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PubMed1983

Non-specific binding of transferrin and lactoferrin to polystyrene culture tubes: role of the radioligand.

While evaluating the role of iron-binding glycoproteins on the in vitro uptake of 67Ga and 59Fe by tumor cells, it was observed that these radiometals bind to polystyrene culture tubes in the presence of transferrin or lactoferrin. The amount of 67Ga or 59Fe bound to the tube increases with glycoprotein concentrations up to 20 microgram/ml and decreases thereafter. This biphasic response is a reflection of metal-protein affinity and is greatest for 59Fe-lactoferrin. With 125I-labeled transferrin and lactoferrin, the amount of tube-bound radioactivity was inversely dependent on the glycoprotein concentration suggesting that glycoproteins bind to a limited number of binding sites on the tube wall. Approximately 10(13) glycoprotein molecules were bound per tube with an affinity constant of 1.89 X 10(7) 1/M for transferrin and 1.08 X 10(7) l/M for lactoferrin. These sites are not specific since addition of albumin inhibited the binding of radiolabeled glycoproteins to the tube. In the light of these observations, caution is required in interpreting results of cell culture experiments which have not directed attention to protein-plastic interaction.

Albumins↗

PubMed1981

Lactoferrin and lysozyme in carcinomas of the parotid gland. A comparative immunocytochemical study with the occurrence in normal and inflamed tissue.

Lactoferrin and lysozyme, parts of the non-specific defense system, were studied in normal and diseased parotid glands, using the immunohistochemical PAP-method. 31 normal and inflamed glands were investigated. The presence of lactoferrin and lysozyme was demonstrated in the acinar cells and some duct cells. The amount of these substances was increased in obstructive parotitis. The 52 carcinomas showed a distinct distribution pattern for lactoferrin (positive cases: adenocarcinomas 5 of 8; cystadenocarcinoma: 3 of 5; adenoid cystic carcinomas 2 of 4; salivary duct carcinomas 2 of 3). Some of the carcinomas in pleomorphic adenomas were positive for lactoferrin. Squamous cell carcinomas and anaplastic carcinomas were constantly negative. All carcinomas were negative for lysozyme. These observations are discussed with respect to their physiological and pathological significance.

Adenocarcinoma↗

PubMed1980

Lactoferrin and albumin in human pancreatic juice: a valuable test for diagnosis of pancreatic diseases.

Lactoferrin and albumin concentrations in pure pancreatic juice were studied by radial immunodiffusion in 81 patients. Lactoferrin concentration (% of total protein) was specifically increased in patients suffering from chronic calcifying pancreatitis (mean +/- SE: 0.169 +/- 0.024) and no overlap was observed with patients suffering from other pancreatic diseases (0.008 +/- 0.001), organic nonpancreatic diseases (0.011 +/- 0.001) and without organic disease (0.01 +/- 0.001). Lactoferrin concentration was not found to be correlated with chronic alcohol consumption or pancreatic insufficiency. Albumin concentration (% of total protein) was increased in patients suffering from chronic calcifying pancreatitis (5.55 +/- 0.49) and other pancreatic diseases (5.45 +/- 1.02). These values were significantly higher (P less than 0.001) than the corresponding values in patients with organic nonpancreatic diseases (1.66 +/- 0.16) and patients without organic diseases (1.46 +/- 0.22). Measuring lactoferrin and albumin in pancreatic juice may aid in the diagnosis of pancreatic disease and in the differentiation of chronic calcifying pancreatitis, even in the earliest stage, from other pancreatic diseases such as pancreatic carcinoma or acute pancreatitis.

Adult↗

PubMed1983

A simple test for lacrimal gland function: a tear lactoferrin assay by radial immunodiffusion.

A radial immunodiffusion assay for tear lactoferrin is described. Tear samples, collected on filter paper discs, could be applied directly to immunodiffusion plates after blotting. In 58 tear samples from healthy subjects an average lactoferrin concentration of 1.42 g/l was found. A high degree of correlation was found between the lactoferrin radial immunodiffusion and the lysozyme agar diffusion assay in a heterogeneous group, ranging from healthy subjects to patients with severe keratoconjunctivitis sicca. A lower limit of normal (0.78 g/l) could be determined for the tear lactoferrin concentration. The assay does not require laboratory facilities and therefore is an easily accessible alternative for or an addition to lacrimal gland function tests currently used.

Humans↗

PubMed1991

Lactoferrin and secretory IgA in the bronchoalveolar lavage fluid from patients with a stable asthma.

We have measured lactoferrin and secretory IgA (sIgA) in the unconcentrated bronchoalveolar lavage fluid (BALF) from nonsmoking healthy volunteers (n = 10) and nonsmoking patients with stable asthma (n = 14). The median concentrations and the ranges of lactoferrin were controls, 0.13 mg/L (0.01-0.43 mg/L); asthma, 0.41 mg/L (0.07-7.51 mg/L). For sIgA the results were controls, 0.48 mg/L (0.12-1.47 mg/L); asthma, 1.29 mg/L (0.65-14.6 mg/L). The concentrations in the epithelial lining fluid (ELF) were calculated on the basis of urea in BALF and serum. SIgA and lactoferrin levels in the BALF and ELF from the patients with asthma were higher than in controls (Mann-Whitney U-test, p less than 0.03). Our results indicate that in patients with stable asthma the airway epithelial cells are activated, resulting in an enhanced secretion of lactoferrin and enhanced secretory transport of sIgA into the airway lumen.

Adolescent↗

PubMed1998

[Heterogeneity of seminal vesicle amyloid. Immunohistochemical detection of lactoferrin and amyloid of the prealbumin-transthyretin type].

Localized depositions of amyloid in the seminal vesicles may occur in elderly men. Earlier immunohistochemical studies have failed to identify immunoreactivity of known amyloid material. In this autopsy study, all seminal vesicles of males older than 50 years were histologically examined to determine incidence and phenotype of seminal vesicle amyloidosis. Seven out of 50 patients (14%) showed depositions of amyloid in the seminal vesicles. These amyloid depositions as well as one additional case were characterized histochemically, immunohistochemically and electronmicroscopically. All but two of these patients (75%) showed simultaneously amyloid depositions in the heart. Lactoferrin immunoreactivity was found in 6 patients (75%). Lactoferrin is an iron-binding, bacteriostatic glycoprotein, which is produced in the seminal vesicles. Four patients with lactoferrin positive amyloid in seminal vesicle showed different amyloid depositions in the heart (immunoglobulin light chain amyloid AL-lambda). Two cases (25%) showed the same amyloid type in heart and seminal vesicles (prealbumin-transthyretin type amyloid). Our study shows that most amyloidoses of the seminal vesicles are organ-limited depositions of lactoferrin. These forms of localized amyloidosis have to be separated from senile systemic amyloidosis with seminal vesicle involvement.

Aged↗

PubMed2006

Molecular cloning and expression of yak (Bos grunniens) lactoferrin cDNA in Pichia pastoris.

cDNA encoding lactoferrin from yak was isolated by RT-PCR and then sequenced. The cloned cDNA (2127 bp) encodes a 709 amino acid precursor molecule of yak lactoferrin with a signal peptide of 19 amino acids. The yak lactoferrin cDNA was expressed in Pichia pastoris. The recombinant protein, purified by Ni-NTA affinity column, had a molecular weight of 76 kDa and reacted with an antibody raised against native bovine lactoferrin. The iron-binding behavior and antimicrobial activity of the purified protein indicated that it was correctly folded and functional.

Amino Acid Sequence↗

PubMed1989

Different segmental flexibility of human serum transferrin and lactoferrin.

X-ray diffraction studies show that the diferric (holo) forms of human serum transferrin and lactoferrin have almost the same conformation in crystal. In solution, however, the two proteins exhibit different characteristics. The differences are even more pronounced in the apo forms. Small-angle X-ray and neutron scattering data show that lactoferrin is less compact, in apo and holo forms, than the corresponding forms of transferrin in solution. The comparison of primary structures of the two proteins suggests that one of the interdomain hinge regions is significantly longer in lactoferrin than its counterpart in transferrin. The difference in flexibility due to the long hinge region in lactoferrin may be responsible for many of the differences in the physicochemical characteristics of the two proteins.

Humans↗

PubMed1994

The effect of antifungal agents on the in vitro susceptibility of Candida albicans to apo-lactoferrin.

The effect of subminimal inhibitory concentrations (MICs) of nystatin, amphotericin B, clotrimazole, miconazole and 5-fluorocytosine on the in vitro susceptibility of Candida albicans to physiological concentrations of apo-lactoferrin was investigated. Pre-exposure of C. albicans in 1:4 and 1:16 MICs of the antifungals resulted in an increased resistance to apo-lactoferrin-mediated cell death. Preincubation of Candida in tunicamycin (an agent that inhibits the synthesis of yeast cell-wall mannoproteins) and subsequent exposure to apo-lactoferrin enhanced the antifungal activity, whilst addition of ergosterol (a yeast cell-wall component) to the assay suspension had no significant effect. These results taken together indicate that apo-lactoferrin, an important component of saliva, interacts with cell-membrane constituents of C. albicans such as mannoproteins, and may modulate the effect of topical antifungal agents commonly prescribed for oral candidoses.

Amphotericin B↗

PubMed1986

Isolation and characterisation of lactoferrin separated from human whey by adsorption chromatography using Cibacron Blue F3G-A linked affinity adsorbent.

A new one-step procedure for isolating lactoferrin from human whey using Cibacron Blue affinity chromatography is described. Characteristics of the isolated lactoferrin include pI 5.5-6.1 and differential migration on SDS-polyacrylamide gel electrophoresis of apo and iron saturated lactoferrin. The concentration of lactoferrin in breast milk varies with time after parturition but the iron saturation remains relatively constant with time.

Chromatography, Affinity↗

PubMed1987

Plasmodium falciparum: inhibition in vitro with lactoferrin, desferriferrithiocin, and desferricrocin.

The microbial iron chelators desferriferrithiocin and desferricrocin as well as human lactoferrin were tested in vitro against Plasmodium falciparum. The microbial chelators inhibit the growth of P. falciparum in a dose dependent way. Parasite multiplication is stopped at 25-30 microM desferriferrithiocin, whereas 60-90 microM desferricrocin are needed to exhibit the same effect. After iron saturation, the microbial chelators are ineffective. Human lactoferrin (30 microM), both iron free and iron saturated, inhibits P. falciparum. A 3-day preincubation of host erythrocytes with iron free and iron saturated lactoferrin prior to infection enhances this effect, which is therefore attributed to lactoferrin bound iron. It has been suggested that the lactoferrin/iron complex generates oxygen free radicals, which may cause membrane damage of both erythrocyte and parasite. This process can be considered to lead to growth inhibition of the parasite.

Animals↗

PubMed1983

Lactoferrin binding to neutrophilic polymorphonuclear leucocytes.

Neutrophilic polymorphonuclear leukocytes (PMN) bind specifically lactoferrin. This binding was characterized by two types of binding sites: with higher affinity and low capacity and another site with lower affinity and higher capacity (respectively Kaff 1 = 2.2 X 10(9) M-1 and about 39,000 binding sites per cell and Kaff2 = 0.6 X 10(9) M-1 and 76,000 binding sites per cell). The lactoferrin binding to PMN leucocytes depends on the concentration of labelled lactoferrin, the number of cells and the time for incubation. The presence of lactoferrin receptors on the PMN leucocytes is connected most probably with its effect on the cell function of these cells.

Binding Sites↗

PubMed1991

Preliminary crystallographic studies of copper(II)- and oxalate-substituted human lactoferrin.

As part of a comparative study on the binding of different metals and anions by human lactoferrin, we have prepared and crystallized: (1) dicupric lactoferrin with Cu2+ and carbonate in each site (Cu2Lf); and (2) a lactoferrin complex with Cu2+ and carbonate in one site, and Cu2+ and oxalate in the other (Cu2oxLf). Crystals of Cu2Lf are orthorhombic: a = 155.9, b = 97.0, c = 56.0 A, space-group P2(1)2(1)2(1); those of Cu2oxLf are also orthorhombici a = 155.9, b = 97.1, c = 56.2 A, space-group P2(1)2(1)2(1). Both are isomorphous with diferric human lactoferrin, Fe2Lf. Diffractometer data to 2.6 A and 2.5 A have been collected for Cu2Lf and Cu2oxLf, respectively. Difference maps show that the main effect of substitution of Cu2+ for Fe3+ is a small shift (0.5 to 1.0 A) in the metal position in each site. For Cu2oxLf the oxalate ion is found to be accommodated in the C-lobe, bound to copper in a bidentate mode, causing only small local changes, in the positions of adjacent Arg and Tyr side-chains.

Binding Sites↗

PubMed1990

Interaction of bovine lactoferrin with other proteins of milk whey.

The association between bovine lactoferrin and the major bovine whey proteins, beta-lactoglobulin, alpha-lactalbumin and albumin has been studied by immunochemical techniques, gel filtration and affinity chromatography in lacteal secretions and using purified proteins. Bovine lactoferrin is able to form non-covalent complexes with beta-lactoglobulin or albumin, with lactoferrin-protein molar ratios of 2:1 and 1:1 respectively. No association was detected with alpha-lactalbumin. Lactoferrin interacts with beta-lactoglobulin-Sepharose at low ionic strength, but not in the presence of 0.3 M NaCl, indicating that ionic interactions are important. The lack of association with alpha-lactalbumin suggests however a certain degree of specificity in this electrostatic interaction.

Albumins↗

PubMed1985

The interaction between human pancreatic carboxylester hydrolase (bile-salt-stimulated lipase of human milk) and lactoferrin.

An interaction between lactoferrin and human pancreatic carboxylester hydrolase (carboxylic-ester hydrolase, EC 3.1.1.1) (of bile-salt-stimulated lipase from human milk) has been demonstrated using partition in an aqueous two-phase system. This binding was strongly increased by the presence of sodium taurocholate, giving an apparent dissociation constant of around 10(-7) M. With this constant, significant binding is expected to occur in the intestine of the newborn being breast-fed between lactoferrin and either the pancreatic carboxylester hydrolase or the milk bile-salt-stimulated lipase. For carboxylester hydrolase, the interaction with lactoferrin meant a 1.4-fold increase in hydrolytic activity against p-nitrophenylacetate and cholesterololeate. For the function of lactoferrin we have not studied the importance of this interaction.

Bile Acids and Salts↗

PubMed1994

Further evidence of different lactoferrin and transferrin binding sites on human HT29-D4 cells. Effects of lysozyme, fucose and cathepsin G. Comparison with transferrin.

We have defined by using competition experiments the nature of specific lactoferrin binding sites, probably responsible for the previously observed stimulatory growth effect of the iron binding protein on HT29-D4 cells. Lysozyme, albumin and fucose do not affect lactoferrin binding showing that the binding of the protein is mediated neither by electrostatic forces nor by fucose. Iron-free and iron-loaded protein produce similar effects, demonstrating that the metal is not involved in the protein recognition. Similar results are observed for transferrin. A specific binding inhibition of lactoferrin by cathepsin G, a leukocyte proteinase, is observed, suggesting the existence of a common receptor for lactoferrin and cathepsin G on HT29-D4 cells. These results and the fact that tumor tissues are more often infiltrated by inflammatory cells such as polymorphonuclear leukocytes could evoke an unexpected role for leukocytes, possibly mediated in part by these two proteins, on the proliferative cancer effect.

Binding Sites↗

PubMed1992

High-performance liquid chromatographic separation of human apolactoferrin and monoferric and diferric lactoferrins.

A simple chromatographic separation of the different molecular forms of human milk lactoferrin according to their iron contents is described. The appropriate conditions were developed with a Mono-S cation-exchange column linked to an automated Urtrochrom GTi system. The pure lactoferrin with different iron binding (apolactoferrin, monoferric lactoferrin and diferric lactoferrin) separated into three peaks. The three peaks were eluted from the Mono-S column with 0.88, 0.97 and 1.05 M sodium chloride in 10 mM phosphate buffer (pH 7.0).

Apoproteins↗

PubMed1987

The acquisition of human lactoferrin by Mycoplasma pneumoniae.

We tested the in vitro binding of human iron-sequestering lactoferrin and transferrin by the mucosal-surface pathogens, Mycoplasma pneumoniae and Mycoplasma genitalium. Mycoplasma pneumoniae bound lactoferrin, but not transferrin, in a saturable and specific manner. Analysis of binding data indicates less than 10,000 lactoferrin receptors per micro-organism with a moderately high binding affinity of 20 nM. No significant binding of lactoferrin or transferrin by M. genitalium was observed.

Binding, Competitive↗