PROBLEM: We evaluated the hypothesis that different tissue substructures in uteri may express decay accelerating factor (DAF), a complement regulatory protein that also may serve as ligand for bacterial attachment.
METHOD: Purified Dr pili, anti-Dr pili IgG, anti-DAF (SCR-3) IgG, and fluoresceinisothiocyanate-conjugated secondary IgG were used for binding and inhibition experiments. RESULT: We observed staining of endometrial glands, spiral arterioles, and myometrial arteries with Dr adhesin (pili) and anti-DAF (SCR-3) IgG, and found variation in distribution and amount of Dr ligands in different individuals. Anti-DAF (SCR-3) IgG blocked the binding of Dr pili to the endometrium.
CONCLUSION: Presence of DAF in endometrium may protect tissues from complement-induced damage. Differences between individuals in DAF density in the endometrium may affect sensitivity to attachment of Dr-bearing E. coli and/or complement activation.