No Detectable Transfer of Dietary Lactoferrin or Its Functional Fragments to Portal Blood in Healthy Adult Rats

Abstract

We investigated the transfer of dietary bovine lactoferrin (LF) and its functional lactoferricin (LFcin) B-containing fragments to the portal blood of healthy adult rats by using several techniques. After a single administration of ¹²⁵I-labeled LF, radioactive bands were detected in autoradioluminograms of the portal blood, but similar bands were also observed after the administration of [¹²⁵I]NaI. Although ovalbumin was detected by ELISA at 3–18 ng/ml in the portal blood plasma after an overnight administration, no LF was detected (≤1.5 ng/ml). The antibody-captured ovalbumin fragments, but not the LF fragments, were detected in the plasma by surface-enhanced laser desorption/ionization affinity mass spectrometry (SELDI affinity MS). We finally attempted to detect the LFcin B-containing fragments by SELDI affinity MS with on-chip LFcin B-conversion, but could not detect them (≤1 ng/ml) in the portal blood after the LF ingestion. The level of LF or its functional fragments transferred to the portal blood was therefore extremely low, if any.