myelin-basic-protein and Hemolysis

Cultured rat oligodendrocytes are lysed by complement via antibody-independent activation of the classical pathway. This susceptibility to complement lysis has been demonstrated to be due to lack of CD59, a complement regulatory protein which inhibits assembly of the membrane attack complex. In this study the effects of homologous and heterologous complement were examined in a co-culture system of rat oligodendrocytes and peripheral neurones, where axonal ensheathment was observed as early as 4 days after the addition of glial progenitors to the neurones. Following exposure to complement, ensheathing oligodendrocytes were markedly less sensitive to antibody-independent but not antibody-dependent complement lysis than were cells grown without neurones. Immunocytochemical data revealed that co-cultured oligodendrocytes remained CD59 negative, but in contrast to oligodendrocytes cultured alone, were negative for C3b when incubated with C7-deficient serum. Taken together these data indicate that the decreased sensitivity of co-cultured oligodendrocytes to complement lysis is not attributed to the increased expression of CD59, but rather in a failure to activate complement. Incubation of oligodendrocytes with neurone-conditioned medium afforded significant protection (68%), against antibody-independent complement attack, suggesting that soluble neuronal factors can protect oligodendrocytes from complement-mediated lysis.

Topics: Animals; Animals, Newborn; CD59 Antigens; Cell Survival; Cells, Cultured; Coculture Techniques; Complement System Proteins; Culture Media, Conditioned; Ganglia, Spinal; Hemolysis; Microscopy, Confocal; Myelin Basic Protein; Neurons; Oligodendroglia; Rats; Rats, Sprague-Dawley; Spinal Cord

The participation of terminal complement complexes (TCC) in demyelination has been shown in rodent cerebellar cultures. Since TCC modulates activities of various membrane-associated enzymes and increases the level of cellular Ca2+ we investigated whether TCC could activate Ca2+-dependent neutral proteases in myelin that would lead to hydrolysis of myelin basic protein (BP). Addition of antibody and C7-deficient serum plus C7 to sealed myelin vesicles of two to six bilayers caused significant BP hydrolysis compared to the hydrolysis caused by antibody and C7-deficient serum. Significant hydrolysis occurred at the stage of C5b6,7 assembly, which increased in magnitude at the C5b6-8 stage. C5b6-9 formation did not enhance the effect of C5b6-8. BP hydrolysis by C5b6,7 did not require Ca2+ whereas the effect of C5b6-8/C5b6-9 was, in part, Ca2+-dependent. We postulated that TCC formation in myelin membranes causes activation of myelin-associated neutral proteases with subsequent hydrolysis of BP as a consequence of complement peptide insertion and channel formation. Such processes may alter the structure of myelin and augment the action of other inflammatory cells and their products in demyelinating diseases that could ultimately lead to the loss of myelin.

Topics: Complement Membrane Attack Complex; Complement System Proteins; Hemolysis; Humans; Hydrolysis; Kinetics; Myelin Basic Protein; Myelin Sheath; Spinal Cord; Trypsin

Topics: Animals; Antibody Formation; Antigens; Ascitic Fluid; Autoantibodies; Brain; Cell Migration Inhibition; Cells, Cultured; Chromatography, Gel; DNA; Guinea Pigs; Hemolysis; Iodine Radioisotopes; Lymphocyte Activation; Lymphocytes; Macrophages; Myelin Basic Protein; Peptides; Radioimmunoassay; Spleen; Thymidine; Tritium

Topics: Animals; Binding Sites, Antibody; Cells, Cultured; Complement System Proteins; Erythrocytes; Hemagglutination Tests; Hemolysis; Hydrogen-Ion Concentration; Immunization; Immunoglobulin G; Lymph Nodes; Lymphocyte Culture Test, Mixed; Lymphocytes; Lymphotoxin-alpha; Macrophage Migration-Inhibitory Factors; Mice; Mice, Inbred C3H; Mice, Inbred DBA; Mitogens; Mitomycins; Molecular Weight; Myelin Basic Protein; Rats; Rats, Inbred Lew; Sheep