ABSTRACT
A correctly glycosylated myelin-associated glycoprotein (MAG) must express the carbohydrate epitope HNK-1, which is the target antigen for IgM antibodies in some patients with neuropathy. We transfected a human MAG cDNA clone into the neuroblastoma cell line SK-N-SH and verified by immunoblot the expression of the HNK-1 epitope on the recombinant molecule. By the same method and by indirect immunofluorescence we did not find any reactivity of human anti-MAG IgM antibodies with glycosylated recombinant MAG and transfected neuroblastoma cells. These findings suggest that the mere presence of the HNK-1 epitope is probably not sufficient for MAG to be recognized by human antibodies and that other factors such as the concentration or fine structure of this epitope in MAG, which mostly depend on the cellular context, may be also critical for this reactivity.
Subject(s)
CD57 Antigens/immunology , Gene Expression , Myelin-Associated Glycoprotein/biosynthesis , Myelin-Associated Glycoprotein/immunology , Neuroblastoma/metabolism , Antibodies/metabolism , CD57 Antigens/genetics , CD57 Antigens/metabolism , DNA, Complementary/genetics , Epitopes/immunology , Epitopes/metabolism , Fluorescent Antibody Technique, Indirect , Glycosylation , Humans , Immunoblotting , Myelin-Associated Glycoprotein/genetics , Neuroblastoma/genetics , Neuroblastoma/immunology , Neurons/cytology , Neurons/immunology , Phenotype , Recombinant Proteins/biosynthesis , Recombinant Proteins/genetics , Schwann Cells/cytology , Schwann Cells/immunology , Transfection , Tumor Cells, CulturedABSTRACT
Marked reduction in the contents of L-carnitine and acetyl-L-carnitine has been reported in peripheral nerves of rats with experimental diabetes. Since these substances have been claimed to improve a number of signs and symptoms of peripheral neuropathy in controlled clinical trials, this study was aimed at assessing whether nerves from diabetic subjects would also reveal similar decrease in the concentration of L-carnitine and acetyl-L-caritine. To this end, these substances were measured in nerves obtained from 11 patients with diabetic neuropathy, 13 patients with ischemic non-diabetic neuropathy, and 12 normal controls. Nerves from patients with either diabetic neuropathy and ischemic non-diabetic neuropathy showed levels of both carnitines lower than those from normal controls. However, differences among the three groups were not statistically significant, indicating that a reduction in these amino acids probably represents only a co-factor in the development of the variegated clinical picture of human diabetic neuropathy.
