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>Now while you two are still talking to the list, what is the compliment
>system (apparently has nothing to do with being nice to each other :>)
>and where  can I get a better one?

The complement system consists of at least 9 plasma proteins (designated
C1-C9).  When activated, the systems augments and encourages many immune
responses.  The major biological effects of complement results from the
breakdown (or conversion) or components C3, and C3 can be converted (into
C3a and C3b) by activation of either of two pathways.  The classical pathway
for complement activation usually involves antigen-antibody complexes, 
although the pathway can be "triggered" by immunoglobulin aggregates, and
components C1, C4 and C2 are involved (and consumed).  The conversion of 
C3 can also be activated via an "alternative" or properdin pathway - 
independent of components C1, C4 and C2, an dnot requiring antigen-antibody
complex formation.  Endotoxin, bacterial wall polysaccharides and immuno-
globulin aggregates are capable of activating complement via the alternative
pathway, as are several drugs and apparently via micro-bubbles produced via
diving/dcs.  Amplification of C3 conversion via this route results from a 
positive feedback loop involving the major C3 clevage product C3b.  Following
conversion of C3 (by either pathway), and 'attack sequence' results from
the sequential involvement of further complement components in an amplifying
'cascade', with the ultimate formation of a complex molecule (C5-9) capable
of cell membrane damage.  The rate of complement activation is regulated by
several mechanisms.  The positive feedback loop already mentioned is
balanced by regulation resulting both in from the inherent rapid decay of
several components and the involvement of inhibitor and inactivator molecules.

The biologic results of complement activation  include the release of 
anaphylatoxins (causing vasodilation and increased capillary permeability),
enhancement of immune adherence (important for phagocytosis), the release
of histamine and chemotactic factors and cell lysis.  Furthermore, the 
complement system plays a part in the induction of specific immune responses.
Although complement augments many host protective mechanisms, activation
may result in damage to host tissus. 

There is work that implicates complement in many of the presentations seen
in severe DCS that are not easily explained just by blocked blood flow to
tissues (severe shock, widespread edema, etc.).

Hope this helps -

John 
Submariner Research, Ltd.
(johncrea@de*.co*) 

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