Artym Jolanta
Zakład Terapii Doświadczalnej Instytutu Immunologii i Terapii Doświadczalnej PAN im. L. Hirszfelda we Wrocławiu, 53-114 Wrocław.
Postepy Hig Med Dosw (Online). 2010 Nov 30;64:604-16.
Lactoferrin (LF) is a glycoprotein widely distributed in mammalian organisms. It is synthesized by epithelial cells; hence it is present in secretions of mucous membranes. It is also contained in secondary granules of neutrophils and released to the circulation during trauma, infection or inflammation. LF belongs to the transferrin family--proteins binding iron ions with a high affinity. Upon isolation in 1961 LF was initially called a red, iron-binding protein. LF's ability to bind iron is associated with other functions which the protein fulfils in the body. As described in the part I. of the article, LF participates in acquisition of iron from food and its storage in the body, and to a certain degree also in iron transport to cells. In this part of the article the effect of LF in combating microorganisms by chelating iron is described. The iron-chelating property of LF renders iron inaccessible to the pathogens, thus restricting their growth. Iron, due to its participation in many metabolic processes, is an essential element for almost all microorganisms. Iron is not easily accessible for pathogens within the host. Since iron is crucial for normal function of both pathogens and the host, an ability to acquire iron during infection is regarded as an important virulence factor. Higher vertebrates have evolved a complicated protection system of iron storage and LF is an important element of this system. Low iron-saturated LF effectively combats bacteria and fungi, acting in a bacteriostatic and fungistatic way. The degree of iron saturation also influences antiviral activity of LF. Some pathogens (e.g. Helicobacter pylori, Neisseria sp, Haemophilus influenzae) have evolved a system of siderophores or cellular receptors which can acquire iron from LF and transferrin. The so-called lactoferrin theory of hypoferremia in inflammation assumes, in addition, a protective role of the protein in inflammation, sepsis and trauma. LF, by chelation and storage of plasma iron in the liver and spleen, temporarily restricts its accessibility for microorganisms and processes of formation of toxic, reactive oxygen species, which contributes to the amelioration of inflammatory states.
乳铁蛋白（LF）是一种广泛分布于哺乳动物机体中的糖蛋白。它由上皮细胞合成，因此存在于黏膜分泌物中。它也存在于中性粒细胞的次级颗粒中，并在创伤、感染或炎症期间释放到循环系统中。LF属于转铁蛋白家族，即一类能与铁离子高亲和力结合的蛋白质。1961年分离出来时，LF最初被称为一种红色的、结合铁的蛋白质。LF结合铁的能力与其在体内发挥的其他功能相关。如本文第一部分所述，LF参与从食物中获取铁并将其储存于体内，在一定程度上还参与铁向细胞的转运。在本文这一部分中，将描述LF通过螯合铁来对抗微生物的作用。LF的铁螯合特性使病原体无法获取铁，从而限制其生长。由于铁参与许多代谢过程，它是几乎所有微生物的必需元素。在宿主体内，病原体不容易获取铁。由于铁对病原体和宿主的正常功能都至关重要，因此在感染期间获取铁的能力被视为一种重要的毒力因子。高等脊椎动物已经进化出一个复杂的铁储存保护系统，而LF是这个系统的重要组成部分。低铁饱和度的LF以抑菌和抑真菌的方式有效对抗细菌和真菌。铁饱和度的程度也会影响LF的抗病毒活性。一些病原体（如幽门螺杆菌、奈瑟菌属、流感嗜血杆菌）已经进化出一套铁载体或细胞受体系统，能够从LF和转铁蛋白中获取铁。此外，炎症性低铁血症的所谓乳铁蛋白理论认为，该蛋白在炎症、败血症和创伤中具有保护作用。LF通过在肝脏和脾脏中螯合和储存血浆铁，暂时限制微生物对铁的获取以及有毒活性氧的形成过程，这有助于改善炎症状态。
