Isolation and characterization of rhesus monkey milk lactoferrin.

Rhesus monkey milk lactoferrin was isolated and its characteristics compared with those of human milk lactoferrin in order to assess the feasibility of using the rhesus monkey as an animal model for the study of iron absorption from milk. Monkey lactoferrin was isolated from pooled monkey milk by two chromatographic steps. Concentration of lactoferrin in milk, determined by rocket immunoelectrophoresis, demonstrated similar concentrations in both human and monkey milk, 1-2 mg/ml. Immunodiffusion of lactoferrins from several species using an antibody raised to money lactoferrin resulted in a cross-reaction only with monkey and human lactoferrin. Lactoferrins from cow, sheep, goat, dog, and rat milk were not recognized by the antibody. Amino acid analysis of monkey lactoferrin showed a composition very similar to human lactoferrin, as well as a similarity in the unusual amino acid sequence at the N-terminal of the protein. The carbohydrate moiety of monkey lactoferrin was investigated and shown to contain monosaccharides in similar proportions to those reported for human lactoferrin. In our opinion, the rhesus monkey is a promising model for the study of the role of lactoferrin in iron absorption in the infant, as well as of the other proposed actions of lactoferrin.