[Comparison of the complement-binding activity of model immune complexes of different molecular weights].

The authors studied and compared the complement-fixing activity of model immune complexes with different molecular mass. The complement-fixing activity of the complexes was found to be linearly independent of the molecular mass, being mainly determined by the size of the complex, and to be slightly dependent on the concentration of aggregated immunoglobulins. As far as the aggregates with a molecular mass over 20 IgG are concerned, addition of complement leads to the dissociation of the complexes.