Isolation and partial characterization of ovine lactoferrin

Infusion of ovine C5a into sheep mimics the inflammatory response of hemodialysis

Previous studies in our group have explored the inflammatory response in sheep to dialysis with a variety of different hemodialysis membranes. In the present study we investigated the potential role of C5a in mediating inflammatory responses that have been attributed to complement activation in the extracorporeal setting. Sheep C5a was infused into sheep in a manner that simulated exposure to this anaphylatoxin during dialysis. C5a infusion into sheep was shown to produce a dose-dependent neutropenia that was quantitatively and temporally identical to the response of sheep undergoing dialysis with complement-activating membranes. The two lowest doses used (0.25 and 0.50 micrograms/kg), which resulted in concentrations below the detectable limits of current assays (10 ng/ml), produced significant neutropenia (21.8% and 78.1%, respectively). The ability of the neutrophils (PMNs) to bind fluorescein isothiocyanate-C5a or initiate a respiratory burst in response to phorbol myristate acetate were also affected in a dose-dependent manner. In contrast, C5a alone was not able to produce significant release of lactoferrin, a specific granule constituent, suggesting that degranulation of PMN-specific and primary granules requires secondary stimuli. The production of thromboxane A2 and thromboxane's consequent cardiopulmonary effect of increasing mean pulmonary artery pressure were both observed in a dose-dependent fashion. However, larger amounts of C5a were required to elicit these latter responses as compared with the PMN activities. These results suggest that C5a may be a primary mediator of complement-dependent events that occur during extracorporeal therapies such as hemodialysis, and they also suggest that very little complement activation is necessary to activate leukocytes, whereas higher thresholds are required to produce cardiopulmonary responses.

Ovine lactoferrin: isolation from colostrum and characterization

Highly purified lactoferrin was isolated from ovine colostrum by sequential purification on CM-Sephadex C-50 and Blue-Sepharose, with overall yield of 55%. The ovine lactoferrin was characterized by SDS-PAGE, its amino acid composition and N-terminal sequence to residue 30. Homology with bovine and human lactoferrins was greater than 80 and 50% respectively. Antibodies to ovine lactoferrin were raised in rabbits and used to develop an enzyme-linked immunosorbent assay (ELISA). The antiserum was not cross reactive with other colostrum proteins.

Comparison of bovine, sheep and goat milk lactoferrins in their electrophoretic behavior, conformation, immunochemical properties and lectin reactivity

1. The biochemical properties of bovine, goat and sheep lactoferrin were compared. Molecular weights of the three lactoferrins were estimated to be 78,000 to 80,000 as determined by SDS-PAGE. By IEF, microheterogeneity was observed for all of them. 2. Partial antigenic identity was observed between bovine lactoferrin and goat or sheep lactoferrin by immunodiffusion method. 3. CD spectra at the u.v. region of the three lactoferrins suggested their similar secondary and tertiary structural profiles. 4. Reactivities with peroxidase-conjugated lectins showed that the carbohydrate compositions of the three ruminants' lactoferrin were the same but not identical with that of human lactoferrin.