Eliminating false-positive results in serum tests for neuromuscular autoimmunity.

In this study we describe the false-positive frequency in radioimmunoprecipitation assays for muscle acetylcholine receptor (AChR) and neuronal voltage-gated potassium channel (VGKC) autoantibodies, attributable to 125I-ligand immunoprecipitation. Sera were evaluated for AChR autoantibody (n = 34,095) and VGKC autoantibody (n = 11,028). We retested sera that yielded apparently positive results with 125I-ligand with and without detergent-solubilized cation-channel protein, indentified clinically validated fals-positive rates of 0.05% and 1.7% for AchR and VGKC autoantibodies, respectively. Specificity assurance in radioimmunoprecipitation assays requires subtraction of values for 125I-ligand binding.

Use of intravenous immunoglobulin and plasma exchange in neurological disease.

PURPOSE OF REVIEW: The most relevant indications for the use of intravenous immunoglobulins and plasma exchange in neurological disorders are described, with special emphasis on the data from clinical trials and aspects of specific importance for clinical routine. RECENT FINDINGS: Much therapeutic success in neuromuscular and neuroimmunological diseases came with the therapeutic introduction of intravenous immunoglobulin and plasma exchange. Today, intravenous immunoglobulins and plasma exchange are preferentially used to treat acute Guillain-Barré syndrome, myasthenic crisis, acute or chronic inflammatory demyelinating polyneuropathy, or stiff person syndrome. Intravenous immunoglobulins also proved valuable for refractory dermatomyositis or multifocal motor neuropathy. Owing to their generally mild side effects, intravenous immunoglobulins have now been tested in many more indications, sometimes with surprising clinical effects as in the case of postpolio syndrome. While intravenous immunoglobulin is not the treatment of first choice in many immune-mediated disorders of the central nervous system, plasma exchange has become an integral part of escalating relapse therapy in relapsing-remitting multiple sclerosis. SUMMARY: In recent years, our knowledge on neurological disease mechanisms has broadened and more specific treatment alternatives have become available. Yet, established therapeutic options such as intravenous immunoglobulins and plasma exchange are still high on the list for many neuroimmunological disorders. Controlled trials have led to a refinement of the application of both treatment modalities, whose targets can be sometimes congruent, but in other cases also very distinct.

Evaluation of pteridine metabolism in battery workers chronically exposed to lead.

Occupationally-exposed lead affects the neuromuscular junction and might cause disturbances in the locomotor activity. This study was undertaken to evaluate pteridine metabolism, in which neurotransmitters are synthesized in battery workers. Urinary neopterin, biopterin and creatinine were measured using high performance liquid chromatography. Serum neopterin concentrations were detected by enzyme-linked immunoassay. Blood dihydropteridine reductase (DHPR) activities and deltaaminolevulinic acid (delta-ALA) were measured spectrophotometrically. Blood and urinary lead were detected by atomic absorption spectroscopy. Significantly increased blood and urinary lead levels, urinary neopterin, biopterin and delta-ALA were found in workers, while DHPR activities were indifferent compared to control group. Urinary creatinine decreased. This is the first study to demonstrate that increased activity of the pteridine pathway results in the accumulation of the neurotransmitters that may be responsible for the neurological disorders.