Abstract: Provided herein are methods of treatment designed to prevent or minimize formation of deleterious multivalent immune complexes in a human patient having a complement mediated disorder (e.g., paroxysmal nocturnal hemoglobinuria (PNH) or atypical hemolytic uremic syndrome (aHUS)), who has been or is being treated with a first anti-C5 antibody and is then treated with a second (different) anti-C5 antibody, as well as methods of safely switching a patient from treatment with a first anti-C5 antibody to a second (different) anti-C5 antibody. Also provided are methods for determining an adjusted regimen antibody (e.g., a regimen to prevent or minimize formation of multivalent immune complexes) comprising an adjusted therapeutic dose and/or timing of administration of a second anti-C5 to treat a patient who has been or is being treated with a first anti-C5 antibody.

Abstract: A method for measuring the protease activity of a convertase of the alternative complement pathway is provided. The method typically comprises immobilizing a biotinylated C3b on a solid phase coated with a biotin binding protein. Substantially homogeneous components of the alternative complement pathway may be incubated with the immobilized C3b in a serum free and a gelatin free buffer, to form a convertase. The activity of the convertase is generally measured with an immunoassay.

Abstract: A method for measuring the protease activity of a convertase of the alternative complement pathway is provided. The method typically comprises immobilizing a biotinylated C3b on a solid phase coated with a biotin binding protein. Substantially homogeneous components of the alternative complement pathway may be incubated with the immobilized C3b in a serum free and gelatin free buffer, to form a convertase. The activity of the convertase is generally measured with an immunoassay.

Abstract: A method for measuring the protease activity of Factor D for its natural substrate is provided. Factor D activity may be measured with an immunoassay or a biosensor. The method typically comprises immobilizing a biotinylated C3b on a solid phase coated with a biotin binding protein. Substantially homogeneous components of the alternative complement pathway may be incubated with the immobilized C3b to form a convertase. An immunoassay or a biosensor is generally used to measure the formation of Bb.