Three membrane-bound complement regulatory proteins, namely
membrane cofactor protein (MCP), decay acceleration factor (DAF), and
membrane attack complex inhibiting protein (CD59), are differentially
expressed in the human eye. Sohn et al. (p. 4195) report that normal
human aqueous humor and vitreous contain soluble forms of MCP, DAF, and
CD59, which are functionally active. Thus, identification of
membrane-bound and soluble complement regulatory proteins in normal
human eye provides evidence that a regulatory system exists to protect
these cells from destruction by complement activating events during an
inflammatory response. Additionally, soluble complement regulators may
be therapeutically useful in suppression of intraocular inflammation
and tissue damage.