Isolation of membrane attack complex of complement from myelin membranes treated with serum complement

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• The complement system plays a role in myelin damage and clearance.
• Complement activation generates opsonins and the membrane attack complex (MAC).
• Previous studies showed myelin activates complement and MAC is crucial for antibody-mediated demyelination.

Purpose of the Study:

• To investigate if myelin-mediated complement activation leads to MAC formation on myelin membranes.
• To understand the role of MAC in complement-mediated demyelination.

Main Methods:

• Incubation of isolated myelin with fresh serum.
• Ultracentrifugation of myelin-associated proteins on a sucrose density gradient to detect C5b-9 neoantigen.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotting, and immunostaining to determine C5b-9 subunit structure.

Main Results:

• Myelin membranes were shown to assemble the macromolecular complex of late-acting complement components (C5-C9).
• This assembly indicates the formation of the membrane attack complex (MAC) directly on myelin.
• The findings confirm the presence of C5b-9 neoantigen in myelin-associated protein extracts.

Conclusions:

• Complement activation by myelin membranes results in the assembly of the membrane attack complex (MAC) on the myelin.
• This confirms a direct mechanism for complement-mediated myelin damage and disposal.
• The study elucidates the role of MAC in the interaction between complement and myelin.