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PubMed1984

[Receptors for lactoferrin on human thymic lymphocytes. The stimulation of expression as affected by adenosine, theophylline and a supernatant of thymic lymphocytes].

It was established by indirect immunofluorescence with the use of antibodies to human lactoferrin that thymic lymphocytes bear lactoferrin receptors in the point structures on the cell surface. The ability of thymic lymphocytes to express lactoferrin receptors depends on the cAMP concentration in the cell, inasmuch the treatment of lymphocytes with adenosine and theophylline increases the number of cells bearing lactoferrin receptors. Supernatant of thymic lymphocytes is also capable of stimulating expression of lactoferrin receptors. It is assumed that these treatments can be used for increasing the number of lymphocytes with lactoferrin receptors with the purpose of separation and study of the function of this subpopulation in health and in different pathological conditions.

Adenosine↗

PubMed1983

[Immunochemical determination of human lactoferrin].

The immunochemically pure preparation of lactoferrin was isolated from human colostrum and used for the immunization of animals with a view of obtaining antiserum, and also as a reference preparation for the determination of the content of lactoferrin in the standard. The monospecific antiserum to lactoferrin, obtained as the result of this procedure, was used for the determination of the content of lactoferrin in samples of human milk by the method of radial immunodiffusion. Through the content of lactoferrin in human milk showed considerable fluctuations, its level essentially decreased on the second week of lactation. In cases of the microbial contamination of milk the tendency towards an increase in the content of lactoferrin was observed irrespective of the time of lactation.

Animals↗

PubMed1984

Lactoferrin in pure pancreatic juice.

Lactoferrin as assayed by a radial immunodiffusion technique was studied in pure pancreatic juice collected at endoscopic retrograde cholangiopancreatography from 23 patients with chronic pancreatitis, 12 with acute pancreatitis, 21 with pancreatic cancer, and 29 cases of nonpancreatic gastrointestinal disease. No clear difference between lactoferrin concentrations in the chronic pancreatitis patients and other groups was found. Moreover, most lactoferrin levels were below the limit of detection in our assay. In addition, lactoferrin total protein ratios did not appear to be of value in the differential diagnosis of chronic pancreatitis. These results seem to be in contrast to the findings of other authors, who measured lactoferrin in duodenal fluid--which is unreliable, in our opinion--or who mainly studied chronic pancreatitis patients and few other pancreatic diseases. Lactoferrin might well be a nonspecific marker for serious pancreatic inflammation.

Acute Disease↗

PubMed1982

Ultrastructural localization of lactoferrin and iron-binding protein in human neutrophils and rabbit heterophils.

Lactoferrin in marrow and blood granulocytes from rabbits and humans was stained with an immunoferritin method. Iron-binding protein(s) was localized by the staining of granulocytes with acid ferrocyanide after saturation of the iron-binding protein with iron. The latter was most readily accomplished by treatment of the glutaraldehyde-fixed cell suspension with 1% saponin, followed by treatment with an iron-nitrilotriacetate (Fe-NTA 3mM:4mM) solution, adjusted to pH 7.0 with NaHCO3. The affinity of purified lactoferrin and transferrin for radioiron after such treatment was minimally diminished. Both immunoferritin and iron-binding methods heavily stained osmiophiliuc (phospholipid-containing) mature primary granules in late promyelocytes, myelocytes, and polymorphonuclear cells. Early promyelocytes containing abundant immature primary granules lacked immunoferritin or iron staining. Trypsin digestion of rabbit marrow cells considerably diminished the cytochemically demonstrable iron-binding capability of the mature primary granules. Specimens sequentially stained for peroxidase and immunostained for lactoferrin or cytochemically stained for iron-binding protein confirmed that lactoferrin and iron-binding protein were in peroxidase-positive primary granules. Some peroxidase positive granules appeared to lack staining for lactoferrin and iron-binding proteining protein, and all secondary granules uniformly lacked staining. Treatment of human neutrophils with phorbol myristate acetate demonstrated early release of granules containing iron-binding protein with subsequent agglutination of neutrophils and attachment of iron-binding protein to the cell surface. In summary, this study distinguishes at least two subpopulations of primary granules and identifies lactoferrin and an iron-binding protein(s) in a subpopulation of peroxidase-positive primary granules in rabbit heterophils and human neutrophils.

Animals↗

PubMed1981

Lactoferrin: a promoter of polymorphonuclear leukocyte adhesiveness.

Polymorphonuclear leukocytes (PMN) degranulate, adhere to vascular endothelium, or aggregate to each other following exposure of the cells to high concentrations of chemotactic stimuli such as formyl-methionyl-leucyl phenylalanine (FMLP). PMN released the specific granule product lactoferrin more readily in response to chemotactic stimuli, which correlated with promotion of PMN aggregation as measured by light transmission and enhanced PMN adherence. Both concanavalin A (Con-A) and phorbol myristate acetate (PMA), agents that lead to specific granule discharge, induced and sustained human PMN aggregation. Similarly, supernatants, generated from Con-A-treated PMN, aggregated fresh PMN in the presence of alpha-methylmannoside, a competitive inhibitor of the lectin. Anti-human lactoferrin IgG but not normal goat IgG blunted the aggregation elicited by both PMA and FMLP. Both human milk lactoferrin and rabbit PMN lactoferrin aggregated human lactoferrin promoted PMN adherence to endothelial cells. The enhanced PMN stickiness was correlated with the early phase of degranulation. Thus, PMN lactoferrin serves an autoregulatory role to retain PMN at inflammatory sites to amplify the inflammatory response.

Animals↗

PubMed1995

Impairment of circulating lactoferrin in HIV-1 infection.

Levels of plasma lactoferrin are decreased in HIV-1-infected patients in relation to the progression of the disease. Plasma lactoferrin concentrations were determined using a specific and sensitive enzyme immunoassay. 97 plasma were studied (22 asymptomatic, 45 symptomatic patients compared to 30 healthy controls) and the results showed a highly significant decrease (p < 0.001) of the level of lactoferrin in HIV-1-infected patients (respectively 2.79 +/- 1.2 and 0.68 +/- 0.22 micrograms/ml) compared to controls (4.37 +/- 0.83 micrograms/ml). Since it is well established that plasma lactoferrin level could be influenced by the number of neutrophils, the experiments were reproduced in neutropenic patients who represent 10% of recruitment (6 among 45 symptomatic patients). The plasma from neutropenic symptomatic patients (neutrophils < or = 1,300/mm3) showed their mean lactoferrin level at 0.36 micrograms/ml still far above the normal values. In view of the different reported biological effects of lactoferrin that are of great importance in the non-specific defences, the real biological place of the lack of such a molecule could be one important component of the multifactorial nature of HIV-1 infection.

AIDS-Related Complex↗

PubMed1993

Isolation and characterization of porcine milk lactoferrin.

We purified porcine whey lactoferrin by affinity chromatography on a heparin-Sepharose column, followed by high-performance liquid chromatography. Molecular mass of purified lactoferrin (PLF) is 78,000 daltons. The iron-binding activity of PLF had a UV/visible-light absorption spectrum indistinguishable from that of human and bovine lactoferrins (absorbance ratio [465 nm/280 nm] approx 0.046). The growth ratio of WIL-2 cells in PLF-supplemented medium is 70% of that in serum-containing medium. The aforementioned characteristics are similar to those of human and bovine lactoferrins. Immunoblot analysis, using polyclonal antibody raised in rabbits against porcine whey lactoferrin, revealed high specificity for PLF, and low cross-reactivity with commercial human and bovine lactoferrins.

Animals↗

PubMed1997

The antifungal effect of lactoferrin and lysozyme on Candida krusei and Candida albicans.

Lactoferrin and lysozyme (muramidase) are non-immune defence factors present in various exocrine secretions, including saliva. Previous studies have shown that both proteins, either singly or in combination, are bactericidal in nature and their combined activity is synergistic. As little is known of their interactions with Candida species, 20 oral isolates of C. krusei and 5 isolates of C. albicans were studied for their susceptibility to human apo-lactoferrin and lysozyme, either singly or in combination, using an in vitro assay system. The two species exhibited significant interspecies differences in susceptibility to lactoferrin (p < 0.05), but not for lysozyme; C. krusei being more sensitive to lactoferrin (c 1.4 times) than C. albicans. Both species revealed significant intraspecies differences in their susceptibility to lysozyme (p < 0.05), but not for lactoferrin. No synergistic antifungal activity of the two proteins on either Candida species was noted. The results imply that the variable expression of the fungicidal activity of lactoferrin and lysozyme on Candida species may modulate the oral carriage of yeasts in a complex manner.

Antifungal Agents↗

PubMed1998

Lactoferrin effects on the in vitro immune response in critically ill patients.

The aim of the study was to investigate whether lactoferrin can improve the immune competence of cells from patients with systemic inflammatory response syndrome (SIRS). We studied the effect of lactoferrin (LF) on the proliferative response of peripheral blood mononuclear cells (PBMC) to lipopolisaccharide (LPS) in vitro and its influence on production of 2 proinflammatory cytokines: interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). Three groups of patients: septic survivors, septic nonsurvivors and multiple trauma patients, were investigated. Blood samples were taken upon admission to intensive care unit and after 2, 3 and 5 days. The proliferative response of PBMC in vitro was tested using 3-day culture with LPS. Cell proliferation/death was measured using MTT colorimetric method. The spontaneous and LPS-induced activity of TNF-alpha and IL-6 were measured with bioassays using indicator cell lines WEHI-164.13 and 7TD1, respectively. We demonstrated that LF inhibited the proliferative response, both spontaneous and LPS-induced, in all groups of patients. Lactoferrin alone was a good inducer of IL-6 and TNF-alpha production by monoclear cells in vitro. Addition of LF to the cultures of LPS-activated mononuclear cells stimulated IL-6 production, most markedly in the group of septic survivor patients (mean 1479, 1452, 1728, 1980 pg/ml on day 1, 2, 3 and 6 respectively). Lactoferrin also upregulated TNF-alpha production. That effect was very significant in the septic survivor patients (mean 7407, 6739, 7498 and 8509 pg/ml on day 1, 2, 3 and 5 respectively) and less pronounced in the group of trauma patients. We conclude that lactoferrin exhibited regulatory actions on the altered reactivity of PBMC from patients with sepsis and multiple injury. Lactoferrin is a good inducer of IL-6 and TNF-alpha production. However, in most cases of septic nonsurvivors LF could not abolish low reactivity of cells with regard to cytokine production.

Adolescent↗

PubMed1998

Mouse lactoferrin gene. Promoter-specific regulation by EGF and cDNA cloning of the EGF-response-element binding protein.

Expression of the lactoferrin gene in a variety of tissues is regulated differentially. We have previously demonstrated that the lactoferrin gene is regulated by estrogen and mitogen in mouse uterus. The mouse lactoferrin gene responded to forskolin, cAMP, TPA and EGF stimulation via two adjacent enhancer elements, the CRE and EGFRE and collectively referred to as the Mitogen Response Unit (MRU). We found that CRE is responsible for forskolin, cAMP and TPA whereas EGFRE is for EGF stimulation. We examined the minimal promoter and enhancer elements of the mouse lactoferrin gene that are required for EGF induced transcriptional activation. We found that the CRE and noncanonical TATA box (ATAAA) are the minimal promoter elements for basal activity of the CAT reporter construct, whereas, the EGFRE is needed for an additional activity induced by EGF in transiently transfected human endometrial carcinoma RL95-2 cells (RL95-2). The EGFRE, however, did not function in heterologous promoters (SV 40 and TK). Therefore, EGF-stimulated lactoferrin gene activity is promoter specific in RL95-2 cells. Mutation made at either elements or insertion of extra nucleotides between the two elements, severely affected EGF-stimulated activity. Nuclear protein prepared from RL95-2 cells protected the EGFRE, CRE and noncanonical TATA from DNAase I digestion in a footprinting analysis. Nuclear protein which interacted with the CRE were previously identified as API and CREB. In this study, we isolated a cDNA clone from an RL95-2 expression library that encodes the EGFRE binding protein. Partial sequence of the cDNA clone revealed 100% nucleotide identity with a GC-box binding protein, BTEB2. Protein-protein interaction among the transcription factors could fine-tune the mouse lactoferrin expression in various tissues.

Animals↗

PubMed1994

Evaluation of a New Latex Agglutination Test for Fecal Lactoferrin in Travelers' Diarrhea.

The detection and diagnosis of travelers' diarrhea by fecal culture method, often insensitive, expensive, and time consuming, could well be replaced with the latex agglutination test to detect fecal lactoferrin. As an initial screening, this test could be useful to differentiate between those patients who are more likely to have an invasive enteropathogen and those patients requiring antidiarrheal chemotherapy only. Fecal samples from 92 patients with travelers' diarrhea were tested for occult blood, fecal leukocytes, and fecal lactoferrin at stool dilutions of 1:50 and 1:200. The results were compared with findings from fecal cultures for enteropathogens. Statistical analyses were performed measuring the performance of the latex agglutination test for fecal lactoferrin to calculate its sensitivity, specificity, and positive and negative predictive values. Invasive pathogens were identified in 36 (39%), and a noninvasive pathogen was found in 18, or 20%, of the cases. At the stool dilution of 1:50, fecal lactoferrin showed more sensitivity than did leukocytes or occult blood in detecting the presence of invasive enteropathogens and, with a negative predictive value of 94%, was superior in predicting their absence. At the 1:200 dilution, a lower sensitivity of 55%, but a higher specificity of 82%, compared to 55% with the 1:50 dilution, was demonstrated. The determination of fecal lactoferrin might prove to be more useful and less expensive and time consuming as an initial screening for patients presenting with travelers' diarrhea. Further evaluation and antibacterial treatment could, therefore, be reserved for those with a positive lactoferrin test.

Journal Article↗

PubMed1998

Expression of Human Lactoferrin cDNA in Insect Cells.

A transfer plasmid p8hLFc harboring human lactoferrin cDNA was constructed and co-transfected with Autographa californica nuclear polyhedrosis virus ( AcNPV BacPAK6 ) DNA into Spodoptera frugiperda (Sf) cells. The recombinant virus AcNPV-hLFc was identified and purified three times by dot hybridization and plaques screening. The expression of human lactoferrin cDNA in insect cells was detected by Western blotting. The expression level of lactoferrin is about 2% of insect cellular total soluble proteins, and an amount of 9.5 mg/L lactoferrin is secreted into culture medium. Recombinant lactoferrin purified with affinity chromatography comigrates with human milk lactoferrin on SDS-polyacrylamide gels. In addition, the ration of A value at ultraviolet A(280)/A(465) shows that the recombinant protein possesses iron-binding capacity.

Journal Article↗

PubMed1999

Effect of lactoferrin on the production of tumor necrosis factor-alpha and nitric oxide.

One of the biological functions of lactoferrin is the modulation of the host defense systems, including cytokine production and immune responses. We have tested the effect of lactoferrin on the productions of tumor necrosis factor-alpha and nitric oxide in some cells. Lactoferrin itself did not induce either tumor necrosis factor-alpha production or nitric oxide production, but lipopolysaccharide-stimulated tumor necrosis factor-alpha production of macrophages and monocytes were inhibited by lactoferrin treatment combined with stimulant. The induction of nitric oxide synthesis in stimulated macrophages and vascular smooth muscle cells was not affected by the lactoferrin.

Animals↗

PubMed1985

Localization of lactoferrin and nonspecific cross-reacting antigen in human breast carcinomas. An immunohistochemical study using the avidin-biotin-peroxidase complex method.

A retrospective immunocytochemical study was performed on 67 human breast carcinomas to determine whether the epithelial cell-associated antigens, lactoferrin and nonspecific cross-reacting antigen (NCA), could be used as markers in the prognostic assessment of breast cancers. Fixed paraffin sections were tested with anti-lactoferrin and anti-NCA. Lactoferrin and NCA were found in 7.5% and 19% of the cases, respectively. Furthermore, the association between these two antigens in tumor cells was significant (P less than 0.05). Kappa-casein was observed in all antigen-positive cases. These antigens were observed more often in low-grade ductal carcinomas that had positive estrogen and progestin receptors, but no relationship could be established between lactoferrin or NCA and other prognostic indicators, such as histologic type and grade of the tumor, stromal elastosis, or steroid receptors. Although more antigen might have been detected in unfixed, frozen specimens, the results indicate that lactoferrin and NCA possess minimal value as epithelial cell markers and no prognostic value when detected on routinely fixed, paraffin-embedded samples.

Adult↗

PubMed1987

The relationship of lactoferrin to the anemia of renal cell carcinoma.

This study was designed to examine whether lactoferrin, a glycoprotein contained in neutrophils which binds free iron, mediates the anemia associated with renal cell carcinoma. Preoperative hematocrit, urinalysis, serum iron, total iron binding capacity, and ferritin levels were obtained in 24 patients with hypernephroma. At the time of radical nephrectomy, a tumor specimen was obtained from all 24 patients and corresponding normal renal tissue was obtained from eight patients. Fifteen patients had low serum iron, whereas nine patients had normal serum iron. All tissue samples were snap frozen at the time of surgery and were subsequently sectioned into 3-microns slices using the cryostat. Then all the sectioned specimens were stained with FITC (fluorescein isothiocyanate) and peroxidase conjugated rabbit derived anti-human lactoferrin. Ten of the 15 patients with low serum iron had positive anti-lactoferrin staining in both the FITC and peroxidase systems. None of the tumors from patients with normal serum iron and none of the normal renal parenchyma exhibited positive anti-lactoferrin uptake. Stains for iron in the bone marrow of two patients with low serum iron showed increased iron stores. These studies suggest that lactoferrin mediates the anemia often seen in association with renal cell carcinoma.

Anemia↗

PubMed1989

High-resolution localization of lactoferrin in human neutrophils: labeling of secondary granules and cell heterogeneity.

We studied by electron microscopy the topography of the iron-binding protein lactoferrin in human peripheral blood neutrophils by immunogold labeling of thin-sectioned cells. We show that fixation in 0.3% glutaraldehyde, supplemented by 2% formaldehyde, and combined with embedding in the hydrophilic resin LR White results in excellent preservation of the lactoferrin antigenicity and of the neutrophil microanatomy. Most of the immunogold marking was seen on the specific (secondary) granules of polymorphonuclear leukocytes, thus strengthening prevailing views on the subcellular distribution of lactoferrin in neutrophils. We document that a minority (8-10%) of neutrophils showed significant amounts of lactoferrin associated with a flocculent, protein-like material seen inside large cytoplasmic vacuoles. We show that circulating neutrophils comprise 6-10% of cells that are virtually devoid of lactoferrin labeling. This finding provides specific cytochemical support for the concept that human polymorphonuclear leukocytes are made up of a heterogeneous population of cells.

Adult↗

PubMed1995

Lipopolysaccharide-inactivating activity of neutrophils is due to lactoferrin.

Neutrophils can inactivate lipopolysaccharide (LPS), thereby blocking the ability of LPS to prime fresh neutrophils for enhanced fMLP-triggered release of superoxide. Here we show that inactivation of LPS by neutrophils was primarily due to lactoferrin. A time course for inactivating LPS showed that neutrophils (5 million/ml) took 30 min to inactivate 10 ng/ml LPS. Mononuclear cells could not inactivate LPS under the same conditions. Experiments with radioactive LPS showed that inactivated LPS remained in the medium and was not taken up or destroyed by the neutrophils during inactivation. Inactivated LPS still gelled Limulus lysate and primed monocytes. Cell-free medium from neutrophil suspensions also inactivated LPS. A single LPS-inactivating factor was purified from medium by heparin-agarose chromatography. SDS-PAGE showed a single band at 80 kDa, which was identified as lactoferrin by immunoblotting. Antilactoferrin immunoglobulin G removed the LPS-inactivating activity from purified lactoferrin and cell-free medium. Surprisingly, even purified neutrophil lactoferrin required 30 min to inactivate LPS, indicating inherently slow binding of lactoferrin to LPS.

Culture Media↗

PubMed1999

Three-dimensional structure of mare diferric lactoferrin at 2.6 A resolution.

Lactoferrin is a monomeric glycoprotein with a molecular mass of approximately 80 kDa. The three-dimensional structure of mare diferric lactoferrin (mlf) has been determined at 2.6 A resolution. The protein crystallizes in the space group P 212121with a=85.2 A, b=99.5 A, c=103.1 A with a solvent content of 55 % (v/v). The structure was solved by the molecular replacement method using human diferric lactoferrin as the model. The structure has been refined using XPLOR to a final R -factor of 0.194 for all data in the 15-2.6 A resolution range. The amino acid sequence of mlf was determined using a cDNA method. The final refined model comprises 5281 protein atoms, 2 Fe3+, 2 CO32-and 112 water molecules. The overall folding of mlf is similar to that of other proteins of the transferrin family. The protein folds into two globular lobes, N and C. The lobes are further divided into two domains, N1 and N2, and C1 and C2. The iron-binding cleft is situated between the domains in each lobe. The N lobe appears to be well ordered and is more stable than the C lobe in mlf unlike in other lactoferrins, where the C lobe is the more stable. The opening of the binding cleft in the N lobe of mlf is narrower than those in other proteins of the transferrin family. This is very unusual and is found only in mare lactoferrin. Apart from certain hydrophobic interactions at the mouth of the cleft, one salt-bridge (Lys301 . . . . . . . . Glu216) crosses between the two walls of the cleft. The two lobes are connected covalently by a three-turn alpha-helix involving residues 334-344. The N lobe displays a highly ordered structure with appreciably low temperature factors. The iron coordination is more symmetrical in the N lobe than in the C lobe. There are only 16 intermolecular hydrogen bonds in the structure of mlf.

Amino Acid Sequence↗