Biological effects of complement

Tlie two principal biological effects of complement component C5a are... 

Reaction Sequence - There are several pathways by which all or part of the complement system cem be activated. The nexus of these various activation pathways, the C3 molecule, and the later-acting complement components, yield the bulk of the biologically active con nents of the complement system. However, as will be described shortly, some of the biological effects of complement are the consequence of the action of Cl, C4, and C2 alone. 

Biological Effects of Complement - Activation of the complement system under appropriate conditions leads to the generation of a number of biologically active fragments that participate in the inflamnatory response. Activation of all nine of the components results in membrane damage (i.e., cytolysis, bacteriolysis, and possibly the immunopathogenic lesions of im-mtuie complex disease). 

The chapters in this book were carefully selected to complement the existing information on plant proteins by focusing on the A, B, C s applications in new and traditional foods, biological effects of all-vegetable protein diets on humans, and composition and chemistry of some lesser-known sources of protein... 

Kolb, W.P., Savary, J.R., Troup, C.M., Dodd, D.E., Tamerius, J.D. (1987). Biological effects of short-term, high concentration exposure to methyl isocyanate. VI. In vitro and in vivo complement activation studies. Environ. Health Perspect. 72 189-95. 

Sera from levamisole-treated mice, rabbits and man were found to yield a dialyzable, complement-unrelated serum factor which did not contain any levamisole metabolites, but which could simulate the biologic effects of levamisole itself. 162 This factor enhanced carbon clearance,169 stimulated lymphocyte proliferation in vitro,187 restored immunological reactivity of athymic mice,179 induced in vitro maturation of mouse pre-T cells,179 stabilized tumor remission and reduced tumor load in experimental systems.162 The factor could not be detected in mice which failed to respond to treatment with levamisole but non-responders reacted to serum factor in a similar way as responders treated with levamisole itself.162 a perhaps identical serum factor could also be induced by the sulfhydryl compound diethyl-dithiocarbamate (65).1 which appears to share some of the immunoenhancing and immunorestorative properties of levcimisole if administered in... 

As a result, the serum complement system is now known to consist of nine distinct proteins that interact to mediate and amplify many of the biological effects of immune reactions (1,2). 

C5a is a fragment of the parent molecule with a molecular weight of about 10(000. The actions of both anaphylatoxins can be blocked by antihistamines, but apparently the biological effects of each operate via separate mechanisms since smooth muscle no longer sensitive to C3a can be stimulated by C5a. It should be noted that response of smooth muscle to anaphylatoxin exhibits tachyphylaxis whereas the response to histamine does not. It is clear, however, that activation of the complement system at least through C3 leads to complement-dependent histamine release. This phenomenon is mediated by immunoglobulins other than IgE. 

The physical phenomena causing retention in HIC are basically the same as in solvophobic RPC. In HIC, the moderate binding power of the packing is complemented by the salting-out effect of the mobile phase. The mild conditions of HIC provide the best chance for recovering proteins of biological activity. 

Natural and synthetic compounds with biological activity exert their biological effects only in solution. Simple relationships between the solid-state structures of such compounds and their biological activities can not be expected, since dissolution of the substances in water may change their structure and composition dramatically. For kinetically labile metal complexes, the presence of several species in equilibrium with one another in the same solution makes the picture even more complicated. This is why the equilibrium study of complex formation in biologically active systems has to be complemented by structural investigations. 

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