Intravenous immunoglobulin treatment in patients with motor neuron syndromes associated with anti-GM1 antibodies: a double-blind, placebo-controlled study

We studied the effects of intravenous immunoglobulin (IVIg) in 12 patients with motor neuron syndromes associated with high titers of anti-GM1 antibodies. Five of the patients had conduction blocks. The study design was a double-blind, placebo-controlled, crossover trial with IVIg (0.4 g/kg body weight per day injected for 5 consecutive days). We evaluated the patients before and 5, 28, and 56 days after drug administration using a computerized analyzer for muscle strength, the Norris scale for disability, motor nerve conduction velocities for patients with conduction blocks, and measurements of immunologic markers. Compared with placebo, IVIg induced a significant increase in muscle strength only in the patients with conduction blocks.

Neuronal control of MHC class II inducibility in rat astrocytes and microglia

We analysed the inducibility of major histocompatibility complex (MHC) class II molecules of astrocytes and microglia in organotypic hippocampus slice cultures of Lewis rats. Treatment with interferon-gamma (IFN-gamma) resulted in the induction of MHC class II molecules on microglia preferentially in the injured marginal zones of the slice culture, but only sporadically in areas containing intact neuronal architecture. In astrocytes, inducibility of MHC class II molecules was even more strictly controlled. IFN-gamma treatment induced MHC class II expression only in the slice culture zones containing degenerated neurons, and not in the presence of functional neurons. After suppression of spontaneous neuronal activity of the slice culture by the sodium channel blocker tetrodotoxin, MHC class II molecules on astrocytes could be induced by IFN-gamma in areas with intact neuronal architecture, and microglia cells exhibited a higher level of expression. These data suggest that loss of neurons could result in MHC class II inducibility of glial cells, and thus in increased immune reactivity of nervous tissue.

Long term follow up of multifocal motor neuropathy with conduction block under treatment

Eighteen patients (15 men, three women; age range 30 to 71 years, mean 45.8 years) with multifocal motor neuropathy treated with high dose intravenous immunoglobulin (IVIg) were evaluated for nine to 48 months (mean follow up 25.3 months). The median time between onset of multifocal motor neuropathy and treatment was 5.8 years. The dose of IVIg was 0.4 g/day for three to five days. The interval between each treatment was determined for each patient by the evaluation of the effect of the first course. Muscle strength was evaluated by a computerised analyser. Clinical improvement was seen in 12 patients treated with IVIg (67%). Isometric strength increased from 32% to 97% (mean 54.5%) of the initial value. Functional scales corroborated these findings. No clear predictive factors of response to IVIg was found except the presence of high titres of IgM anti-GM1 antibodies. Often, patients needed repeated courses of IVIg to maintain the improvement. In two patients, IVIg infusions were stopped without signs of relapse after one year. Four patients were initially treated with prednisone (1 mg/kg/day), without any clear improvement. Five patients with no response to IVIg or who were IVIg dependent were treated with cyclophosphamide, but only one showed improvement. These results show the long term benefits and safety of IVIg in multifocal motor neuropathy but also the transient effect of this expensive treatment in most patients.

Expression of various isoforms of neural cell adhesive molecules and their highly polysialylated counterparts in diseased human muscles

Antibodies directed against neural cell adhesive molecules (NCAM) and in particular a monoclonal antibody recognizing polysialylated isoforms, were used to characterize the expression of these molecules in normal and diseased human muscles. Normal subjects as well as patients with inflammatory, dystrophic and denervating diseases were examined. By immunohistochemistry the main observations were (1) satellite cells expressed the non-sialylated form of NCAMs; (2) regenerative fibers strikingly expressed NCAMs and their sialylated isoforms both on membranes and in the cytoplasm; (3) in denervated muscles, fibers in atrophic groups and some fibers in acute denervation expressed NCAMs on their membrane but not the highly sialylated form; (4) finally, some fibers in myotonic dystrophy and fibers with rimmed vacuoles also expressed NCAMs. Biochemical approaches, using enzymes such as endoglycosidase N and phosphatidylinositol phospholipase C combined with immunoblot analysis allowed visualization of the nature of the expressed isoforms. We have shown that non activated cells, i.e. satellite cells and denervated fibers do not express polysialylated NCAMs. This post-translational modification may be only observed in activated or regenerating fibers. This would parallel the sequence of NCAM expression occurring in normal myogenic pathways.

Terminal latency index and modified F ratio in distinction of chronic demyelinating neuropathies

OBJECTIVE

To evaluate indexes calculated from standard electrophysiological data in differentiating chronic demyelinating polyneuropathy (CDP).

METHODS

Nerve conduction study of upper limbs was investigated in 19 chronic inflammatory demyelinating polyneuropathy (CIDP) patients, 25 anti-myelin-associated glycoprotein/sulfated glucuronyl paragloboside antibodies (MAG/SGPG) CDP patients, 13 Charcot-Marie-Tooth disease type 1A (CMT1A) patients and 22 controls. Terminal latency index (TLI) was used to compare the wrist-to-thenar muscle segment with the elbow-to-wrist conduction velocity. Modified F ratio (MFR) was used to compare the spinal cord-to-elbow segment latency with that of the wrist-to-thenar muscle segment.

RESULTS

Compared with controls, TLI was decreased in 21 anti-MAG/SGPG CDP patients while MFR was either decreased or was normal. In 16 CIDP patients, MFR was increased while TLI was either normal or increased. In CMT1A both TLI and MFR were in normal ranges. The sensitivity of MFR as a supportive finding in CIDP was found to be 84% and its specificity 89%. The sensitivity of TLI as a mean of diagnosis of anti-MAG/SGPG CDP was found to be 93% and its specificity 90%.

CONCLUSIONS

The results of TLI and MFR facilitates distinction between different types of CDP. In CIDP, MFR was significantly higher and TLI showed no change; in the anti-MAG/SGPG CDP, TLI and MFR were significantly lower; in CMT1A, TLI and MFR showed no change in comparison with the controls.

HLA-E is the only class I gene that escapes CpG methylation and is transcriptionally active in the trophoblast-derived human cell line JAR

Polymorphic as well as HLA-F and -G genes are repressed in the human cell line JAR, derived from a tumor of trophoblast origin. By contrast, the HLA-E gene as well as the non-HLA novel coding-sequence, R1, located 5' to HLA-E, both remain transcriptionally active. We first demonstrated the role of DNA methylation in the repression of class I genes (except HLA-E) in JAR by the use of the 5-Azacytidine demethylating agent. Following treatment, JAR clones reexpressed polymorphic class I transcripts and cell surface alpha chains. Using methylation-sensitive rare cutter enzymes on JAR genomic DNA, followed by classical or pulse field gel electrophoresis and hybridization with HLA locus-specific probes, we found methylated CpG islands in the 5' region of all class I genes, except for HLA-E. These results, establishing an inverse relationship between states of methylation and transcriptional activity within the MHC class I chromosomal region in JAR, and the observations that the HLA-E and R1 genes were ubiquitously expressed, suggest that the HLA-E chromosomal domain might have functional importance including the presence of housekeeping genes.

Evidence for autoimmune antibodies directed against embryonic neural cell adhesion molecules (N-CAM) in patients with group B meningitis

Human brain tissue shares alpha 2-8 linked polymers of neuraminic acid with the carbohydrates expressed on the capsule of group B Neisseria meningitidis bacteria (Finne et al. (1983) Lancet ii, 355-357; Finne (1985) Trends Biochem. Sci. 10, 129-132; Rougon et al. (1986) J. Cell. Biol. 103, 2429-2437). We report that sera from patients suffering from group B meningitis exhibited IgM antibodies directed against the embryonic, but not the adult, form of neural cell adhesion molecules (N-CAM). These sera also stained live ATt20 cells as well as neuron membranes in mouse embryonic brain cultures. We have demonstrated that such antibodies, directed against carbohydrate moieties of bacterial capsula, were able to lyse cells expressing embryonic N-CAM in a complement-dependent cytotoxic assay. These data infer (1) that humans are able to develop anti-MenB humoral responses, (2) that such responses could initiate autoimmune disorders or be potentially detrimental by interfering with processes mediated by N-CAM interactions, (3) that the development of a vaccine against group B meningitidis should be considered with caution.

Lithostathine and pancreatitis-associated protein are involved in the very early stages of Alzheimer's disease

According to one of the theories formulated to explain the etiology of Alzheimer's disease (AD), amylosis may reflect a specific inflammatory response. Two inflammatory proteins, lithostathine and PAP, were evidenced by immunohistochemistry in senile plaques and neurofibrillary tangles of patients with AD. In addition, lithostathine and PAP were significantly increased in the cerebrospinal fluid of patients with AD when compared to patients with multiple sclerosis, another inflammatory disease, and to normal control subjects. However, no correlation was observed with age of occurrence. Furthermore, lithostathine and PAP were increased even at the very early stages of AD, and their level remained elevated during the course of the AD unlike TNFalpha whose level, very high at very early stages, regularly decreased. Finally, if part of lithostathine and PAP are synthesized in the brain, a large part comes from serum by passage over the blood-brain barrier. These results indicate (i) the existence of an acute phase response followed by a chronic inflammation in AD, and (ii) that lithostathine and PAP are involved even at the first pre-clinical biochemical events of AD. In addition, because lithostathine undergoes an autolytic cleavage leading to its precipitation and the formation of fibrils, we believe that it may be involved in amyloidosis and tangles by allowing heterogeneous precipitation of other proteins.

Chronic ataxic neuropathies associated with anti-GD1b IgM antibodies: response to IVIg therapy

OBJECTIVE

To determine the responses to treatment of patients with chronic sensory ataxic neuropathy associated with anti-GD1b IgM antibodies.

METHODS

Patients with chronic sensory ataxic neuropathy associated with anti-GD1b IgM antibodies followed in our department for at least 12 months between 2001 and 2008 were identified and studied retrospectively. Patients were tested at regular intervals using the INCAT disability score. Patients whose disability scores improved by at least one point were taken to have responded to the treatment. Intravenous immunoglobulin (IVIg; 2 g/kg) was administered for 3 to 5 days once every 6 weeks or corticosteroids at an initial daily dose of 1 mg/kg.

RESULTS

13 patients treated during the 8-year period of interest were included in this study. Seven of 13 patients displayed IgM anti-GQ1b, GT1b and GD3 antibodies suggesting reactivity against disialosyl epitope. IgM gammopathy was detected in four of six of serum with anti-disialosyl antibodies and two of the seven other sera. Nine of the 13 patients improved in response to IVIg. Oral corticosteroid treatment was attempted on four patients prior to IVIg treatment, and partial recovery occurred in one, who became steroid-dependent and showed little benefit in the long term.

CONCLUSIONS

Screening for anti-GD1b IgM antibodies should be carried out on all patients with chronic ataxic sensory neuropathies. In 69% of the cases studied, the patients' condition improved in response to IVIg. This study shows the short-term efficiency of this treatment. Sustained responses were obtained in the long term by continuing the infusions.

Serum levels of interleukin 1-beta, tumor necrosis factor-alpha, soluble interleukin 2 receptor and soluble CD8 in seronegative spondylarthropathies

Seronegative spondylarthropathies are disorders with the same predisposing antigen, namely HLA B27, a class I molecule of the HLA system. The mechanisms of the different diseases are unknown, and there is no proof of immune system participation. We have investigated patients with spondylarthropathies in order to search for an immunological component in the pathophysiology of these disorders, by measuring the serum level of two inflammatory cytokines--IL1 beta and TNF alpha--by a radioimmunological assay and the serum level of two soluble T cell activation markers--soluble IL2 receptor and soluble CD8--by an enzyme-linked immunosorbent assay. The choice of soluble CD8 can be explained by the strong link between HLA B27 and spondylarthropathies. Our series compared 24 patients to 24 healthy matched controls. A similar IL1 beta serum level was observed in both groups, while in the patients there was a nonsignificant increase in the TNF alpha level, a significant decrease in the soluble IL2 receptor level and a significant increase in the soluble CD8 serum level. The normal or moderately increased serum IL1 beta and TNF alpha levels in the disease group do not exclude a local role for these cytokines in the synovium or other inflammatory areas. However, we found a higher soluble CD8 serum level in the patient group. Most of these patients were in clinical exacerbation of their disease. As the serum level of soluble CD8 is well correlated with T CD8 lymphocyte activation, our data suggest that this lymphocyte subset is stimulated and consequently probably involved in seronegative spondylarthropathies.

Cryptogenic partial epilepsies with anti-GM1 antibodies: a new form of immune-mediated epilepsy?

PURPOSE

We wished to study immune system dysfunction which has been proposed as a potential cause of epilepsy. Epileptogenic action of antibodies directed against GM1 gangliosides was demonstrated in rats, but the potential role of anti-GM1 antibodies in human epilepsy has not yet been studied.

METHODS

We investigated the presence of IgG or IgM anti-GM1 antibodies in the sera of 64 patients with various types of epileptic syndromes: idiopathic generalized epilepsy (IGE) (n = 6), symptomatic or cryptogenic generalized epilepsy (SCGE) (n = 7), symptomatic partial epilepsy (SPE) (n = 26), and cryptogenic partial epilepsy (CPE) (n = 25).

RESULTS

Two patients had elevated titers of IgM anti-GM1 antibodies, one patient had elevated titers of both IgM and IgG anti-GM1 antibodies, and 1 patient had elevated titers of IgG anti-GM1 antibodies. All 4 patients had complex partial seizures (CPS) secondarily generalized, drug resistance, psychiatric disorders, and normal brain imaging. Anti-GM1 antibodies were never associated with IGE, SCGE, or SPE. We compared the reactivity of sera from these patients with the sera from 5 patients with motor neuropathies with conduction block (MNCB) against different gangliosides and concluded that epilepsy sera did not react with the Gal(beta 1-3)GalNAc epitope. Two anti-GM1-positive patients were treated successfully with high-dose intravenous immunoglobulins (IgIV).

CONCLUSIONS

Our findings suggest that detection of anti-GM1 antibodies could allow identification of a subgroup of patients with partial epilepsy associated with an autoimmune response. If anti-GM1 antibodies prove pathogenic, they could be an important prognostic factor for drug resistance and worsening of seizures.

Successful treatment with rituximab of one patient with CANOMAD neuropathy

We report a successful treatment with rituximab in a patient with CANOMAD neuropathy resistant to previous therapy. The titers of anti-disialosyl antibodies were decreased 3 months after the beginning of the treatment and the sensory ataxia clearly improved after 9 months of therapy.

Systemic amyloidosis AL with temporal artery involvement revealing lymphoplasmacytic malignancy in a man presenting as polymyalgia rheumatica

A 68 year old man presented with a clinical and biological picture that suggested polymyalgia rheumatica. Temporal artery biopsy disclosed no inflammatory change but massive light chain amyloid deposits in the media. Further exploration showed a malignant lymphoplasmacytic haemopathy with a triclonal gammopathy and a muscular, rectal, and probable cardiac amyloidosis. Cryoglobulinaemia and high concentrations of soluble interleukin 2 receptor (sIL-2R) were also found. This is the fifth case with confirmed involvement of the temporal artery. The especially high sIL-2R concentration was thought to reflect the tumour mass rather than lymphocyte activation.

Normalization of serum-free light chains in patients with systemic lupus erythematosus upon rituximab treatment and correlation with biological disease activity

Increased free light chain (FLC) levels have been reported as useful in various autoimmune conditions. We investigated how FLC concentrations change upon B cell targeted therapy in systemic lupus erythematosus (SLE) patients and if they correlate with disease activity. We retrospectively studied 11 SLE patients without renal failure, whom were treated with rituximab. Quantitative determination of IgG, IgA, IgM, and serum FLC was performed before and after rituximab. At baseline, 70% had abnormal serum FLC levels, including increased kappa and lambda levels, while the kappa/lambda ratio was normal for all. A strong correlation was observed between complement C3 fraction and kappa levels (r = -0.929, P < 0.001) or lambda levels (r = -0.854, P = 0.003), but not with IgG, IgA, or IgM levels. After rituximab treatment, kappa and lambda FLC concentrations decreased significantly whilst total concentrations of IgG, IgA, and IgM also decreased but remained within the normal range. There was a strong correlation only between kappa FLC levels and complement C3 fraction consumption (r = -0.543, P = 0.003). In SLE patients without renal failure, increased FLC levels (mainly kappa) with normal kappa/lambda ratios are a common feature, and in contrast to total IgG levels, FLC concentrations correlate with biological disease activity.

La réparation nerveuse périphérique : 30 siècles de recherche

INTRODUCTION

Nerve injury compromises sensory and motor functions. Techniques of peripheral nerve repair are based on our knowledge regarding regeneration. Microsurgical techniques introduced in the late 1950s and widely developed for the past 20 years have improved repairs. However, functional recovery following a peripheral mixed nerve injury is still incomplete.

STATE OF ART

Good motor and sensory function after nerve injury depends on the reinnervation of the motor end plates and sensory receptors. Nerve regeneration does not begin if the cell body has not survived the initial injury or if it is unable to initiate regeneration. The regenerated axons must reach and reinnervate the appropriate target end-organs in a timely fashion. Recovery of motor function requires a critical number of motor axons reinnervating the muscle fibers. Sensory recovery is possible if the delay in reinnervation is short. Many additional factors influence the success of nerve repair or reconstruction. The timing of the repair, the level of injury, the extent of the zone of injury, the technical skill of the surgeon, and the method of repair and reconstruction contribute to the functional outcome after nerve injury.

CONCLUSION

This review presents the recent advances in understanding of neural regeneration and their application to the management of primary repairs and nerve gaps.

Appearance of neurofilament subunit epitopes correlates with electrophysiological maturation in cortical embryonic neurons cocultured with mature astrocytes

E14 rat cortical neurons which have almost no glial progenitors were cocultured with a homogeneous population of mature type 1 astrocytes at a 4/1 ratio in serum free medium. Maturation of neurons was evaluated using a set of well characterized antibodies and two new monoclonal antibodies (MN2E4 and MN3H6) raised against various neurofilament subunits and whole-cell patch clamp experiments. We observed that this coculture method leads to a well-timed and very homogeneous neuronal maturation and that sequential appearance of neurofilament subunits in developing neurons correlates with the electrophysiological maturation. This sequence, early expression of the 68 kDa neurofilament subunit and late appearance of the 200 kDa neurofilament subunit, occurs in normal brain development, which validates this culture model as a useful tool for studying neuronal maturation and differentiation. MN2E4 staining (non-phosphorylated 200 kDa cytoskeletal protein antibody) appeared just before the neurons became excitable. It could thus be used as a functional neuronal marker. MN3H6 staining (phosphorylated 160-200 kDa neurofilament subunit antibody) appeared just after the neurons made synaptic contacts and generated synaptically driven spike bursts. This finding indicated that some phosphorylated epitopes of 160-200 kDa neurofilament followed synaptogenesis. These processes may play a key role in stabilizing the synapses to achieve a functional neuronal network.

Transfected trophoblast-derived human cells can express a single HLA class I allelic product

The human trophoblast-derived JAR cell line, that does not express polymorphic HLA class I antigens even after IFN induction, can be stably transfected by genomic clones encoding the entire HLA-A2, -A3 and -B7 alpha-chain genes. The transfected genes were expressed at the cell surface in association with endogenous beta 2-microglobulin (shown by FCM analysis) as a single allelic product without reexpression of any endogenous class I gene (shown by 1D.IEF analysis). Furthermore, TNF-alpha and IFN-gamma, alone and synergistically, increase cell surface expression of transfected MHC class I/endogenous beta 2m heterodimers without induction of endogenous class I alpha-chain genes. These data show that the MHC class I-negative JAR human cell line might be used for transfections with the aim of establishing human cells expressing just one defined MHC class I allele for functional and regulatory studies. These findings are discussed in relation to the methylated status solely of endogenous class I alpha-chain genes in JAR cells and suggest that transfected class I genes are not regulated in the same fashion and, in particular, that constitutive and TNF/IFN inducible trans-acting regulatory factors able to bind to cis-promoter/enhancer sequences of class I DNA are likely to be present.

Chronic plasminogen activator inhibitor-1 (PAI-1) overexpression dampens CD25+ lymphocyte recruitment after lipopolysaccharide endotoxemia in mouse lung

BACKGROUND

Plasma plasminogen activator inhibitor-1 (PAI-1) level rises during sepsis and confers a worse prognosis. PAI-1 participation to sepsis has been poorly documented and was mainly associated with fibrin deposits. Beside fibrin deposits, increased tissue PAI-1 expression may contribute to the poor outcome of endotoxemia through other mechanisms.

OBJECTIVE AND METHODS

During lipopolysaccharide (LPS) challenge, the role of PAI-1 in the early phase of inflammation was examined in the lungs of transgenic mice that either overexpress or lack the PAI-1 gene (PAI-1Tg or PAI-1(-/-)).

RESULTS

Analysis of leukocytes revealed that neutrophil and macrophage infiltrations did not differ for PAI-1Tg and wild-type (WT) mice. Remarkably, CD25+ lymphocyte infiltration was totally blunted in PAI-1Tg lungs and inversely correlated with fibrin depositions. In parallel, mRNA levels of the regulatory T cell (Treg) markers FoxP3, CTLA-4, and GITR were significantly lower in PAI-1Tg than in WT lungs after LPS challenge. These data are supported by opposite results in PAI-1(-/-) lungs. The systemic compartments (spleen and peripheral blood) showed no decrease in CD25+, CD4+ CD25+ lymphocytes, and Treg markers in PAI-1Tg mice after LPS injection compared with WT mice. In addition, plasma and lung concentrations of interleukin-6 (IL-6) and macrophage inflammatory protein-1alpha (MIP-1alpha) were significantly higher in PAI-1Tg mice than WT mice.

CONCLUSION

Our results suggest that chronic tissue PAI-1 overexpression influences the early phase of the inflammatory response during endotoxemia through the control of T lymphocyte traffic.

Neonatal lower motor neuron syndrome associated with maternal neuropathy with anti-GM1 IgG

The authors report a newborn with motor neuropathy associated with anti-GM1 antibodies from an affected mother. This finding suggests that the disorder was due to transplacental transfer of pathogenic antibodies.

Diagnostic insights into chronic-inflammatory demyelinating polyneuropathies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare immune-mediated neuropathy with demyelination of nerve fibers as leading morphological feature. The course of disease can be chronic progressive or remitting relapsing. Whereas for acute immune-mediated neuropathies several serological markers have been identified and used successfully in clinical routine, the serological diagnosis of chronic variants such as CIDP has not yet been evolved satisfactory. The typical CIDP and its various atypical variants are characterized by a certain diversity of clinical phenotype and response to treatment. Thus, diagnostic markers could aid in the differential diagnosis of CIDP variants and stratification of patients for a better treatment response. Most patients respond well to a causal therapy including steroids, intravenous immunoglobulins and plasmapheresis. Apart from electrophysiological and morphological markers, several autoantibodies have been reported as candidate markers for CIDP, including antibodies against glycolipids or paranodal/nodal molecules. The present review provides a summary of the progress in autoantibody testing in CIDP and its possible implication on the stratification of the CIDP variants and treatment response.

Le syndrome de l’homme raide : formes cliniques, traitement et profil évolutif

INTRODUCTION

Stiff-Man syndrome (SMS) is a rare neurological disease first described fifty years ago. There are several clinical forms, which are frequently misdiagnosed. The aim of this study is to review three of the main clinical forms.

MATERIAL AND METHODS

Case reports concerning three women suffering from different forms of SMS are presented, giving the main clinical features, their associations with other diseases, and the biological and electrophysiological findings.

RESULTS

The first patient presented a symmetric axial muscle rigidity, painful spasms and contractions of the trunk and limbs associated with anti-GAD antibodies. The common form of SMS was diagnosed and the patient was improved by intravenous immunoglobulin (IVIg). The second patient suffered from contractions and spasms localized to the lower limbs. In this patient, anti-GAD antibodies were absent. The Stiff-Leg syndrome was diagnosed and the patient was improved by intrathecal baclofen. The third patient presented rigidity of limb and trunk muscles associated with signs of encephalitis. In this patient, only anti-amphiphysin antibodies were present. The progressive encephalomyelitis with rigidity was diagnosed and the patient was improved by IVIg associated with corticosteroid.

CONCLUSION

Identifying patients with SMS makes it possible to propose appropriate medical management. There are several forms of the disease, and the severity of the evolution differs in each case. Treatment with GABA-ergic inhibitory drugs, IVIg and corticosteroid improve both the symptomatology and the quality of life of these patients.

Anti-beta 2-microglobulin monoclonal antibodies mediate a delay in HIV1 cytopathic effect on MT4 cells

We attempted to select monoclonal antibodies (mAb) which reacted with T-cell surface molecules and were able to interfere with the human immunodeficiency virus type 1 (HIV1) replicative cycle in the MT4 T-leukaemic cell line. In comparison with OKT4A, an anti-CD4 mAb, only one mAb, HC11.151.1, was found to significantly delay HIV-induced cytopathic effect on MT4 cells among the 15 mAb tested which reacted with MT4 cell surface antigens. Biochemical and immunological characterization of HC11.151.1 demonstrated its specificity for beta 2-microglobulin (beta 2m), the light chain of human leukocyte antigen (HLA) class I molecules. Other beta 2m-specific mAb were tested in order to assess whether this effect represented an intrinsic capacity of HC11.151.1 or whether it was a common feature shared by all anti-beta 2m mAb. Three (B1.1G6, B2.62.2 and BBM1) of the four anti-beta 2m mAb demonstrated the same protective effect, whereas C21.48A, which was devoid of a functional effect, was directed towards a beta 2m epitope involved in binding to the HLA class I heavy chain molecule. The physiological relevance of this observation is discussed.

Expression of cell surface and cytoskeleton developmentally regulated proteins in adult centronuclear myopathies

In order to evaluate the developmental status of myofibers in 3 cases of adult centronuclear myopathies (CNM) with type I predominance, we searched for the expression of (a) developmentally regulated cytoskeleton proteins (myosin heavy chains (MHC), vimentin, desmin), and (b) cell surface molecules (neural cell adhesion molecules isoforms, NCAM). Desmin intermediate filaments were overexpressed in some fibers with centrally located nuclei and radially organized. Muscle fibers do not express vimentin. These findings were not observed in muscle biopsies from disease controls with numerous central nuclei. Few myofibers (less than 5%) expressed developmental MHC together with either embryonic NCAM or adult NCAM and rare fibers only expressed adult NCAM. Most of the remaining fibers neither expressed NCAM nor developmental MHC but were slow MHC positive. These features do not favor the hypothesis of a general arrest of muscle fiber maturation in adult CNM. It is more likely that fibers undergo a very slow developmental process with a long delay of innervation as shown by some fibers with NCAM expression. Nevertheless, innervation appears to be successful, as suggested by the large number of NCAM negative fibers. Moreover, the abnormal myofiber distribution could be related to this functional disturbance of innervation.

A homologue of dystrophin is expressed at the blood vessel membrane of DMD and BMD patients: immunological evidence

Muscles from Becker muscular dystrophy (BMD) and Duchenne muscular dystrophy (DMD) patients were analysed using monoclonal and polyclonal antibodies raised against different regions of the dystrophin molecule. On blot, two of the antibodies detected a protein of Mr 400K in muscle extracts from all patients, including a BMD patient with a deletion which spanned more than 40% of the central rod domain of the Xp21 encoded dystrophin. Immunocytochemical labelling of tissue sections from the same patients showed that the same two antibodies labelled a protein at the surface membrane of smooth muscle fibers in blood vessels of both BMD and DMD muscles. Thus we have demonstrated a 400K blood vessel-associated protein, which is immunologically homologous with dystrophin, for at least two epitopes from the carboxy terminal and the central rod domains must be encoded by another gene than the dystrophin gene.