USING ELISA TO EVALUATE COMPLEMENT ACTIVATION BY REFERENCE BIOMATERIALS

The interaction between blood and an artificial surface results in the activation of complement and can lead to extensive inflammatory reactions. In vitro work was undertaken to validate a system of assays to evaluate the complement activation of a candidate biomaterial by comparing its capacity of activation with that of reference biomaterials. The biomaterials tested were cellulose acetate, cellulose dialysis tubing, low density polyethylene, polydimethylsiloxane and AN69. Complement activation was assessed using ELISA for iC3b, C3a and Factor Bb. Results showed that (1) iC3b measurements may underestimate complement activation, (2) the presence of Bb in plasma or serum was a reliable indicator of complement activation, (3) measurements of C3a are of interest but are difficult, (4) adsorption or/and binding of complement proteins occured on the surface. Evaluation of complement activation for a biomaterial should include the assessment of the fluid phase (in serum or plasma) as well as the bound phase (on the surface of the biomaterial) of complement.