We have previously discussed the importance of T cells in the
initiation and maintenance of multiple sclerosis. For example,
it is known that CD4 T cells infiltrate the central nervous
system of patients with multiple sclerosis and that through
secretion of cytokines they induce microglial activation
(associated with glutamate toxicity), as well as directly
contribute to demyelination. An interesting component of the
immune system that is only recently beginning to attract
significant attention is the complement cascade. This series of
proteins is activated either by antibodies, or by proteins that
secrete a “danger” signal to the body. The activation of the
complement cascade results in the formation of an “arrow-like”
protein structure that inserts itself into the cellular membrane
and results in the killing of the target cell. This protein
structure is called the “membrane attack complex”. Usually
immunologists think of complement as a means of the immune
system clearing bacteria and other pathogens, howev