CR1 and CR1-like: the primate immune adherence receptors

Immune adherence describes the phenomenon in which complement-opsonized substrates, such as immune complexes (IC), viruses, or bacteria, are bound by primate erythrocytes via erythrocyte complement receptors. In vivo studies have shown that this binding allows the erythrocyte to act as an inert shuttle, targeting IC to the monocyte phagocytic system and away from vulnerable tissue. Thus, immune adherence appears to play an integral role in the primate in promoting the safe clearance of circulating IC and preventing IC-mediated pathologies. The complement receptors that mediate immune adherence comprise two unique but closely related gene products, either the type one complement receptor (CRI) in humans or CR1-like in non-human primates. This review focuses on the structure, function, and physiological role of the primate immune adherence receptors.