STEADY-STATE APPROXIMATION IN THE MINIMAL MODEL OF THE ALTERNATIVE PATHWAY OF COMPLEMENT

Complement is a response mechanism of the immune system. Two initiatio n pathways have been characterized for complement. The classical pathw ay is antibody mediated while the alternative pathway is not. Since th e alternative pathway is independent of antibodies, it is always activ e. For the alternative pathway we have previously developed a minimal model. Using parameters within physiological bounds, the model showed complex behavior also within physiological bounds. Thus the model seem s to be an appropriate representation of the alternative pathway respo nse. By applying a steady state assumption to the Michaelis Menten ste p of the minimal model, we reduce the number of variables from six to five. A comparison between the dynamics of the minimal and contracted models reveals that the two descriptions may not be compatible. Althou gh both systems show chaotic behavior it occurs in different regions o f parameter space. (C) 1997 Elsevier Science B.V.