OBJECTIVE: To review the main characteristics of the 'immune complex (IC) transport system of erythrocytes', and its possible relevance for transfusion medicine. DATA SOURCES: Literature search, and results Of Studies performed in the laboratory of Dr J. Schifferli from 1986 to 1995. SELECTION CRITERIA: Peer review journals and work relevant to the topic. RESULTS: When antigen/antibody IC form in the presence of complement. C3b binds covalently to the complexes. Such opsonized complexes attach to cells bearing complement receptor 1 (CR1), which is mostly found on erythrocytes in the circulation. This allows IC to be transported through the circulation to the fixed macrophage system of the liver and spleen. In addition, C3b bound to the complexes is catabolized by factor 1 (with CR1 as a cofactor) so that the complement-activating properties of the complexes are reduced. CONCLUSIONS: Complement and erythrocyte CR1 contribute to the safe and effective elimination of IC in humans. This physiologic system prevents IC deposition in the vessel walls.