Complement, the immune-complex lattice, and the pathophysiology of complement-deficiency syndromes.

The role of the components of the complement classical pathway in maintaining antigen-antibody complexes in solution has implications for the understanding of the pathophysiology of complement-deficiency syndromes. It is proposed that this mechanism may normally keep immune complexes soluble for a sufficient time for their safe elimination by the mononuclear phagocyte system. When an early component of the classical pathway is deficient or depleted antigen-antibody complexes would be more likely to precipitate at or near their site of formation and lead to immunologically mediated inflammation. This hypothesis is supported by the predisposition to immune-complex diseases of patients with genetically determined deficiencies of components of the classical pathway.