High-dose intravenous immunoglobulin exerts its beneficial effect in patients with dermatomyositis by blocking endomysial deposition of activated complement fragments

In patients with dermatomyositis (DM) the earliest lesion is microvasculopathy mediated by deposition of C5b-C9 membranolytic attack complex (MAC) on intramuscular capillaries. This leads sequentially to muscle ischemia, necrosis of muscle fibers, and muscle weakness. High-dose intravenous immunoglobulin (IVIG), which can modulate complement-dependent tissue damage in animal models, has been shown to be effective in the treatment of patients with DM. We used an in vitro C3 uptake assay to examine 55 coded sera from 13 patients with DM and 5 patients with other non-complement-mediated neuromuscular diseases, before and after treatment with IVIG or placebo. Patients with active DM had a significantly higher baseline C3 uptake compared with the others (geometric mean 12,190 vs 3,090 cpm). Post-IVIG but not post-placebo sera inhibited the C3 uptake, without depleting the complement components, by 70.6-93.4%. The maximum inhibition of C3 uptake occurred within hours after IVIG infusion, started to rebound 2 d later, and reached pretreatment levels after 30 d. The serum levels of SC5b-9 complex production were high at baseline but normalized after IVIG therapy. Repeat biopsies from muscles of improved patients showed disappearance of C3b NEO and MAC deposits from the endomysial capillaries and restoration of the capillary network. We conclude that IVIG exerts its beneficial clinical effect by intercepting the assembly and deposition of MAC on the endomysial capillaries through the formation of complexes between the infused immunoglobulins and C3b, thereby preventing the incorporation of activated C3 molecules into C5 convertase. These findings provide the first serological and in situ evidence that IVIG modulates complement attack in a human disease.

Current treatment of the inflammatory myopathies

Among the main concerns regarding the current therapy for the inflammatory myopathies are a lack of adequate controlled trials, a lack of objective means to reliably measure muscle strength, lack of natural history data, consideration of polymyositis, dermatomyositis, and inclusion-body myositis as a homogeneous group of inflammatory myopathies, and reliance on nonspecific markers for determining prognosis and assessing response to therapies. Prednisone remains the drug of choice in treating these disorders, although a controlled trial has never been undertaken to study its efficacy. Among the steroid-sparing agents, azathioprine, methotrexate, cyclosporine, and chlorambucil are used with invariably low to moderate success. There are no results of controlled trials to indicate whether one of these drugs is superior to another. Intravenous immunoglobulin, which is very expensive, was shown in a controlled trial to be effective in steroid-resistant dermatomyositis not only in dramatically improving muscle strength and skin rash but also in resolving the underlying immunopathology. Controlled trials of intravenous immunoglobulin in patients with polymyositis and inclusion-body myositis are under way. Inclusion-body myositis has emerged as a common inflammatory myopathy that is predictably disabling and resistant to most therapies.

A personality profile of patients diagnosed with post-polio syndrome

Post-polio syndrome (PPS) refers to the late development of new neuromuscular symptoms in previously stable poliomyelitis patients. Whether psychological disturbance plays a role in the manifestation of symptoms in these patients is unclear. We examined 22 patients fulfilling the clinical criteria for PPS with the Minnesota Multiphasic Personality Inventory-II (MMPI-II), Beck Depression Inventory, Spielberger State-Trait Anxiety Scales, Chapman and Chapman Psychosis-Proneness Scales, Fatigue Scales, a neurobehavioral rating scale, and Cognitive Symptoms Self-Report Scales. The overwhelming majority of scale scores were within normal limits, and there was no indication that psychopathologic symptoms were associated with the development or severity of new muscle weakness in PPS patients. Women with PPS had significantly more somatic complaints, but were less socially isolated than men with PPS. This study confirms that the development or severity of new muscle weakness in carefully diagnosed PPS patients is not due to, or influenced by, underlying psychopathology.

Polymyositis in patients infected with human T-cell leukemia virus type I: the role of the virus in the cause of the disease

To investigate the mechanism of polymyositis in human T-cell leukemia virus type I (HTLV-I) infection, we studied 6 HTLV-I-positive patients, 3 with polymyositis and 3 with adult T-cell leukemia but without clinical signs of muscle disease, by (a) quantitative single or double immunocytochemistry on serial 4-microns-thick muscle biopsy sections using antibodies to lymphocyte subsets, major histocompatibility complex (MHC) antigens, and HTLV-I proteins; (b) polymerase chain reaction using HTLV-I primers in the RNA and DNA extracted from 50 micrograms of muscle tissue or from serial 5-microns-thick fresh-frozen tissue sections; and (c) cocultures of the patients' HTLV-I-positive peripheral blood lymphocytes with their homologous muscles searching for replication of HTLV-I within the myotubes. In the muscle of patients with HTLV-I-associated myopathy, the predominant endomysial cells surrounding healthy muscle fibers were CD8+ cells followed by CD4+ cells and macrophages. MHC-I antigens were ubiquitous in the muscles of all 6 patients, even in those without endomysial inflammation. HTLV-I sequences were amplified from the whole muscle biopsy specimens but the cells harboring viral antigens were rare endomysial macrophages and not muscle fibers. Although HTLV-I sequences were amplified from all the patients' peripheral blood lymphocytes, these cells did not exert myotoxicity or resulted in viral replication in cocultures with their homologous myotubes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of high-dose intravenous immunoglobulin on amyotrophic lateral sclerosis and multifocal motor neuropathy

OBJECTIVE

To determine if high-dose intravenous immunoglobulin therapy is effective in improving muscle strength or in arresting the pace of disease progression in patients with rapidly progressive amyotrophic lateral sclerosis.

DESIGN

An open-label pilot study of intravenous infusions of high-dose immunoglobulin administered once a month for 3 months in nine patients with classic amyotrophic lateral sclerosis. Selected patients had a rapidly progressive course with signs of worsening noticeably evident every 6 weeks prior to therapy. A patient with multifocal motor neuropathy with conduction block that presented as a lower motor neuron syndrome was concurrently treated to document the efficacy of the same preparation of immunoglobulin in a potentially treatable disease that simulates lower motor neuron syndrome. The efficacy of high-dose intravenous immunoglobulin infusions was assessed by objective measurement of maximum voluntary isometric contraction in all muscle groups of two limbs before and after therapy.

SETTING

The Clinical Center of the National Institutes of Health, Bethesda, Md.

RESULTS

All patients with amyotrophic lateral sclerosis worsened during the study. By the end of the third month, their mean total muscle scores (megascores) had declined by 71.2 points, from a mean of 369.7 (range, 200 to 605) to 298.5 (range, 130 to 552) points. The pace of progression did not change during the 4-month observation period. In contrast, the patient with multifocal motor neuropathy responded to intravenous immunoglobulin therapy and increased his megascores by 146 points after 3 months. The GM1 antibody titers were normal in all the patients.

CONCLUSIONS

High-dose intravenous immunoglobulin, a prohibitively expensive drug, has no apparent therapeutic role in improving the symptoms or arresting the pace of progression in patients with amyotrophic lateral sclerosis. In contrast, multifocal motor neuropathy is an immunopathologically different disease that responds to intravenous immunoglobulin therapy.

Aseptic meningitis associated with high-dose intravenous immunoglobulin therapy: frequency and risk factors

OBJECTIVE

Intravenous immunoglobulin is widely used to treat various autoimmune disorders. After observing instances of aseptic meningitis in treated patients, we studied the frequency and associated risk factors for aseptic meningitis in patients treated with high-dose intravenous immunoglobulin.

DESIGN

Retrospective analysis of a prospective cohort study.

SETTING

Tertiary research referral center.

PATIENTS

54 consecutive patients with various immune-related neuromuscular diseases participating in ongoing therapeutic trials of high-dose (2 g/kg) intravenous immunoglobulin.

MEASUREMENTS

Analysis of patient records for evidence of aseptic meningitis, associated risk factors, penetration of serum IgG into the cerebrospinal fluid, and clearance of cerebrospinal fluid IgG.

RESULTS

Of 54 patients, 6 (11%; 95% CI, 4% to 23%) developed aseptic meningitis within 24 hours after completion of the infusions. Symptoms, lasting 3 to 5 days, included severe headache, meningismus, photophobia, and fever. Cerebrospinal fluid showed pleocytosis in 4 patients (leukocyte count as high as 1169 x 10(6)/L in one patient), eosinophilia in 3 patients, and IgG elevation in all patients (as great as 7 times the upper limit of normal in one patient). Repeat cerebrospinal fluid and serum studies after 24 hours showed a 46% cerebrospinal fluid IgG clearance compared with an 11% clearance of serum IgG in one patient. Cerebrospinal fluid cultures were negative. Aseptic meningitis developed in 4 of 8 patients (50%; CI, 16% to 84%) with a history of migraine but in only 2 of 46 (4%; CI, 0.5% to 15%) patients without such a history (P = 0.003). Aseptic meningitis recurred in patients who had migraine despite the use of different commercial intravenous immunoglobulin preparations and slower rates of infusion.

CONCLUSION

Aseptic meningitis develops in patients receiving high-dose intravenous immunoglobulin therapy. Patients with a history of migraine are more likely to develop aseptic meningitis while receiving intravenous immunoglobulin therapy, regardless of the type of commercial preparation or the infusion rate. Possible inciting factors include the IgG itself, various stabilizing products within each of the preparations, cytokine release triggered by the therapy, or cerebrovascular sensitivity in migraineurs.

Effect of L-carnitine on the zidovudine-induced destruction of human myotubes. Part I: L-carnitine prevents the myotoxicity of AZT in vitro

BACKGROUND

Zidovudine (AZT) as used in the treatment of AIDS, causes a mitochondrial myopathy characterized by depletion of mitochondrial DNA, enzymatic defects in the respiratory chain system, and accumulation of lipid droplets. Most of these changes are also seen in normal human myotubes treated with AZT. Because L-carnitine plays a major role in the transport of long chain fatty acids across the inner mitochondrial membrane and facilitates the beta-oxidation of fatty acids, we examined the effect of L-carnitine in preventing the destructive effect of AZT on the mitochondria and the myotubes of human muscle in tissue culture.

EXPERIMENTAL DESIGN

Myotubes, prepared from human muscle biopsies, were exposed to various concentrations of AZT for up to 3 weeks. One-third of the flasks were treated with AZT alone, another third with AZT plus L-carnitine and another third were untreated. The cultures were evaluated with: (a) immunocytochemistry counting the number of myotubes stained with antibodies to Leu-19; (b) enzyme histochemistry for NADH reaction and oil-red-O stain to assess mitochondrial enzymatic activity and lipid droplet accumulation; and (c) electron microscopy counting all the organelles within representative sections of the myotubes, at x24,000, and calculating the volumetric density of each organelle/unit volume of tissue.

RESULTS

AZT, at concentrations 250 microM and above, caused depopulation of the Leu-19-positive myotubes, destructive changes in the mitochondria consisting of swelling, lamellar inclusions and multiple concentric cristae, accumulation of lipid droplets, and increase lysosomes. L-Carnitine increased the number of Leu-19-positive myotubes from 3.4 +/- 0.6 to 9.4 +/- 1.2, preserved the morphology of the mitochondria, increased their volumetric density from 2.5 +/- 0.4 to 6.0 +/- 0.7, and reduced the volumetric density of the lipid droplets from 12.2 +/- 4.9 to 1.4 +/- 0.7 and of the lysosomes from 15.6 +/- 3.6 to 3.9 +/- 1.4 (p < 0.001).

CONCLUSIONS

L-Carnitine, used concurrently with AZT, prevents the human myotubes from the AZT-associated destruction, preserves the structure and volume of mitochondria and prevents the accumulation of lipids. The findings may have potential clinical implications in preventing the myotoxicity of AZT in patients with AIDS.

The alpha beta T-cell receptor repertoire in inclusion body myositis: diverse patterns of gene expression by muscle-infiltrating lymphocytes

Inclusion body myositis (IBM) is one member of a group of disorders known as idiopathic inflammatory myopathies (IIM) in which autoreactive T cells directed against muscle are thought to play a primary role in disease pathogenesis. We have utilized the polymerase chain reaction to determine the pattern of alpha beta T-cell receptor (TCR) variable (V) gene expression in muscle biopsies from 13 IBM patients. In the majority of biopsies, we detected oligoclonal patterns of TCR V gene expression by muscle-infiltrating lymphocytes; an average of six out of the 22 TCR V alpha gene families surveyed and seven out of 24 TCR V beta gene families surveyed were detected per biopsy. While no TCR V alpha gene families were over-represented in our survey, TCR V beta 3 and V beta 6 gene usage was a prominent feature of IBM muscle biopsies. TCR gene expression was characterized further by analysing the junctional sequence composition of both V beta 3 and V beta 6 clones from muscle biopsies of the IBM patients. A large number of structurally diverse V beta 3 and V beta 6 clonotypes were identified from these patients demonstrating a polyclonal pattern of T cell infiltration. These data, while describing prominent TCR V beta 3 and V beta 6 gene detection, do not suggest that a common antigen-driven T-cell response promotes chronic inflammation in muscle of IBM patients.

Neuroimmunotherapy: a practical approach to the treatment of immune-mediated neurologic diseases

Immunosuppressive drugs and immunomodulating procedures can improve the quality of life in patients with immune-related neurologic diseases, or even be life saving, if properly used to avoid deleterious or irreversible adverse effects. For the successful use of these drugs or procedures, the treating physician must be familiar and comfortable with the drugs' mode of action and consider some important principles: 1. The diagnosis must be secure before starting therapy. 2. It is essential to have a basic understanding of the immunologic dysfunction that is amenable to immunotherapy. 3. The goals and the expectations of therapy must be defined, and the risk/benefit ratio of the drugs or procedures must be well understood. 4. Improvement must be based on objective measurements of muscle strength and a beneficial change in activities of daily living, and not solely on a change in the laboratory test values. 5. The limitations of therapy and the time suitable for starting or stopping a drug should be clear to both the therapist and the patient. 6. The selection of a drug or procedure should be guided on the basis of current knowledge, preferably established in controlled trials. 7. Every effort must be made to prevent the development of adverse effects and to determine the lowest dose of a medication that controls the disease. 8. Drug interactions that can cause adverse effects and conditions that can worsen a disease must be avoided.

How to diagnose and treat the inflammatory myopathies

The inflammatory myopathies include 3 distinct entities, PM, DM, and IBM. These diseases differ clinically, immunopathologically, and in their response to therapies. Although DM and IBM are easy to diagnose on the basis of characteristic clinicopathologic findings, PM still remains a diagnosis of exclusion. A T cell-mediated cytotoxic process in PM and IBM and a complement-mediated microangiopathy in DM, along with the various serologic markers of autoimmunity, are the hallmarks of the underlying autoimmune processes in these groups. Although in uncontrolled studies PM and DM appear to respond to prednisone and immunosuppressive drugs to some degree and for some period of time, IBM is resistant to all therapies. Currently, high-dose intravenous immunoglobulin (IVIG) appears to be an encouraging and safe new modality of treatment for some of these conditions when other therapies have failed. In a controlled study, IVIG has been shown to be effective in DM and, in uncontrolled studies, in some patients with PM or IBM.

Zidovudine-induced mitochondrial myopathy is associated with muscle carnitine deficiency and lipid storage

The use of zidovudine (AZT) for the treatment of acquired immunodeficiency syndrome (AIDS) induces a DNA-depleting mitochondrial myopathy, which is histologically characterized by the presence of muscle fibers with "ragged-red"-like features, red-rimmed or empty cracks, granular degeneration, and rods (AZT fibers). Because dysfunctioning muscle mitochondria may lead to defects of beta-oxidation of fatty acids, we examined the degree of neutral fat accumulation and muscle carnitine levels in the muscle biopsy specimens from 21 patients with AZT-induced myopathic symptoms of varying severity. Six patients with no AZT fibers had normal endomyofibrillar lipid deposits and muscle carnitine levels; 7 patients with fewer than 5 AZT fibers per field had a mild (+) to moderate (++) increase in lipid droplets, and reduced muscle carnitine levels (3 patients); and 8 patients with more than 5 AZT fibers had severe muscle changes, a ++ to marked ( ) increase in lipid droplets, and reduced muscle carnitine levels (6 patients). Serial sections showed lipid globules often within "cracks" or vacuoles of the abnormal muscle fibers. We conclude that the muscle mitochondrial impairment caused by AZT results in (1) accumulation of lipid within the muscle fibers owing to poor utilization of long-chain fatty acids, (2) reduction of muscle carnitine levels probably due to decreased carnitine uptake by the muscle, and (3) depletion of energy stores within the muscle fibers. The findings may have potential therapeutic implications in the treatment of AZT-induced myopathic symptoms using oral carnitine supplementation.

Predominant TCR-alpha beta variable and joining gene expression by muscle-infiltrating lymphocytes in the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases in which autoreactive T cells are thought to play a pathogenetic role. We have determined the pattern of TCR-alpha beta gene expression by muscle-infiltrating lymphocytes within clinically and serologically defined groups of IIM patients. We utilized the PCR to study TCR V gene expression in muscle biopsies from nine polymyositis (PM) and eight dermatomyositis (DM) patients, all of whom had autoantibodies directed against histidyl-transfer RNA synthetase (anti-Jo-1 autoantibodies). While the TCR repertoire in DM patients was generally polyclonal, an oligoclonal profile characterized PM patients. Certain V gene families were predominantly expressed; V alpha 1 and V beta 6 gene families were detected in 82 and 91% of PM biopsies, respectively. TCR expression was characterized further by analyzing J gene usage from four PM patients expressing the V beta 6 gene. Sequence analysis of 40 independent recombinants (10 per patient) identified only seven V beta 6 clonotypes and restricted usage of the related J beta 2.1, -2.3, and -2.7 genes. These data, describing predominant TCR V and J gene usage by muscle-infiltrating lymphocytes in myositis patients, suggest that Ag-driven T cell responses may play a primary role in mediating some forms of the IIM.

Predominant TCR-alpha beta variable and joining gene expression by muscle-infiltrating lymphocytes in the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases in which autoreactive T cells are thought to play a pathogenetic role. We have determined the pattern of TCR-alpha beta gene expression by muscle-infiltrating lymphocytes within clinically and serologically defined groups of IIM patients. We utilized the PCR to study TCR V gene expression in muscle biopsies from nine polymyositis (PM) and eight dermatomyositis (DM) patients, all of whom had autoantibodies directed against histidyl-transfer RNA synthetase (anti-Jo-1 autoantibodies). While the TCR repertoire in DM patients was generally polyclonal, an oligoclonal profile characterized PM patients. Certain V gene families were predominantly expressed; V alpha 1 and V beta 6 gene families were detected in 82 and 91% of PM biopsies, respectively. TCR expression was characterized further by analyzing J gene usage from four PM patients expressing the V beta 6 gene. Sequence analysis of 40 independent recombinants (10 per patient) identified only seven V beta 6 clonotypes and restricted usage of the related J beta 2.1, -2.3, and -2.7 genes. These data, describing predominant TCR V and J gene usage by muscle-infiltrating lymphocytes in myositis patients, suggest that Ag-driven T cell responses may play a primary role in mediating some forms of the IIM.

High-dose intravenous immunoglobulin and serum viscosity: risk of precipitating thromboembolic events

High-dose intravenous immunoglobulin (IVIg) can increase blood viscosity in vitro and has been associated with cardiovascular or cerebrovascular thromboembolism. Because thromboembolic events were observed in two (3%) of 65 patients we treated with IVIg, we measured serum viscosity serially in 13 patients (five with amyotrophic lateral sclerosis [ALS], eight with IgM paraproteinemic polyneuropathy) before and immediately after each of three consecutive monthly infusions of IVIg. We correlated changes in viscosity with serial determinations of the total serum IgG, IgM, and IgA before and after each infusion. Serum viscosity increased after IVIg in all the patients by 0.1 to 1.0 centipoise (cp) (mean, 0.55 cp). In three ALS patients and in all the patients with paraproteinemic polyneuropathy, serum viscosity exceeded the upper limit of normal (normal, 1.5 to 1.9 cp) and increased as high as 2.6 cp. The increase in viscosity occurred immediately after completion of the infusion, declined over 1 month, and appeared to correlate best with the serum IgG level, which after the infusions was as high as 6,160 mg/dl (normal, 545 to 1,560 mg/dl). I conclude that IVIg increases serum viscosity and in many patients can cross the symptomatic threshold level. Because increased serum viscosity can impair blood flow and trigger a cardiovascular or cerebrovascular thromboembolic event, IVIg should be used judiciously and with concurrent monitoring of serum viscosity in elderly patients and patients with cryoglobulinemia, monoclonal gammopathies, high lipoproteins, or preexisting vascular disease.

A controlled trial of high-dose intravenous immune globulin infusions as treatment for dermatomyositis

BACKGROUND

Dermatomyositis is a clinically distinct myopathy characterized by rash and a complement-mediated microangiopathy that results in the destruction of muscle fibers. In some patients the condition becomes resistant to therapy and causes severe physical disabilities.

METHODS

We conducted a double-blind, placebo-controlled study of 15 patients (age, 18 to 55 years) with biopsy-proved, treatment-resistant dermatomyositis. The patients continued to receive prednisone (mean daily dose, 25 mg) and were randomly assigned to receive one infusion of immune globulin (2 g per kilogram of body weight) or placebo per month for three months, with the option of crossing over to the alternative therapy for three more months. Clinical response was gauged by assessing muscle strength, neuromuscular symptoms, and changes in the rash. Changes in immune-mediated muscle abnormalities were determined by repeated muscle biopsies.

RESULTS

The eight patients assigned to immune globulin had a significant improvement in sores of muscle strength (P < 0.018) and neuromuscular symptoms (P < 0.035), whereas the seven patients assigned to placebo did not. With crossovers a total of 12 patients received immune globulin. Of these, nine with severe disabilities had a major improvement to nearly normal function. Their mean muscle-strength scores increased from 74.5 to 84.7, and their neuromuscular symptoms improved. Two of the other three patients had mild improvement, and one had no change in his condition. Of 11 placebo-treated patients, none had a major improvement, 3 had mild improvement, 3 had no change in their condition, and 5 had worsening of their condition. Repeated biopsies in five patients of muscles whose strength improved to almost normal showed an increase in muscle-fiber diameter (P < 0.04), an increase in the number and a decrease in the diameter of capillaries (P < 0.01), resolution of complement deposits on capillaries, and a reduction in the expression of intercellular adhesion molecule 1 and major-histocompatibility-complex class I antigens.

CONCLUSIONS

High-dose intravenous immune globulin is a safe and effective treatment for refractory dermatomyositis.

Retroviruses and inflammatory myopathies in humans and primates

The human immunodeficiency virus (HIV), the human T cell lymphotropic virus (HTLV-1), the human foamy retrovirus and the simian immunodeficiency viruses have been associated with the development of an inflammatory myopathy in humans and primates. The myopathy caused by HIV and HTLV-1 is not due to direct infection of the muscle by these viruses, but rather due to an immunopathologic process triggered by the viruses, mediated by autoaggressive CD8+ cells in the context of MHC-class I antigen expression. This has been based on a series of studies utilizing immunocytochemistry, in situ hybridization, polymerase chain reaction, and co-cultivation of human myotubes with the viruses or with HIV-1 and HTLV-1-infected homologous lymphoid cells. Because the clinical, histological and immunological picture of patients with retroviral-associated inflammatory myopathies is identical to that of patients with retroviral-negative inflammatory myopathy, there is a reasonable possibility that retroviruses may be candidate viruses in triggering inflammatory myopathies. In recent years, the antiretroviral drug AZT (Zidovudine), commonly used for the treatment of AIDS, has been shown to cause a distinct mitochondrial myopathy characterized by depletion of the muscle mitochondrial DNA due to AZT's ability to inhibit the gamma-DNA polymerase of the mitochondrial matrix. Distinction of the AZT-myopathy is clinically important because it responds to discontinuation of AZT and to administration of another antiretroviral agent such as ddI or ddC.

Muscle carnitine repletion by long-term carnitine supplementation in nephropathic cystinosis

The renal tubular Fanconi syndrome of children with nephropathic cystinosis causes plasma and muscle carnitine depletion. L-Carnitine replacement therapy for up to 18 mo has previously been shown to normalize plasma but not muscle carnitine levels. We treated six cystinosis patients, aged 1 to 4 y, with a mean dosage of 92 mg L-carnitine/kg/d given every 6 h for an average of 62 mo. Despite fractional excretions of free carnitine ranging from 55 to 108%, plasma-free and total carnitine concentrations were maintained at or above normal levels. At the end of the carnitine replacement period, the six children had muscle-free carnitine values ranging from 16.0 to 28.0 nmol/mg noncollagen protein compared with values of 3.0 to 11.4 for cystinosis children not supplemented with carnitine [normal, 22.7 +/- 5.0 (SD) nmol/mg protein]. Total muscle carnitine values were also normalized by L-carnitine replacement. The monthly increase in total body creatinine production, a measure of muscle mass, was higher (p = 0.036) in children with normal plasma free carnitine concentrations (3.4 +/- 0.9 mg/d) than in children with low plasma free carnitine (2.3 +/- 0.7 mg/d). No serious side effects, such as severe diarrhea, were observed. We conclude that oral L-carnitine replacement can normalize muscle carnitine content in children with cystinosis.

Immune-mediated mechanisms and immune activation of fibroblasts in the pathogenesis of eosinophilia-myalgia syndrome induced by L-tryptophan

To determine the immunopathogenesis of the persistent symptoms of patients with eosinophilia-myalgia syndrome (EMS) induced by L-tryptophan, we performed immunocytochemical studies on 10 muscle and fascia biopsy specimens obtained during the acute disease and the chronic persistent connective tissue sclerosis. A series of monoclonal antibodies was used in a single- or double-immunostaining technique to detect and quantify T-cell subsets, macrophages, major histocompatibility complex antigens, eosinophilic basic protein-positive cells, and resting fibroblasts expressing Thy-I antigen or activated fibroblasts expressing the activation marker F-19. We found inflammatory cells consisting of CD8+ cells (45% +/- 8.9%), T4 cells (36% +/- 10.1%), and macrophages (19% +/- 12%), scattered or perivascularly in the fascia, the perimysium, and the endomysial septae. Only rare granulated or degranulating eosinophils were noted. Many muscle fibers around fascicles or near blood vessels expressed major histocompatibility complex-I antigens. The mean number of fibroblasts in the fascia, the perimysial connective tissue, and the spindle capsule was increased in the EMS patients' specimens compared with the endomysial cells seen in six disease-control muscle biopsy specimens from patients with chronic inflammatory myopathies or dystrophies (P < .01). Up to 70% of the fibroblasts in EMS were activated and up to 30% of them expressed HLA-DR antigen. In the disease controls up to 29% of the fibroblasts were activated but none expressed DR. Repeat muscle biopsy a year later in a patient whose symptoms persisted showed reduced inflammation but an increased number of activated fibroblasts and enhanced DR expression. We conclude that in EMS there is a T-cell-mediated process against components of the extracellular matrix, including fibroblasts, in the fascia and the perimysium that persists even years after the drug is discontinued. Because the fibroblasts are activated and aberrantly express DR antigen, they may be the target cells playing a role in the continuing clinical and histologic signs of tissue sclerosis.

Missense mutations in the beta-myosin heavy-chain gene cause central core disease in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an important cause of sudden death in apparently healthy young individuals. In less than half of kindreds with HCM, the disease is linked to the beta-myosin heavy-chain gene locus (MYH7). We have recently described two missense MYH7 gene mutations [Arg-403 to Gln (R403Q) and Leu-908 to Val (L908V)] and found that the mutant message is present in skeletal muscle soleus) and that the mutant beta-myosin obtained from soleus muscle has abnormal in vitro motility activity. Having identified a second kindred with the R403Q mutation, and 3 other kindreds with two additional mutations (G741R and G256E), we performed histochemical analysis of soleus muscle biopsies from 25 HCM patients with one of these four mutations. Light microscopic examination of the NADH-stained biopsies revealed the presence of central core disease (CCD) of skeletal muscle, a rare autosomal dominant nonprogressive myopathy characterized by a predominance of type I "slow" fibers and an absence of mitochondria in the center of many type I fibers. CCD was present in 10 of 13 patients with the L908V mutation, 5 of 8 patients with the R403Q mutation, 1 of 3 patients with the G741R mutation, and 1 patient with the G256E mutation. Mild-to-moderate myopathic changes with muscle fiber hypertrophy were present in 16 patients. Notably, CCD was present in 2 adults and 3 children with the L908V mutation who did not have cardiac hypertrophy. In contrast, soleus muscle samples from 5 patients from 4 kindreds in which HCM was not linked to the MYH7 locus showed no myopathy or CCD. Soleus muscle biopsies from 5 control subjects also showed normal histology. This work demonstrates that (i) MYH7-associated HCM is often a disease of striated muscle but with predominant cardiac involvement and (ii) a subset of HCM patients with MYH7 gene missense mutations have CCD.

Treatment of inclusion-body myositis with high-dose intravenous immunoglobulin

We report the treatment of four patients with inclusion-body myositis (IBM) and severe slowly progressive weakness using high-dose intravenous immunoglobulin (IVIg). After two monthly infusions, the strength of the proximal and less atrophic muscle groups improved or normalized in three of the four patients. The improvement lasted from 2 to 4 months. Intravenous immunoglobulin is the first treatment modality to improve the strength of some muscles in patients with this disabling inflammatory myopathy. In view of the high cost of IVIg, the unexpected but encouraging results from this pilot study warrant a controlled trial.

Search for HIV proviral DNA and amplified sequences in the muscle biopsies of patients with HIV polymyositis

We searched for the presence of human immunodeficiency virus (HIV) in fresh-frozen muscle biopsy specimens from 10 patients with HIV-associated polymyositis (HIV-PM) using (a) 35S-labeled HIV-RNA transcript of the virus and in situ hybridization, and (b) polymerase chain reaction and slot-blot hybridization utilizing primers amplifying sequences from the gag and pol genes of the HIV genome. With in situ hybridization, positive signals were detected in sparse lymphoid cells surrounding the muscle fibers, but not within the muscle fibers, in up to two consecutive sections in 6 of the 10 specimens. By the polymerase chain reaction, amplified HIV-specific sequences were noted in 2 specimens, but in only 2 of 8 consecutive sections, implying infection of lymphoid cells rather than muscle fibers. Muscle cultures from six specimens failed to show integrated HIV sequences within the myotubes. We conclude that HIV sequences or transcriptional products are not present within the muscle fibers or the cultured myotubes of patients with HIV-PM. This indicates that: (a) viral replication does not take place within the muscle; (b) integration of HIV proviral genome does not occur within the myonuclei or satellite cells; and (c) HIV-PM does not seem to be due to a persistent infection of the muscle fiber by the virus.