules. At least one HLA-DR allele in all of the analysed DR4 or DR1 positive patients showed such an epitope with a minimal variability limited to residue 71. However, in HLA-DR4 and -DR1 negative patients such a similar epitope could not be detected.

Current therapy of systemic sclerosis (scleroderma)

Treatment of systemic sclerosis (scleroderma) presents a challenge to both the patient and the physician. Established approaches include long-term physiotherapy, disease-modifying agents such as D-penicillamine, and treatment of organ involvement. These efforts are often unsatisfactory since the results are poor. However, recent advances include treatment of Raynaud's phenomenon (plasmapheresis, stanozolol, and prostacyclin analogues), scleroderma renal crisis (angiotensin-converting enzyme inhibitors), and gastric hypomotility (cisapride). This article covers the current approaches to the disease-modifying therapy including those related to the function of collagen-producing fibroblasts, vascular alterations, and the cellular and humoral immune system, as well as treatment of involved organs.

[Anti-neutrophil-cytoplasmic antibodies in rheumatoid arthritis: specificity and clinical relevance?]

Sera of 90 patients fulfilling the criteria of the American Rheumatism Association for the rheumatoid arthritis (RA) were screened for antibodies against neutrophil cytoplasmic antigens (ANCA) by an indirect immunofluorescence test. All sera were also tested for rheumatoid factor (Waaler-Rose-Test, WRT), C-reactive protein (CRP), antinuclear autoantibodies (ANA) on HEp-2 cells. 40% of the 90 sera showed ANCA-positive reactions. c-ANCA and p-ANCA types were both observed but the latter was by far more common (91%). The peculiarity of the p-ANCA pattern was a fine granular perinuclear staining. Antibodies against myeloperoxidase (MPO) were negative in all RA sera tested. So far we found a significant relationship between positive ANCA staining, functional Steinbrocker grades, and rheumatoid factor. No significant correlation was observed with extraarticular manifestation, CRP, therapeutic modalities (gold) or MHC antigens. Currently the nature of the neutrophil antigen involved is under investigation.

Complement split product C3d as an indicator of disease activity in systemic lupus erythematosus

In order to investigate, if complement levels can be used as an indicator of clinical activity in systemic lupus erythematosus (SLE), levels of C3, C4, CH50, and C3d were measured in 79 patients, 41 with inactive, 31 with moderately active and 7 with severely active disease. Our study shows that C3d, and particularly the C3d/C3 ratio, provide sensitive markers for disease activity in SLE. Since C3d is a direct measurement of complement turnover, it reflects complement activation better than C3, C4 and CH50.

Synaptotagmin: a Lambert-Eaton myasthenic syndrome antigen that associates with presynaptic calcium channels

Plasma from patients with Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease of neuromuscular transmission, contains antibodies that immunoprecipitate 125I-omega-conotoxin GVIA labeled-calcium channels solubilized from rat brain. These antibodies label a 58-kDa protein in Western blots of partially purified 125I-omega-conotoxin receptor preparations. Monoclonal antibody 1D12, produced by immunizing mice with synaptic membranes, has similar properties as these LEMS IgG. 1D12 antigen was purified by immunoaffinity chromatography and shown to bind LEMS IgG. The antigen was identified by immunoscreening a rat brain cDNA library with mAb 1D12 and found to have strong homology to the synaptic vesicle protein synaptotagmin. These antibodies immunoprecipitate calcium channels by binding to synpatotagmin, an associated protein. We suggest that the interaction between synaptotagmin and omega-conotoxin sensitive calcium channels plays a role in docking synaptic vesicles at the plasma membrane prior to rapid neurotransmitter release. Autoantibody binding to a synaptotagmin-calcium channel complex may be involved in the etiology of LEMS.

Paraneoplastic cerebellar degeneration. III. Cerebellar degeneration, cancer, and the Lambert-Eaton myasthenic syndrome

We studied nine patients with a subacute onset of a pancerebellar syndrome. Six had known cancer (three small-cell carcinoma of the lung [SCLC], one metastatic small-cell carcinoma, one small-cell carcinoma of the prostate, and one non-Hodgkin's lymphoma). Six of eight who had neurophysiologic testing, including the three patients without detectable cancer, had coexistent Lambert-Eaton myasthenic syndrome (LEMS). In two of the patients, LEMS was discovered only by neurophysiologic testing. We looked for anti-Purkinje cell autoantibodies in all patient's sera and in four patients' CSF. We also looked for autoantibodies to voltage-gated calcium channels (VGCCs) in seven patients' sera and two patients' CSF, using the 125I-omega-conotoxin radioimmunoassay. We were unable to detect anti-Purkinje cell autoantibodies in any patients' serum or CSF. However, there were raised titers of anti-VGCC autoantibodies in five of seven patients' serum, including one patient with SCLC who did not have LEMS, and in the CSF of one of two patients. We conclude that the frequency of presentation of a pancerebellar syndrome with LEMS is higher than expected by chance and is usually associated with cancer. In some of these patients, LEMS may be clinically occult. The presence of LEMS and raised titers of anti-VGCC autoantibodies in some patients with subacute cerebellar degeneration is suggestive of an autoimmune etiology even though anti-Purkinje cell antibodies could not be detected. Anti-VGCC autoantibodies are not confined to LEMS. They may be found at high titer in CSF as well as serum.

Cerebral aneurysm in relapsing polychondritis

A 51-year-old woman with relapsing polychondritis involving auricular and nasal cartilage, hearing loss, vasculitic skin lesions and a cerebral aneurysm of the posterior cerebral artery is described. Cerebral aneurysm is a rare manifestation of relapsing polychondritis which to our knowledge has not yet been described.

[Systematic lupus erythematosus and pregnancy]

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects primarily women of childbearing age. 20-30 years ago it was common belief that SLE is exacerbated during pregnancy. Recent studies, however, could not support this notion. The likelihood of an increase in clinical activity of SLE is similar during pregnancy and in nonpregnant patients. It correlates directly with the activity of disease at the time of conception. The pregnancy outcome in patients with SLE has improved considerably in recent years. The frequency of fetal loss, however, still remains higher in SLE patients than in healthy women. In most of the cases fetal loss is due to habitual abortions, intrauterine death and premature labors. The main reasons are anti-phospholipid antibodies and the activity of SLE at the onset of pregnancy, respectively during the pregnancy. For monitoring disease activity and especially for distinguishing between the development of eclampsia and exacerbation of SLE, periodic determinations of complement proteins CH50, C3, C4 and C3d are helpful. A prophylactic therapy e.g. with prednisone in pregnant SLE patients is not justified. However, when SLE is exacerbating immunosuppressive therapy with prednisone and, if needed in combination with azathioprine, should be administered. In cases with high antiphospholipid antibody titers and prior fetal loss a treatment with low-dose acetylsalicylic acid can be considered.

Characterization of the epidermis from barley primary leaves : II. The role of the epidermis in ion compartmentation

The cation and anion distribution between the epidermis and mesophyll of primary leaves of 10-d-old barley (Hordeum vulgare L.) seedlings was studied in relation to growth conditions. A new method was employed to isolate epidermal protoplasts. The following observations were made: (i) Under standard hydroponic growth conditions, K(+) was the dominant cation and NO 3 (3-) the predominant anion, both in epidermal and mesophyll protoplasts. (ii) Levels of Cl(-) and particularly of Ca(2+) were specifically increased in the epidermis when growth conditions stimulated uptake of these ions into the plants. (iii) Epidermal PO 4 (3-) was maintained at a very low level even in the presence of 50 mM phosphate in the rooting medium, whereas the phosphate concentration in the mesophyll was high, with phosphate being accumulated in the mesophyll vacuoles. (iv) Sulphate and NO 3 (-) accumulated to a similar degree in the mesophyll and the epidermis when K2SO4 or KNO3 in the rooting medium caused salt stress to the plants. (v) Epidermal protoplasts took up (35)SO 4 (2-) and (36)Cl(-) from the surrounding medium. A comparison of the uptake rates indicates that specific ion deposition into the epidermis may partially be the consequence of differential uptake of ions from the transpiration stream. The results indicate an important function of the epidermis for ion compartmentation in barley leaves.

The synaptic vesicle protein synaptotagmin associates with calcium channels and is a putative Lambert-Eaton myasthenic syndrome antigen

Immunoglobulin G fractions from patients with Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease of neuromuscular transmission, immunoprecipitate 125I-labeled omega-conotoxin GVIA-labeled calcium channels solubilized from rat brain. A 58-kDa antigen was detected by probing Western blots of partially purified calcium channels with LEMS plasma and IgG and was shown to be the relevant antigen in omega-conotoxin receptor immunoprecipitation. Monoclonal antibody 1D12, produced by immunizing mice with synaptic membranes, has properties similar to these autoimmune IgGs in both immunoprecipitation and Western blotting assays. 1D12 antigen was purified by immunoaffinity chromatography and shown to bind LEMS IgG. The antigen was identified by screening a rat brain cDNA library with 1D12 and was found to have strong homology to the synaptic vesicle membrane protein synaptotagmin. Our results indicate therefore that these antibodies immunoprecipitate omega-conotoxin receptors by binding to synaptotagmin that is associated with calcium channels. We suggest that the interaction between synaptotagmin and the voltage-gated calcium channel plays a role in docking synaptic vesicles at the plasma membrane prior to rapid neurotransmitter release and that autoantibody binding to a synaptotagmin-calcium-channel complex may be involved in the etiology of LEMS.

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.

Search for cross-reactive idiotypes on monoclonal and myasthenia gravis acetylcholine receptor antibodies

Myasthenia gravis patients have serum anti-acetylcholine receptor antibodies that compete with monoclonal antibodies for binding to epitopes on the human acetylcholine receptor. To investigate the presence of shared idiotypes we immunised syngeneic mice with each of ten well-characterised monoclonal antibodies, previously raised against purified human acetylcholine receptor, and tested the polyclonal antisera and seven monoclonal anti-idiotype antibodies, for binding to the antigen-combining site, to framework idiotopes, and by ELISA. The polyclonal sera were mostly directed against antigen-combining site idiotopes and cross-reacted only with monoclonal anti-acetylcholine receptor antibodies that bound to the same region on the acetylcholine receptor. In contrast, five of the seven IgM monoclonal anti-idiotypic antibodies raised, none of which demonstrated antigen-combining site specificity in solution, cross-reacted with mAbs binding to more than one region. None of the antisera showing reactivity with the antigen-combining site inhibited the binding of MG anti-acetylcholine receptor antibody.

MHC gene products and anticardiolipin antibodies in systemic lupus erythematosus results of a multicenter study. SLE Study Group

Anticardiolipin antibodies (aCL) and HLA-DR antigens were determined in 314 central European patients with systemic lupus erythematosus (SLE). Both HLA-DR4 and DR7 were increased in aCL-positive patients, and aCL were significantly associated with DRw53. The association between DRw53 and aCL was also apparent in those 17 patients with SLE and the anticardiolipin syndrome. There was no association between aCL and HLA-DQ or C4 alleles in SLE.

Primary antiphospholipid syndrome (PAPS). Two case reports and therapeutic implications

Antiphospholipid antibodies (aPL) interfere with the coagulation system and can cause thrombosis and other clotting disorders. The combination of recurrent venous thrombosis, arterial embolism and recurrent fetal loss is nowadays considered to be primary antiphospholipid syndrome (PAPS), provided an underlying systemic lupus erythematosus (SLE) has been excluded and aPL have been detected. We report on two patients with PAPs, and show the course of their IgG- and IgM-anticardiolipin antibody (aCL) titers during immunosuppressive therapy with prednisone and azathioprine or cyclophosphamide. Over a period of 18 months this therapy was effective in preventing relapses of thrombo-embolism and other complications. Therapy with cyclophosphamide resulted in normalization of the aCL titers in one of the two reported cases. Azathioprine treatment reduced the aCL titer in the other patient, without fully normalizing it. Based on our observation, we propose to treat PAPS-associated severe and recurrent thrombo-embolic complications by aggressive immunosuppression, including azathioprine and cyclophosphamide.

[Kidney function in therapy with non-steroidal antiphlogistic drugs. A double-blind cross-over study with diclofenac, indomethacin and piroxicam]

The effect of piroxicam (1 x 20 mg daily), diclofenac (2 x 50 mg daily) and indomethacin (3 x 25 mg daily) on renal function was compared in a double-blind cross-over study of 33 patients with various rheumatologic diseases. Individuals with preexisting renal impairment were excluded. In 16 patients piroxicam was compared with diclofenac. In another group of 17 patients piroxicam was compared with indomethacin. Each drug was given for 28 days. The mean inhibition of renal prostaglandin E2 by the three drugs was comparable. There was no significant alteration of the renal function parameters in any of the drugs. These results confirm that nonsteroidal antiinflammatory drugs with short (diclofenac, indomethacin) but also with long half life (piroxicam) do not decrease renal function in individuals without renal impairment.

Hetero- and homozygosity of MHC class II gene products in systemic lupus erythematosus. The Members of the Deutsche Multizentrische SLE-Studie

An analysis of HLA class II antigens in 356 white patients with systemic lupus erythematosus (SLE) showed that all HLA-DR and -DQ homozygous and heterozygous combinations appear with frequencies expected from the observed gene frequencies. HLA-DR2 and HLA-DR3 gene frequencies were both increased in SLE, as were the odds ratios of all DR2 and DR3 hetero- and homozygous combinations. HLA-DR2/C4AQ0 heterozygotes were also not increased over expected values. Therefore, gene complementation at MHC loci does not contribute to susceptibility to SLE, but rather one or two MHC allele(s) in linkage with HLA-DR2 and HLA-DR3.

Seronegative myasthenia gravis: a plasma factor inhibiting agonist-induced acetylcholine receptor function copurifies with IgM

Anti-acetylcholine receptor antibodies cannot be detected by standard radioimmunoassay in 10 to 15% of patients with generalized myasthenia gravis (seronegative myasthenia gravis). We investigated the effect of seronegative myasthenia gravis plasma on 22Na+ flux through acetylcholine receptors and voltage-gated sodium channels in the human rhabdomyosarcoma cell line, TE671. Fourteen of 19 seronegative MG plasmas inhibited acetylcholine receptor 22Na+ flux; none inhibited voltage-gated sodium channel flux. The inhibitory activity was found in the IgG-depleted fraction, and copurified with IgM after gel-filtration chromatography. Inhibitory activity was absent from the plasma of 8 healthy control subjects and of 6 patients with the Lambert-Eaton myasthenic syndrome, but was present in the IgG-depleted plasma fraction of 4 of 6 seropositive patients with myasthenia gravis and all 5 patients with demyelinating polyneuropathy. We conclude that a low-affinity serum factor, probably an IgM antibody, found in a high proportion in patients with seronegative and those with seropositive myasthenia gravis may contribute to the muscle weakness in myasthenia gravis, but its role in these and other neuroimmunological disorders requires further investigation.

Low dose methotrexate therapy for rheumatoid arthritis complicated by pancytopenia and Pneumocystis carinii pneumonia

In a patient with rheumatoid arthritis pancytopenia and Pneumocystis carinii pneumonia occurred during low dose methotrexate therapy. This case emphasizes the potential development of opportunistic infections even with low dose methotrexate. Pneumocystis carinii pneumonia resembles methotrexate induced pneumonitis. Therefore opportunistic infections should be considered before a definite diagnosis of methotrexate induced pneumonitis is made.

Autoimmune aetiology for acquired neuromyotonia (Isaacs' syndrome)

Neuromyotonia is a rare disorder of unknown cause in which hyperexcitability of peripheral motor nerves leads to incapacitating muscle twitching, cramps, and weakness. We investigated an antibody-mediated mechanism for neuromyotonia in a 24-year-old man with a 7-year history of severe disease unresponsive to pharmacological treatment. Two periods of plasma exchange each produced almost complete disappearance of symptoms for 2-3 weeks, and a highly significant decrease in recorded neuromyotonic discharges. Injection of the patient's plasma or purified IgG into mice significantly enhanced in-vitro resistance to d-tubocurarine at the neuromuscular junction of phrenic nerve-diaphragm preparations. This finding suggests that an increase in neurotransmitter release might result from an antibody-mediated reduction in the number of functional potassium channels that normally regulate nerve excitability. The demonstration of pathogenic IgG autoantibodies in acquired neuromyotonia suggests that immunosuppressive treatment may be helpful in severe cases.

[Chronic immunoproliferative syndromes]

Immunoproliferative syndromes are etiologically unclear, rare diseases which involve polyclonal B- and/or T-cell proliferations and frequently develop into malignant non-Hodgkin-lymphoma. Typically, these diseases are characterized by lymphadenopathies, hepatosplenomegaly, general fatigue and autoimmune phenomena. Here we briefly outline 6 syndromes, two of which--the "pluripotential chronic immunoproliferative syndrome" (CPIS) and the "angioimmunoblastic lymphadenopathy" (AILD)--are discussed in more detail. We favor the notion that CPIS is a variant form of AILD clinically dominated by severe autoimmune hemolytic anemia. Both diseases share the high frequency of anti-cytoskeleton autoantibodies.

Calcium channel autoantibodies in the Lambert-Eaton myasthenic syndrome

We have tested 36 patients with the Lambert-Eaton myasthenic syndrome for serum antibodies to voltage-gated calcium channels by using an immunoprecipitation assay with [125I] omega-conotoxin-labeled voltage-gated calcium channels extracted from a human neuroblastoma cell line, SKN-SH. Forty-four percent of these patients had significant levels of antibody (30-1,466 pM) compared with healthy control individuals (less than 15 pM). The incidence of positive sera in patients without associated small cell lung carcinoma (61%) was greater than in those patients with small cell lung carcinoma (28%). Results correlated strongly with results obtained using voltage-gated calcium channels extracted from the small cell lung carcinoma line, MAR5. Anti-voltage-gated calcium channel antibody titers did not correlate with disease severity across individuals, but longitudinal studies in 2 patients receiving immunosuppressive therapy showed a clear inverse relation between antibody titer and an electromyographic index of disease severity. The incidence of positive sera among patients with other neurological disorders was not significant, but 8 of 12 patients with rheumatoid arthritis or systemic lupus erythematosus had raised titers (30-82 pM). We conclude that the antibodies detected in this assay are heterogeneous and that some of them are likely to be implicated in this disorder of neuromuscular transmission. The assay should prove useful as an additional diagnostic aid in patients with Lambert-Eaton myasthenic syndrome.

Automated amplification and sequencing of human mitochondrial DNA

Part of the human mitochondrial D-loop region was amplified by two successive rounds of polymerase chain reaction (PCR) amplification. In the second PCR reaction, nested primers were used, of which one contained the M13-21 universal primer sequence. By using nonequal concentrations of primers in the second amplification, single-stranded DNA was generated. This was then sequenced directly by the diodeoxy chain termination method using dye-labelled universal sequencing primers in conjunction with a fluorescence-based DNA sequencer. This enabled a 403-base-pair hypervariable segment of the D-loop region to be readily sequenced in a single reaction. This paper describes a protocol which enables mitochondrial sequence information to be generated rapidly and automatically. It is likely to be of importance in forensic analysis where the DNA is too degraded or of insufficient quantity to be analysed by other techniques.

[Fetal complete heart block with myocarditis and maternal SS-A-/AA-B/antibodies]

We report on a newborn with fetal acquired heart block (CHB). CHB is a rare, irreversible defect, commonly occurring in conjunction with myocarditis in the neonatal lupus syndrome. Development of CHB is strongly associated with maternal anti-SS-A(Ro)/SS-B(La) antibodies. Intrauterine therapy of CHB is not possible. Concomitant myocarditis, however, can be treated effectively with dexamethasone. Mothers with an elevated risk of fetal CHB can be identified by their history (underlying systemic connective tissue disease, previous pregnancies with CHB), an immunogenetic predisposition (HLA-DR3) and analysis of the SS-A/SS-B antibody pattern. In these pregnancies prevention of CHB with plasmapheresis plus dexamethasone during pregnancy may be possible.

[Scintigraphy using 111In-labeled antimyosin in Churg-Strauss vasculitis with myocardial involvement]

A case of Churg-Strauss vasculitis in a young woman is reported. Diagnosis was confirmed by muscle biopsy. Affection of lungs, kidneys and skin was evident. In addition, myocarditis was suspected on clinical evidence. A highly positive scintigraphy with 111In-antimyosin enabled diagnosis and assessment of damage to the myocytes. With a heart-to-lung ratio of 3.0 the accumulated activity in the myocardium was higher than usually found in myocarditis. This finding supports the hypothesis of an additional ischemic necrosis.

Covalent interaction of 3,3'-dichlorobenzidine with hepatic lipids. Enzymic basis and stability of the adducts

Administration of a single oral dose (20 mg/kg) of [U-14C]3,3'-dichlorobenzidine to rats resulted in the in vivo covalent binding of the compound to hepatic lipids. More than 70% of the lipid-3,3'-dichlorobenzidine adducts were accounted for in microsomes. Loss of the lipid-bound 3,3'-dichlorobenzidine residues from either total liver or endoplasmic reticulum occurred in at least two phases--an initial fast phase and a terminal slow phase. In vitro studies with hepatic microsomes in the presence of antibodies to specific P450 isozymes and chemical inhibitors to determine the enzymes that activate 3,3'-dichlorobenzidine to the lipid-binding derivative(s) implicated cytochrome P450d. The 3,3'-dichlorobenzidine-bound microsomal lipids were not mutagenic to Salmonella TA98 in the Ames test. The results suggest that adduct formation between 3,3'-dichlorobenzidine and membrane lipids may provide a measure of 3,3'-dichlorobenzidine activation. It is speculated that covalent interaction of the compound with membrane lipids may modify cellular processes, leading to either enhancement or attenuation of carcinogenesis by the chemical.

[The HLA system and rheumatoid arthritis]

Recent developments in molecular biology allow a more detailed description of and insight into the interaction between T-cell receptor, antigen/peptide, and MHC gene products. These advances also provide a better approach to understanding the molecular genetics of susceptibility to certain diseases. This review tries to interpret MHC structure/function relationships, using rheumatoid arthritis as a paradigm. The following aspects are of special importance: Most likely MHC class-II gene products are directly involved in the pathogenic process and are not only to be considered as "markers". Susceptibility to rheumatoid arthritis is not associated with a single serologically defined HLA-specificity (e.g., HLA-DR4). However, there is substantial evidence that shared functional epitopes on different MHC molecules (e.g., HLA-DR1 and HLA-DR4 subtypes) confer risk for rheumatoid arthritis.

HLA-DR1 and DRw6 association in DR4-negative rheumatoid arthritis patients

This study of 110 seropositive rheumatoid arthritis (RA) patients confirms the significant association of susceptibility to RA with HLA-DR4 specificity (P less than 0.001). The DR1 frequency is elevated in the entire seropositive patient group, reaching marginal significance (P less than 0.025). The DR4-negative patients, however, have a much higher prevalence of DR1 (P less than 0.001). Surprisingly, the DRw6 specificity is significantly increased in the remaining DR4- and DR1-negative patients (P less than 0.01). These results demonstrate that RA is not associated with a single HLA-specificity, but to various degrees with DR4, DR1, and DRw6. These findings, and particularly the newly recognized association with DRw6, support the hypothesis that functionally equivalent shared epitopes or conformations on otherwise distinct MHC molecules may confer risk for developing RA.

[Immunoglobulin and T-cell receptor gene rearrangements in patients with autoimmune diseases]

Immunoglobulin-(Ig-) and T-cell-receptor-(TcR-)gene rearrangements were investigated in peripheral blood lymphocytes (PBL) of patients with various autoimmune disorders. In patients with SLE there was no predominant Ig- or TcR-gene rearrangement. This was also true in patients with a long disease duration and with excessive hypergammaglobulinemia. These results lead us to suggest that B cells are activated polyclonally in these patients. In those cases, where predominantly rearranged Ig- or TcR-genes were found, the autoimmune disorder was associated with a low-grade non-Hodgkin lymphoma (NHL). This coherence of B-cell malignancy and autoimmunity was only found in patients with cryoglobulinemia (KG), cold agglutinin disease (KA), and hemolytic anemia (AIHA).

Further DNA sequence microheterogeneity of the HLA-DR4/Dw13 haplotype group: importance of amino acid position 86 of the DR beta 1 chain for T-cell recognition

Using the polymerase chain reaction we have isolated and sequenced cDNA clones corresponding to the polymorphic first domain of the DR beta 1 chain from the DR4, "Dw13" cell line, JHa. We have found that the JHa DR beta 1 allele differs from previously reported Dw13 alleles by a single amino acid substitution at position 86. The functional relevance of this polymorphism is supported by the reactivity pattern of a T-cell clone, E38. E38 is an alloreactive T-cell clone which reacts with all Dw14 stimulator cells and all Dw13-positive cells tested except the "Dw13"-positive homozygous typing cell line JHa. Inhibition studies with monoclonal antibodies revealed the stimulating determinant to be on DR and not on DQ or DP molecules. These data indicate that position 86 of the DR beta 1 chain can play an important role in the formation of determinants recognized by T cells.

Selective action of myasthenic syndrome antibodies on calcium channels in a rodent neuroblastoma x glioma cell line

1. The effect of Lambert-Eaton myasthenic syndrome (LEMS) immunoglobulin G (IgG) on Ca2+ channels in undifferentiated mouse neuroblastoma x rat glioma hybrid cells (NG 108 15) was studied using the whole-cell patch clamp technique. 2. Sustained inward Ca2+ channel currents were evoked by depolarizing pulses from holding potentials of -80 and -40 mV, and were blocked by 5 microM-nitrendipine (L-type currents). Transient inward Ca2+ channel currents were activated from a holding potential of -80 mV by small depolarizing steps (T-type currents). Noradrenaline (10 microM) was without effect on transient currents. 3. LEMS IgG selectively reduced sustained (L-type) Ca2+ channel current amplitudes evoked from either holding potential used. In the presence of nitrendipine (5 microM), there was no significant effect of LEMS IgG on the remaining transient (T-type) Ca2+ channel current amplitudes. 4. Studies of the potential for maximal inward current indicated that voltage sensitivities of both L- and T-type Ca2+ channel current amplitudes were unaffected by LEMS IgG, whether recorded in the presence or absence of nitrendipine. LEMS IgG had no significant effect on the time-to-peak or decay of Ca2+ channel currents. 5. It is concluded that LEMS IgG acts selectively to cause functional loss of L-type, but not T-type, Ca2+ channels in NG 108 15 cells. Any effect of LEMS IgG on N-type channels (not present in these undifferentiated cells) was not studied here. LEMS IgG also acts at motor nerve terminal Ca2+ channels leading to muscle weakness. Thus antigenic similarities must exist between L-type channels in NG 108 15 cells and Ca2+ channels at motor nerve terminals.

Prognostic factors in childhood ependymomas

Between 1975 and 1989, 45 children with newly diagnosed intracranial ependymomas were treated at the authors' institution. Patients were managed with aggressive surgical resection, followed by postoperative CT or MRI scans to evaluate the extent of resection. Most patients received involved-field radiation therapy, however 10 were treated with craniospinal axis irradiation for disseminated disease, or malignant histology. Beginning in 1983, all patients were also treated with adjuvant chemotherapy with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), vincristine, and cisplatinum. Four patients died in the immediate postoperative period for an operative mortality of 8.8%. The 5-year progression-free survival for the remaining 41 patients was 36%. Tumor location had little effect on survival, as the 5-year PFS for supratentorial tumors was 26%, compared with 40% for the posterior fossa lesions (ns). Neither histologic degree of malignancy, nor use of adjuvant chemotherapy impacted on survival. The extent of surgical resection, as determined by operative reports and postoperative imaging studies, was a major determinant of outcome, as patients with total or near-total resections experienced a 5-year PFS of 60%, compared with 21% for children with partial resection or biopsy (p less than 0.01). It is concluded that the use of adjuvant chemotherapy with CCNU, vincristine, and cisplatinum does not improve progression-free survival in childhood ependymoma, and that the extent of surgical resection is a major determinant of outcome in this disease.