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PubMed1986

Effects of lactoferrin on human granulopoiesis in vitro.

It has been proposed that Lactoferrin plays a negative feedback role in regulating granulopoiesis through its ability to suppress Colony-Stimulating Factor production. However, an analysis of experimental data, based on cell kinetic principles, does not support this contention. The basic point is that the concentration of Colony-Stimulating Factor determines the rate of clonal amplification, and mean clonal size. The latter is a reliable index with which to quantify the level of stimulation in a system. With this index it was found that Lactoferrin: did not suppress the de novo production of colony factor by blood mononuclear leukocytes affected the rate of cell proliferation both in the absence and presence of preformed Colony-Stimulating Factor. It was also found that Lactoferrin influenced myelocyte progression through the cell cycle. These findings suggest that the action of Lactoferrin is more complex than was previously believed and its relevance as a regulator of granulopoiesis is unclear.

Bone Marrow↗
PubMed1979

Demonstration of lactoferrin in tumor tissue from two patients with positive gallium scans.

We have detected lactoferrin in tumor tissue from a patient with Hodgkin's disease and a patient with Burkitt's lymphoma. Both patients had radiogallium scans demonstrating increased uptake in the tumor tissue subsequently found to contain lactoferrin. Tissue assay for lactoferrin was performed by the indirect immunofluorescence method. Control splenic tissue showed either slight lactoferrin content or none.

Adult↗
PubMedDate not supplied

[Immunochemical and physico-chemical characteristics of lactoferrin in human body fluids].

It is proved that lactoferrins of different human body fluids (sperm, saliva, milk, tears, urine, bile, sweat, liquor, lymph, blood serum) are immunochemically identical. The lactoferrin is purified from milk, saliva and sperm and the identity of physical and chemical properties of lactoferrins of various origins is proved. The quantitative estimation of the contents of this protein in normal body fluids is given. It is detected the dependence of this protein' electrophoretic mobility and isoelectric point of degree of iron saturation. It is found that lactoferrin is capable to form complexes with esterase.

Body Fluids↗
PubMed1983

Plasma lactoferrin reflects granulocyte activation in vivo.

N-formyl-met-leu-phe (FMLP) causes polymorphonuclear leukocytes (PMN) to secrete and become "sticky" in vitro. We related these events to in vivo FMLP-induced neutropenia. FMLP was intravenously administered to anesthetized rabbits in doses ranging from 0.01 microgram to 1.0 microgram. Controls received phosphate-buffered saline (PBS), the diluent for FMLP. Blood pressure, respiratory rate, and arterial Po2 were monitored. High and intermediate doses of FMLP caused a dramatic but transient decrease in blood pressure and an increase in respiratory rate. Prior to FMLP infusion, plasma lactoferrin level was 6.4 +/- 4.1 micrograms/ml, and the absolute granulocyte account (AGC) was 2008 +/- 1229 (mean +/- SD). There was a positive linear correlation between AGC and plasma lactoferrin level prior to injection of FMLP (R2 = 0.74, p less than 0.01). At 1 min after FMLP injection, the percent change in AGC decreased as an exponential function of dose to as low as 10% of baseline (R2 = 0.86, p = 0.002) and plasma concentration of lactoferrin increased as an exponential function of dose to as high as 30 micrograms/ml (R2 = 0.84, p = 0.006). Thus, FMLP-induced neutropenia is associated with increased levels of plasma lactoferrin, suggesting that PMN are induced to degranulate in vivo.

Animals↗
PubMed1983

Lactoferrin in pure pancreatic juice in chronic pancreatitis.

To investigate the role of lactoferrin in intraductal protein precipitates in chronic pancreatitis, lactoferrin was measured in pure pancreatic juice collected by endoscopic retrograde pancreatic cannulation using a sensitive and specific radioimmunoassay. Significant gradual increase in the lactoferrin concentration and output was observed in chronic pancreatitis (mean +/- SE = 1.13 +/- 0.04 microgram/ml, 1.61 +/- 0.44 microgram/min for five controls; 4.73 +/- 0.70 microgram/ml, 14.1 +/- 2.86 micrograms/min for 15 patients with noncalcified mild chronic pancreatitis; 23.6 +/- 4.7 micrograms/ml, 28.4 +/- 13.4 micrograms/min for four with chronic pancreatitis with visible protein plugs or calculi). The total protein in the juice gradually decreased in chronic pancreatitis (12.8 +/- 1.48 mg/ml for control, 7.6 +/- 1.37 for noncalcified, 5.2 +/- 1.27 for patients with plugs or calculi). Lactoferrin appears to rise as the disease progresses and although this may be important etiologically, it may also just be an accompanying protein which increases as the disease progresses.

Adult↗
PubMed1982

Neutropenia induced by systemic infusion of lactoferrin.

Rabbit granulocyte lactoferrin, when infused into hamsters or rabbits, induces transient neutropenia, and in hamsters the lactoferrin promotes adherence of the granulocytes to the endothelial cell wall as monitored visually. In contrast, neither rabbit granule lysozyme nor human transferrin induces neutropenia in the rabbit nor does transferrin or bovine serum albumin affect the adherent properties in vivo of the phagocytic cells of the hamster. Thus lactoferrin enhances granulocyte adherence both in vivo and in vitro. It would appear that the promotion of margination of leukocytes by lactoferrin in vivo may contribute to the phenomenon of neutropenia during activation of granulocytes by chemotactic factors.

Agranulocytosis↗
PubMed1995

Effect of some physical and chemical factors on the bactericidal activity of human lactoferrin and transferrin against Yersinia pseudotuberculosis.

The iron-chelating proteins lactoferrin and transferrin have been shown to be bactericidal for a variety of organisms. In this study, the effect of pH, temperature, their concentration, and magnesium and calcium on the bactericidal activity against Yersinia pseudotuberculosis was investigated. The bactericidal activity of lactoferrin was higher at acid pH, whereas, the bactericidal activity of transferrin was higher at alkaline pH. Both were not efficient at 4 degrees, 15 degrees, and 25 degrees C, but they were efficient at 37 degrees C. Lactoferrin, but not transferrin, was very efficient at 42 degrees C. The activity of both were time and concentration dependent. Calcium did not effect their activity up to 60 mM, whereas, magnesium reduced the activity of lactoferrin only.

Calcium↗
PubMed1996

Neutrophil lactoferrin release induced by IgA immune complexes can be mediated either by Fc alpha receptors or by complement receptors through different pathways.

Our previous results showed that neutrophil secondary granule release, indicated by release of lactoferrin, was a slow process when induced by IgA immune complexes (IC) formed in heat-inactivated serum, but became very fast if IgA IC were formed in normal human serum. This phenomenon did not apply to the IC of other Ab isotypes. In this paper, we demonstrate that the fast lactoferrin release is caused by complement, mainly due to the deposition of C3b and iC3b on IgA IC. Either CR1 or CR3 can mediate the response and both receptors have to be blocked to prevent it. Complement also influences FcalphaR-mediated lactoferrin release, in that this is enhanced by the anaphylatoxin peptides, C5a and C5a(desArg). Divalent cations are required for FcalphaR and CR3- but not for CR1-mediated lactoferrin release. Genistein, a protein tyrosine kinase inhibitor, totally inhibits FcalphaR-mediated response, but has little effect on CR1-mediated response. Therefore, it is clear that different pathways of intracellular signaling are utilized. In addition, stimulation through FcalphaR promotes the receptor up-regulation, which is abolished by the presence of EDTA or genistein.

Antigen-Antibody Complex↗
PubMed1997

Neutrophil activation in preeclampsia. Are defensins and lactoferrin elevated in preeclamptic patients?

OBJECTIVE: To determine if human defensins and lactoferrin, both markers of neutrophil activation, are elevated in preeclamptic plasma. STUDY DESIGN: Blood samples were obtained from 18 preeclamptic and 29 normal pregnant women in the third trimester. Demographic and clinical data were obtained from the medical record. No patient had evidence of labor and/or infection when blood was drawn. Preeclamptic patients were defined by elevated blood pressure, 140/90 mm Hg, proteinuria of > 300 mg in a 24-hour collection and hyperuricemia. Human defensins and lactoferrin were measured by enzyme immunoassay of plasma samples diluted 1:100 and 1:10, respectively. Standard curve values ranged from 0.25 to 16 ng/mL. Data for human defensins and lactoferrin are presented as median values +/-SE. Statistical analysis included Student's t test for comparison of clinical data, Mann-Whitney U test for comparison of absolute values between groups and Fisher's exact test, when appropriate. RESULTS: There was no difference in age or estimated gestational age between the two groups. There were more nulliparous patients in the preeclamptic group. Human defensin levels were significantly elevated (P = .005) in plasma of preeclamptic patients (25.1 ng/mL +/- 16.2) as compared to normal controls (9.0 ng/mL +/- 8.9). Nine of 18 (50%) preeclamptic patients and 2 of 29 (7%) normal controls had defensin levels above the low point on the standard curve (P = .001). There was no difference in lactoferrin levels between the two groups. CONCLUSION: Our results suggest that preeclampsia is associated with neutrophil activation. The biologic effect of elevated human defensins in preeclamptic plasma remains to be determined.

Adult↗
PubMed1998

[Clinico-diagnostic role of ferritin and lactoferrin assays in benign and malignant affections of lungs and pleura].

Immunochemical tests of blood sera from 160 healthy residents of the town of Astrakhan were performed to determine standard quantities of ferritin and lactoferrin in the serum. Examinations of the saliva from 280 healthy subjects provided the frequency of occurrence and levels of excretory lactoferrin. These iron-containing proteins were also assessed in different biosubstrates (blood serum, sputum, saliva, pleural fluid, lung tissues) from 550 patients with benign and malignant lesions of the lungs and pleura. Tests for ferritin and lactoferrin proved useful in evaluation of bronchopulmonary inflammation activity, early detection of pulmonary and intrapleural supputation, differential diagnosis of chronic nonspecific pulmonary diseases and lung cancer. The excretory salivary lactoferrin provided sufficient information on the condition of adaptive mechanisms of local defense of the lungs in premorbid state in 420 workers of the gas-processing plant exposed to aggressive occupational pollutants.

Adult↗
PubMed1998

Three complement-type repeats of the low-density lipoprotein receptor-related protein define a common binding site for RAP, PAI-1, and lactoferrin.

The low-density lipoprotein receptor-related protein (LRP) is a 600-kD scavenger receptor that binds a number of protein ligands with high affinity. Although some ligands do not compete with each other, binding of all is uniformly blocked by the 39-kD receptor-associated protein (RAP). RAP is normally found in the endoplasmic reticulum and seems to function as a chaperone for LRP. To identify the binding sites for RAP, lactoferrin, and plasminogen activator inhibitor-1 (PAI-1), a bacterial expression system has been developed to produce soluble LRP fragments spanning residues 783-1399. These residues overlap most of the CNBr fragment containing the second cluster of complement-type repeats (C). Solid phase binding assays show that 125I-RAP binds to fragments containing three successive complement-type repeats: C5-C7. PAI-1 and lactoferrin bind to the same fragments. A fragment containing C5-C7 also blocks uptake and degradation of 125I-RAP by fibroblasts in a concentration-dependent manner. Binding competition experiments show that RAP, PAI-1, and lactoferrin each inhibit the binding of the others, suggesting that at this site in LRP, RAP acts as a competitive, rather than an allosteric, inhibitor of PAI-1 and lactoferrin binding.

Animals↗
PubMed1969

Lactoferrin, an iron-binding protein in neutrophilic leukocytes.

Lactoferrin, an iron-binding protein previously shown to occur in many external secretions, is identified as one of the major proteins present in human and guinea pig neutrophilic polymorphonuclear leukocytes. The identification of this protein in leukocyte extracts was based upon a comparison of its electrophoretic, antigenic, and iron-combining properties with the corresponding properties of the same protein isolated from human and guinea pig milk. Immunochemical quantitations showed that lactoferrin occurs in human neutrophilic leukocytes at the concentration of 3 microg per 10(6) cells. Tissue cultures from guinea pig bone marrow and spleen actively synthesized the protein, as shown both by net production of lactoferrin and incorporation of labeled amino acids into the protein. Immunohistochemical data indicate that lactoferrin first appears in myeloid cells at the stage of the promyelocyte.

Amino Acids↗
PubMed1984

Lactoferrin receptors in normal and leukaemic human blood cells.

The binding of 125I-lactoferrin to a variety of peripheral blood cells was examined. In the concentration range from 10(-9) mol/l to 10(-6) mol/l a receptor-like binding of lactoferrin was observed in monocytes as well as in polymorphonuclear leucocytes. At the low concentrations of lactoferrin in plasma (about 10(-9) mol/l) the cellular binding to monocytes was about 10 times higher than the binding to polymorphonuclear leucocytes and lymphocytes. A major result from a kinetic analysis was a lower apparent binding affinity to polymorphonuclear leucocytes (KD about 2 X 10(-7) mol/l) than to lymphocytes and monocytes (KD about 2 X 10(-8) mol/l). Studies in leukaemic cells showed that lymphocytes from patients with chronic lymphocytic leukaemia bound lactoferrin to the same small extent as normal lymphocytes. In contrast, a larger component of binding with high affinity (KD about 2 X 10(-8) mol/l) could be demonstrated to lymphoblasts as well as to myeloblasts.

Binding Sites↗
PubMed1989

Ultrastructural localization of DNA on ultrathin sections of resin-embedded tissues by the lactoferrin-gold complex.

Lactoferrin, a DNA-binding protein, was complexed to colloidal gold and applied on ultrathin sections of resin-embedded plant tissues and bacterial cultures. Optimal results were obtained when lactoferrin was tagged to colloidal gold particles at pH 9.2. Postfixation with osmium tetroxide and embedding with Epon did not prevent the accessibility of the protein towards its corresponding binding sites. In plant nuclei, labeling was observed over the dense chromatin and to a lesser extent over the dispersed chromatin. Nucleolar labeling was preferentially located over the dense fibrillar component. Gold particles were also found to be associated with chloroplasts and mitochondria. In prokaryotic cells, a dispersed labeling was noted over the cytoplasm and, in some cases, the aggregation of few gold particles suggested the presence of packed DNA fibrils. Various control experiments confirmed the specificity of the labeling pattern obtained. Lactoferrin-gold complex appears to be a valuable probe for the intracellular demonstration of DNA molecules in double-fixed and Epon-embedded tissues.

Colloids↗
PubMed1998

Lactoferrin markedly inhibits hepatitis C virus infection in cultured human hepatocytes.

We found that bovine lactoferrin (bLF), a milk protein belonging to the iron transporter family, effectively prevented hepatitis C virus (HCV) infection in cultured human hepatocytes (PH5CH8), a cell line susceptible to HCV infection and supportive of HCV replication. Because preincubation of HCV with bLF was required to prevent the infection of HCV to the cells, and preincubation of bLF with the cells showed no inhibitory effect on HCV infection, we demonstrated that the anti-HCV activity of bLF was due to the interaction of bLF with HCV, but not due to the interaction of bLF with the cells. We further found that human lactoferrin also had anti-HCV activity, but bovine transferrin, the other member of the iron transporter family, did not have anti-HCV activity. Our findings suggest that lactoferrin is one of candidates for an anti-HCV reagent that will be well-tolerated and effective in the treatment of patients with chronic hepatitis.

Animals↗
PubMed2001

Protective role of human lactoferrin against invasion of Shigella flexneri M90T.

Lactoferrin is an iron-binding protein found in human mucosal secretions such as milk. A variety of functions have been ascribed to this protein, it appears to contribute to antimicrobial host defense. Still its overall physiological role remains to be defined. We sought to study the role of recombinant human lactoferrin (rhLf) in Shigella infection. Invasion of epithelial cells is essential to the development of bacillary dysentery. Shigella flexneri 5 M90T, a virulent strain, was evaluated in the classic HeLa cell invasion model, in immunoblots, and by transmission electron microscopy, immunofluorescence, and deconvolved microscopy Bacteria not exposed to rhLf were used as controls. We found that rhLf decreased significantly the invasiveness of S. flexneri 5 M90T in a HeLa cell model. The immunoblot data showed that invasion plasmid antigen B (IpaB) was released from the bacteria during incubation with rhLf. Lactoferrin treatment did not directly dissociate the complex of IpaB and IpaC (IpaBC) once the complex had been formed. Furthermore, ferric iron had no effect on release of IpaB. Electron microscopy of rhLf-treated bacteria suggested a reduction in vacuolization of the HeLa cell cytoplasm and decreased number of bacteria within HeLa cells. At 40,000 x magnification the few rhLf-treated Shigella that invaded exhibited a dense ring completely surrounding them. Immunofluorescence and deconvolved microscopy suggested that rhLf-treated bacteria were completely surrounded by a thick layer of actin. The fact that two cell surface functions (invasion and actin-mediated movement) were deranged suggests that rhLf disrupts the integrity of the bacterial outer membrane in which virulence proteins are anchored. The mechanism by which rhLf impairs Shigella invasiveness may be relevant to other enteropathogens that share similar virulence strategies.

Blotting, Western↗
PubMed1994

Tear lactoferrin levels and ocular bacterial flora in HIV positive patients.

Keratoconjunctivitis Sicca(4) has recently been reported to occur at a greater rate in HIV-positive symptomatic patients. We looked at HIV positive asymptomatic patients, compared to age matched HIV negative patients to study external ocular resistant factors, namely lactoferrin levels in tears, bacterial flora in lid margins, conjunctiva and tears, and evidence of dry eyes using a Schirmer test and tear osmolarity. Eighteen eyes of nine HIV positive patients and eighteen eyes of HIV negative controls were studied. Results showed markedly decreased lactoferrin levels in HIV positive asymptomatic patients with a mean of 85.8 mgs/dcl compared to HIV negative patients with a mean 156 mgs/dcl (P < 0.01). There were increased numbers of colonies of bacterial flora on the lids of HIV positive asymptomatic patients with an average colony count 4.1 colonies/patient compared to 1.5 colonies/patients in the control group (P < 0.025). Seventy eight percent of the study group had bacterial growth compared to 33% in the control group. The tear osmolarity in both groups had no significant difference; mean in HIV positive being 312 mosml/litre; mean in control 306 mosml/litre. The Schirmer test also showed no significant difference, with the mean in HIV positive patients being 11 mm wetting, and in control patients being 12.7 mm wetting. Therefore, despite no symptomatic or clinical evidence of dry eyes, asymptomatic HIV-positive patients had markedly decreased levels of lactoferrin in tears and increased colony counts of bacterial flora in the lids.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Immunohistochemical demonstration of lactoferrin in follicular adenomas and thyroid carcinomas.

By immunohistochemistry, the presence of lactoferrin was investigated in follicular adenomas (10 cases) and carcinomas of the thyroid gland (23 cases). Normal thyroid tissue was also tested as control. Follicular adenomas showed a consistent negativity, whereas follicular and papillary carcinomas exhibited various degrees of positivity for lactoferrin. Incorporated organoid structures observed in anaplastic carcinomas were strongly stained; the spindle cell parts of these cancers were always negative for this iron-binding protein. Medullary carcinomas were also unstained. These findings are discussed in relation to the distribution pattern of thyroglobulin. The authors emphasize the possibility that lactoferrin may be useful in clarifying some diagnostic problems in neoplastic thyroid pathology.

Adenoma↗