CONCENTRATION FUNCTION RELATIONSHIPS IN THE ALTERNATIVE PATHWAY OF HUMAN-COMPLEMENT ACTIVATION

The dependence of the rate of human complement-mediated lysis of rabbit erythrocytes on concentrations of factors B and D of the alternative pathway is characterized by saturation kinetics. At low B and D concentrations no lysis occurs until a certain ''threshold'' concentration of the respective factor has been reached The dependence of the lysis rate on C3 concentration is wavelike, i.e., at some C3 concentrations erythrocyte lysis is inhibited. It is supposed that C3 not only mediates the complement-dependent hemolysis but also plays a prominent role in self-regulation of this process.