COMPLEMENT COMPONENT-1 INHIBITOR (C1-INH) LIKE PROTEIN ON MURINE SPERMATOZOA - ANTI-C1-INH INHIBITS IN-VITRO FERTILIZATION

We investigated if complement component 1 inhibitor-like (C1-INH-L) pr otein found on human spermatozoa exists on mouse spermatozoa and is re levant to reproduction. We used Western blot analysis and immunofluore scence assays to detect C1-INH on murine sperm and tested the effects of the antibodies to C1-INH and albumin (negative control) on in vitro mouse sperm motility and fertilization. C1-INH-L, with molecular weig ht similar to human C1-INH (100 kDa), was present on the surface of sp ermatozoan head and midpiece, Treating mouse sperm with anti-C1-INH re duced the mouse sperm motility (P<0.01), in vitro fertilization (P<0.0 1) and embryo development rates (P<0.01). Anti-albumin failed to do so . We conclude that C1-Inhibitor-like protein is present on mouse sperm surface and appears to be relevant to reproduction.