ABSTRACT
A panel of mouse monoclonal antibodies to rat and human myelin-associated glycoprotein (MAG) was developed. Normal mice were unresponsive to rat MAG, and successful immunization with rat MAG was only achieved in autoimmune NZB mice. By contrast, all strains of mice were responsive to human MAG. The monoclonal antibodies developed differ with respect to immunoglobulin type, their specificity for human and/or rat MAG, and their recognition of protein or carbohydrate epitopes in MAG. In general, the antibodies that react with the protein backbone recognize both rat and human MAG, whereas a large number of the monoclonal antibodies recognize a carbohydrate determinant in human MAG that is not in rat MAG. Immunocytochemical staining of adult human spinal cord with the monoclonal antibodies resulted in periaxonal staining of myelin sheaths similar to that produced by well-defined, rabbit, polyclonal anti-MAG serum. In addition, the antibodies recognizing carbohydrate determinants in human MAG strongly stained oligodendrocyte cytoplasm. These monoclonal antibodies will be of value for the further chemical and biological characterization of MAG.
Subject(s)
Antibodies, Monoclonal/biosynthesis , Myelin Proteins/immunology , Animals , Epitopes/analysis , Epitopes/immunology , Humans , Mice , Mice, Inbred BALB C/immunology , Mice, Inbred C3H/immunology , Mice, Inbred C57BL/immunology , Mice, Inbred NZB , Myelin-Associated Glycoprotein , Rats , Species SpecificityABSTRACT
The IgM in three patients with paraproteinemia and peripheral neuropathy was shown to bind to human myelin-associated glycoprotein (MAG) that had been purified to homogeneity by gel filtration on Sepharose CL-6B. The antigenic determinant reacting with the IgM from all three patients was in the carbohydrate part of the MAG molecule. In addition, the IgM from the same three patients bound to a single ganglioside of human sciatic nerve. The results indicate that the IgM paraproteins in these patients react with a carbohydrate determinant that is shared between MAG and a peripheral nerve ganglioside.
Subject(s)
Epitopes/analysis , Gangliosides/metabolism , Immunoglobulin M/metabolism , Myelin Proteins/metabolism , Paraproteinemias/physiopathology , Peripheral Nervous System Diseases/physiopathology , Brain , Enzyme-Linked Immunosorbent Assay , Gangliosides/isolation & purification , Humans , Immunoglobulin M/isolation & purification , Myelin Proteins/isolation & purification , Myelin-Associated Glycoprotein , Paraproteinemias/complications , Paraproteinemias/immunology , Peripheral Nervous System Diseases/complications , Peripheral Nervous System Diseases/immunology , Protein Binding , Sciatic NerveABSTRACT
P2 protein, a myelin-specific protein, was detected immunocytochemically and biochemically in rabbit central nervous system (CNS) myelin. P2 protein was synthesized by rabbit oligodendrocytes and was present in varying amounts throughout the rabbit CNS. Comparison of P2 and myelin basic protein (MBP) stained sections revealed that P2 antiserum did not stain all myelin sheaths within the rabbit CNS. The proportion of myelin sheaths stained by P2 antiserum and the amount of P2 detected biochemically were greater in more caudal regions of the rabbit CNS. The highest concentration of P2 protein was found in rabbit spinal cord myelin, where P2 antiserum stained the majority of myelin sheaths. P2 protein was barely detectable biochemically in myelin isolated from frontal cortex, and in sections of frontal cortex only occasional myelin sheaths reacted with P2 antiserum. These results suggest the the regional variations in the amount of P2 protein are dut to regional differences in the number of myelin sheaths that contain P2 protein. P2 protein was detected immunocytochemically and biochemically in rabbit sciatic nerve myelin. Immunocytochemically, P2 antiserum only stained a portion of the myelin sheaths present. The myelin sheaths not reacting with P2 antiserum had small diameters and represented less than 10% of the total myelinated fibers.
