SEARCH · Search PubMed

Results for “Lactoferrin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources

PubMed2001

A milk protein lactoferrin enhances human T cell leukemia virus type I and suppresses HIV-1 infection.

Human T cell leukemia virus type I (HTLV-I) and HIV-1, causative agents of adult T cell leukemia/lymphoma and AIDS, respectively, are transmitted vertically via breast milk. Here we demonstrate that lactoferrin, a milk protein that has a variety of antimicrobial and immunomodulatory activities, facilitates replication of HTLV-I in lymphocytes derived from asymptomatic HTLV-I carriers and transmission to cord blood lymphocytes in vitro. Transient expression assays revealed that lactoferrin can transactivate HTLV-I long terminal repeat promoter. In contrast, lactoferrin inhibits HIV-1 replication, at least in part, at the level of viral fusion/entry. These results suggest that lactoferrin may have different effects on vertical transmission of the two milk-borne retroviruses.

Adjuvants, Immunologic↗

PubMed1999

Myeloid transcription factor C/EBPepsilon is involved in the positive regulation of lactoferrin gene expression in neutrophils.

Targeted mutation of the myeloid transcription factor C/EBPepsilon in mice results in gram-negative septic death at 3 to 5 months of age. This study defines the underlying molecular defects in their terminal granulocytic differentiation. The mRNA for the precursor protein of the cathelin-related antimicrobial peptides was almost completely absent in the bone marrow cells of C/EBPepsilon-/- mice. This finding may help explain their susceptibility to gram-negative sepsis, because both are bacteriocidal peptides with potent activity against gram-negative bacteria. Superoxide production was found to be reduced in both granulocytes and monocytes of C/EBPepsilon-/- mice. While gp91 phox protein levels were normal, p47phox protein levels were considerably reduced in C/EBPepsilon -/- granulocytes/monocytes, possibly limiting the assembly of the NADPH oxidase. In addition, expression of mRNA of the secondary and tertiary granule proteins, lactoferrin and gelatinase, were not detected, and levels of neutrophil collagenase mRNA were reduced in bone marrow cells of the knock-out mice. The murine lactoferrin promoter has a putative C/EBP site close to the transcription start site. C/EBPepsilon bound to this site in electromobility shift assay studies and mutation of this site abrogated binding to it. A mutation in the C/EBP site reduced the activity of the promoter by 35%. Furthermore, overexpression of C/EBPepsilon in U937 cells increased the activity of the wild-type lactoferrin promoter by 3-fold. In summary, our data implicate C/EBPepsilon as a critical factor of host antimicrobial defense and suggests that it has a direct role as a positive regulator of expression of lactoferrin in vivo.

Animals↗

PubMedDate not supplied

Tear lactoferrin levels in chronic meibomitis associated with acne rosacea.

PURPOSE: To determine tear lactoferrin levels in patients with chronic diffuse meibomitis associated with acne rosacea and to investigate their role in the development and perpetuation of some inflammatory ocular surface complications. METHODS: In this non-randomized, controlled trial performed in a tertiary care center, eight patients with biopsy-proven acne rosacea and blepharitis, and ten patients with seborrheic blepharitis not associated with acne rosacea formed the study groups and ten normal patients were used as controls. Schirmer I test results, tear break-up time and radial immunodiffusion (Lactoplate) tests on tear samples of the three groups were compared. RESULTS: Compared to controls, tear lactoferrin concentrations were lower in both the acne rosacea and seborrheic blepharitis groups. However, this decrease was significant in only the seborrheic blepharitis group (p = 0.026). One patient in the acne rosacea group, with the lowest measurement, developed bacterial keratitis. CONCLUSIONS: Though within the normal range, tear lactoferrin levels in patients with acne rosacea and seborrheic blepharitis were lower than controls. Low concentrations of lactoferrin may play a role in the ocular surface inflammatory components associated with these diseases.

Adolescent↗

PubMed1975

Lactoferrin in the duodenal juice of patients with chronic calcifying pancreatitis.

We have shown the presence of lactoferrin in the pancreatic juice of patients with chronic calcifying pancreatitis (CCP) and its absence in controls. In this work, lactoferrin has been found in saliva, but neither in gastric juice nor in bile. Therefore, a technique for collecting the human duodenal juice with a rubber tube and preventing its contamination with saliva is described. In the duodenal juice of 15 patients with CCP, 52 controls without evident pancreatic diseases, and 9 cases of pancreatic diseases other than CCP, lactoferrin has been searched for by immunological methods before and after an intravenous injection of CCK-PZ (3 U CHR) + secretin ( C U). The lactoferrin test in positive in 5, inconclusive in 6, and negative in 41 cases, and in the 9 cases of non-CCP pancreatic diseases it is negative. The use of this test in the diagnosis of CCP is proposed.

Adolescent↗

PubMed2001

Three-dimensional structure of a new form of mare lactoferrin in 70% PEG 400 at 3.8 A resolution.

Three-dimensional (3D) structure of a new form of diferric mare lactoferrin has been determined at 3.8 A resolution. The protein was crystallized in a space group P2(1)2(1)2(1) with a = 80.1 A, b = 103.7 A, c = 112.2 A with a solvent content of 57%. The structure was solved by molecular replacement method using the model of native mare lactoferrin. The structure has been refined using X-PLOR to a final R-factor of 22.6% for all the data in 15.0-3.8 A resolution range. The final refined model comprises 5281 protein atoms, 2Fe3+ and 2CO3(2-) ions. The protein folds into two globular N- and C-lobes. The two lobes are further divided into two domains N1, N2 in the N-lobe and C1, C2 in the C-lobe. The overall folding of the protein is similar to that observed for the native protein. The superposition of Calpha traces of native mare lactoferrin and the present structure gives an r.m.s shift of 0.7 A. There is a slight variation in the orientation of two lobes but the domain orientations in the present structure are identical to those observed in the native mare lactoferrin.

Animals↗

PubMed2002

Lactoferrin: mechanism of action, clinical significance and therapeutic relevance.

Lactoferrin is an iron binding protein involved in a large spectrum of biological actions including antimicrobial actions. Lactoferrin plays a central role in ferrokinetics: it binds free iron with great affinity limiting the amount of ions available for microorganism's metabolism. Its role in the host defence mechanisms consists in bacteriostatic and bactericidal effects; moreover it inhibits the proliferation of other microbes such as fungi and viruses. Lactoferrin is also involved in the modulation of immune system and recent studies indicate that lactoferrin directly modulates both production and function of neutrophils and monocytes.

Lactoferrin↗

PubMed2003

[A case of corneal lactoferrin amyloidosis secondary to trichiasis].

PURPOSE: A case of corneal lactoferrin amyloidosis secondary to trichiasis is reported. CASE: A 30-year-old male suffered from trichiasis with an elevated gray whitish lesion just under the center of the cornea in his right eye. The lesion had an irregular surface. METHOD: We excised the corneal lesion, and studied the excised corneal lesion morphologically. RESULT: The deposit observed just under the corneal epithelial layer was positive for Congo red staining, and showed dichroism under polarizing microscopy. The deposit also showed a immunoreactivity against anti-human lactoferrin antibody. CONCLUSION: The morphological study proved that the deposits under the corneal lesion were derived from lactoferrin. Long term injury of the corneal surface by trichiasis may lead to the deposition and structural changes of lactoferrin originating from tears.

Adult↗

PubMedDate not supplied

[New method for the determination of anti-lactoferrin activity of microorganisms].

A new method for the determination of the antilactoferrin activity (ALfA) of microorganisms, based on the detection of lactoferrin by the enzyme immunoassay, is proposed. The new method widens the spectrum of microorganisms to be tested, makes it possible to detect lactoferrin inactivation by bacteria producing antagonistically active substances (muramidases, organic acids, hydrogen peroxide, etc.), increases the reliability of the determination of the ALfA antilactoferrin activity of microorganisms due to the increased accuracy of its quantitative characterization. Testing of the culture fluid for lactoferrin following the growth of microorganisms in a medium with this protein revealed the capacity to inactivate lactoferrin in bacteria (Escherichia coli, Salmonella sp.) and yeast-like fungi (Candida sp.), isolated from feces and clinical material, of persons with carrier states, dysbiotic disturbances and pyoinflammatory diseases.

Candida↗

PubMed1991

Polymorphism and altered methylation of the lactoferrin gene in normal leukocytes, leukemic cells, and breast cancer.

Human lactoferrin has been found to be decreased or absent in most breast cancer and leukemia cells. In order to examine the lactoferrin gene for both structural alterations and the degree of methylation, we isolated a 2117-kilobase complementary DNA from human breast tissue. This complementary DNA was used to probe DNA extracted from normal peripheral blood, leukemia cells from patients, leukemia cell lines, and breast cancer cell lines. Immunocytochemical staining of these cells confirmed the decreased production of lactoferrin in malignancy. MspI restriction enzyme fragment patterns demonstrated genetic polymorphism which occurred in DNA from both normal and malignant cells. Polymorphism was also noted with XbaI. In this case, there were two fragment patterns that were only found in DNA from malignant cells. The degree of DNA methylation was also evaluated. The methylation pattern of DNA extracted from malignant cells was highly variable and generally less methylated than DNA extracted from normal WBCs. It is possible that the decrease in lactoferrin associated with cancer is multifactorial and includes gene structural changes as well as altered regulation. Further study is needed to determine whether the changes found in this study are the result of the malignancy or contribute to its onset or maintenance.

Amino Acid Sequence↗

PubMed1990

[Lactoferrin and leukocytes in the blood of oncologic patients].

Peripheral blood lactoferrin level and leukocyte count were measured by enzyme immunoassay in the sera of 288 normal subjects and 247 patients with malignant tumors of various localization. Normal lactoferrin level has been found 1055 +/- 191.0 ng/ml. In the patients it was changed either higher or lower, irrespective of the tumor site. This has led the authors to a conclusion on the acute phase pattern of the time course of lactoferrin level in oncologic patients. Elevation of lactoferrin level anticipated changes in leukocyte count.

Female↗

PubMed1992

Plasma elastase alpha 1-antitrypsin and lactoferrin in sepsis: evidence for neutrophils as mediators in fatal sepsis.

Increased vasopermeability and vasodilation, presumably the result of endothelial perturbation, are considered among the basic pathogenetic mechanisms in septic shock. Neutrophils have been implicated as a source for mediators in endothelial injury. We measured elastase-alpha 1-antitrypsin (alpha 1AT) complexes and lactoferrin as markers for release of neutrophil granule contents in plasma from patients with sepsis on admission to the Intensive Care Unit, and we delineated the relationship of neutrophil activation to other inflammatory parameters and to hemodynamic and biochemical parameters. Levels of elastase-alpha 1AT and lactoferrin significantly correlated with each other (r = 0.58; p less than 0.008), and were increased (greater than 3.33 and 5 nmol/L, respectively) in 96% and 71% of the patients, respectively. Lactoferrin, but not elastase-alpha 1AT, correlated with the number of white blood cells (r = 0.38; p = 0.008). Elastase-alpha 1 AT levels were significantly higher (p = 0.008), whereas white blood cell counts were lower (p = 0.015) in patients with shock when compared with patients without abnormal blood pressure. Both elastase-alpha 1AT and lactoferrin levels correlated with lactate levels (r = 0.33; p = 0.024 and r = 0.30; p = 0.04), suggesting a role for neutrophil activation in the pathogenesis of hypoxygenation. In addition, elastase-alpha 1AT correlated with the concentrations of interleukin 6 (IL-6) (r = 0.46; p = 0.001) and C3a (r = 0.38; p = 0.009), suggesting that cytokines and complement may contribute to the degranulation of neutrophils in sepsis. Elastase-alpha 1AT complexes were inversely related to C1-inhibitor (r = -0.33; p = 0.028) and to platelet numbers (r = -0.42; p = 0.003). Levels of elastase-alpha 1AT complexes in plasma appeared to be of prognostic significance; levels were higher in 27 patients who died than in 21 patients who survived (p = 0.01). The mortality in 27 patients with concentrations below 10 nM was 37%, whereas it was 81% in 21 patients with higher levels. The overall mortality in this study was 56%. These results provide further evidence that activation and degranulation of neutrophils, induced by multiple agonists, are involved in the development of fatal complications in patients with sepsis.

Bacterial Infections↗

PubMed1991

[Lactoferrin].

Lactoferrin is a protein present in many fluids of the human organism and in the secondary granules of polymorphonuclear cells (PMN). In the blood stream lactoferrin favours the segregation of PMN by mediating and amplifying the immune response, and realizes a negative feedback control on the Colony Forming Unit Granulocyte/Macrophage (CFU-GM) proliferation. At intestinal level it promotes iron absorption and prevents bacterial overgrowth. The antibacterial effect of lactoferrin is used clinically to prevent bacterial infections in neutropenic patients submitted to chemotherapy for leukemic diseases type M1, M2, M4 and M5, according to FAB criteria. In patients affected by chronic pancreatitis the lactoferrin concentration, in duodenal juice, is found to be significantly higher than in normal subjects. This finding suggests a pathogenetic role of the protein in chronic pancreatitis.

Bacteria↗

PubMed1991

Purification of transferrins and lactoferrin using DEAE affi-gel blue.

1. A simple method for purifying transferrins and lactoferrin is described. 2. The method consists of a preliminary step of dye-ligand chromatography using DEAE Affi-Gel Blue as the gel matrix at pH 7.5. In this chromatographic step, the transferrins and lactoferrin were readily separated from the bulk of the other proteins by start buffer elution. 3. Differences in the chromatographic behaviour of the various serum transferrins (monkey, human, rabbit, pig, chicken and duck) and ovotransferrin upon DEAE Affi-Gel Blue chromatography can be attributed to differences in the anionic charge of the transferrins in 0.02 M potassium phosphate buffer, pH 7.5, thus resulting in the differential retardation of these protein molecules by the gel matrix. 4. The result of DEAE Affi-Gel Blue chromatography of human lactoferrin is different from that for the transferrins. This may possibly reflect the differences in the strength of interaction between lactoferrin and transferrin with this gel matrix.

Amino Acid Sequence↗

PubMed1989

[Tear lactoferrin content in normal Chinese adults and various ocular diseases].

The authors found the tear lactoferrin content in normal Chinese adults to be 1.46 +/- 0.32 mg/ml (mean +/- 1 SD), and the mean counting rate of its unsaturated binding power of iron 63,660 +/- 17,010/min/ml (mean +/- 1 SD), with very significant positive correlation between the two, irrespective of sex or eye distinction. Tear lactoferrin began to decrease after 40 years of age, and remarkably so after 70. The authors deemed the measurement of tear lactoferrin a reliable and sensitive marker for the diagnosis of keratoconjunctivitis sicca. In patients with bacterial corneal ulcer and acute catarrhal conjunctivitis, the lactoferrin content in tears was normal, in chronic catarrhal conjunctivitis, the unsaturated binding power of iron was decreased.

Adult↗

PubMed1989

Immunocytochemical detection of lactoferrin in human gastric carcinomas and adenomas.

In gastric carcinomas, including 20 cases of intestinal type and 10 cases of diffuse type, in adenomas with mild to severe dysplasia (20 cases), and in hyperplastic polyps (10 cases), the presence of lactoferrin was investigated by immunohistochemistry. Incomplete or complete intestinal metaplasia or both and normal gastric mucosa were also tested. Preoperative hematocrit and serum iron levels (18 patients) were recorded. An evident reactivity for lactoferrin was encountered in intestinal type carcinomas, adenomas, and incomplete intestinal metaplasia, whereas diffuse-type carcinomas, hyperplastic polyps, and complete intestinal metaplasia were always unstained; mucous neck cells of the antrum and body were also positive for lactoferrin. The results are discussed in relation to the increased requirement of iron by neoplastic cells, although in gastric carcinomas serum iron levels appear to be unrelated to the immunohistochemical presence of lactoferrin.

Adenoma↗

PubMed1987

[Stimulation of expression of IgM and IgG receptors on human thymus lymphocytes after treatment with lactoferrin in vitro].

It was established by immunofluorescence that lactoferrin, one of the heteroorganic thymus antigens, can stimulate the expression of Fc mu and Fcj receptors on thymus lymphocytes. The stimulating effect of lactoferrin on T mu cells is more pronounced with the level of these cells in the thymus being low. Its effect on Tj cells seems independent of their level in the thymus and may be related to their precursor differentiation. It can be assumed that one of the functions of lactoferrin in the thymus is to influence the process of differentiation of T mu and Tj cells and to regulate their level in the thymus. Lactoferrin, like other heteroorganic thymus antigens, may take part in the functional maturation of different subpopulations of thymocytes, including T mu and Tj thymus cells.

Adolescent↗

PubMed1988

[Lactoferrin: biochemistry, physiological roles, and value in human biology].

Lactoferrin and transferrin exhibit very similar structure and biochemical properties but they behave as two distinct antigens and their affinity for ferric ions is not of the same magnitude. The biological functions of lactoferrin are not all well understood. It has strong bacteriostatic properties, it plays a role as a regulator of human granulopoiesis and it is probably involved in the hyposideremia of acute inflammation. Measurement of lactoferrin was first applied in pancreatic juice or duodenal fluid as a diagnostic tool for pancreatic diseases. More recently plasma lactoferrin has been used as an index of total circulating neutrophil pool in hematological disorders and in uremic patients during hemodialysis. Its clinical usefulness is still discussed for the early diagnostic of infectious diseases.

Anti-Infective Agents↗

PubMed1988

Augmented release of human leucocyte lactoferrin (and elastase) during coagulation.

Lactoferrin, an iron binding protein, present in specific granules of neutrophils has been shown to be released concomitantly with elastase, when neutrophils are activated in vitro. Using enzyme-linked immunosorbent assay, lactoferrin release has been studied during blood coagulation, a more physiological system for studying the in vivo neutrophil activation in vitro. The assay has a lower detection limit of 1.0 ng/ml with intra and interassay coefficients of variation of 8 and 14% respectively. Median plasma and serum lactoferrin levels were 144 and 705 ng/ml respectively. The difference was statistically significant at p less than 0.0001. The median elastase proteinase inhibitor complex (EPIC) levels in plasma and serum were 85 and 176.5 ng/ml respectively. This difference was also highly significant at p less than 0.0001. There was no correlation between these parameters in the plasma samples. However, there was a statistically significant correlation between these measurements in sera at p less than 0.001 (Kendall's rank correlation). Release of lactoferrin and elastase-A1PIC during coagulation reflects the activation of neutrophils in vivo, especially during inflammation.

Adult↗