Allergenicity Assessment of a Genetically Modified Protein-Recombinant Human Lactoferrin

Introduction Human lactoferrin (hLF) is known to be a multifunctional protein of the transferrin family. It is a glycoprotein of approximately 80KDa and is present in various human secretory fluids including milk, saliva, tears and nasal secretions as well as being abundant in neutrophils [1-4]. The hLf protein includes 703 amino acids as a single polypeptide chain that folds into two similar globular lobes—C-and N-terminal regions. The structure is maintained by multiple intra-chain disulfide bonds and the lobes are connected by a short α-helical region. The isoelectric point of hLf is 8.7 and there are two iron binding sites and 5 potential asparagine-linked glycosylation sites in the molecule [5]. The degree of glycosylation of the protein varies with the tissue of expression and the metabolic status of the producing cells [6]. Each lactoferrin molecule can reversibly bind two ions of iron with high affinity, but it may also bind zinc, copper or other metals with lower affinity [7]. After combining with iron, it forms a reddish complex. The affinity for iron is 300 times higher than that of transferrin, although the amino acid sequences are 60% identical [8]. The characteristics of hLF were first published in 1984 and the similarities to transferrin were noted [5]. The concentration of lactoferrin in human milk is approximately 7 g/L, much higher than in milk of non-primate species of mammals. Human lactoferrin has been demonstrated to have antibacterial, antiviral, anti-inflammatory and antioxidant properties [9-16]. It can interact with human cells to modulate the inflammatory process and innate defense reactions [17]. Lastly, dietary hLF provides an important mechanism for efficient iron absorption, especially in the neonate, as well as promoting intestinal epithelial cell growth [17]. Researchers have considered using hLF in a wide variety of applications due to its bioactivities. Potential applications include the prophylactic treatment of inflammatory disease [18,19] and iron Abstract Background: Recombinant human lactoferrin (rhLF) has previously suggested serving as food additive due to the natural iron binding properties that provide anti-microbial activity. Recombinant cows have been produced that express hLf in milk. However, the potential allergenicity of hLf has not been previously assessed. This research is conducted to evaluate the potential allergenicity of rhLF as a prerequisite for food use.