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PubMed2001

Haptoglobins as markers of blood-CSF barrier dysfunction: the findings in normal CSF.

Cerebrospinal fluid from 39 healthy individuals showed evidence for increasing blood-CSF barrier permeability with age, and confirmed that haptoglobins are more sensitive but less predictive markers of barrier permeability than total protein. Haptoglobin (Hp) species were identified by polyacrylamide gel electrophoresis followed by immunoblotting. Hp 1-1 (35 A, 85 kDa) was detected in all (9/9) subjects who exhibited this phenotype. Hp 2-1 (42 A, 120 kDa) was detected in 53% (8/15) of subjects in whom Hp 2-1 was the phenotype. Hp 2-2 (54 A, 160 kDa) was detected in only 20% (3/15) of subjects who exhibited this phenotype. The likelihood of detecting any haptoglobin species corresponded to the molecular size and the consequent resistance offered by the barrier. Among younger subjects aged < or =45 years, a significant difference in incidence occurred between the two smaller species Hp 1-1 and Hp 2-1. However, among those aged >45, the significant difference in incidence was between the two larger species Hp 2-1 and Hp 2-2. The incidence of detection among those with Hp 2-1 phenotypes was higher in the older age group. The increased likelihood of detecting haptoglobins with age is in keeping with the notion that barrier function is compromised by age, and also indicates that Hp 2-1 and Hp 2-2 are sensitive markers of barrier function. The appreciable incidence of haptoglobins in normal CSF, even of the larger species, suggests reservation in assuming that their presence signifies barrier damage.

Adolescent↗
PubMedDate not supplied

C-reactive protein and haptoglobin in the evaluation of a community-based malaria control programme.

When cross-sectional surveys are used to evaluate malaria intervention programmes in the community, the prevalence of morbidity is difficult to assess because of the fluctuating nature of malarial fever. We have therefore investigated the impact of bed net usage on 2 surrogate markers of malarial morbidity: (i) elevated C-reactive protein (CRP) (> 8 mg/L) plus detectable parasitaemia, as an indicator of malaria-induced acute-phase response; and (ii) reduced haptoglobin levels (< 180 mg/L), which in this population indicates malaria-induced intravascular haemolysis. Among 1505 Gambian children 1-5 years old, examined on a single occasion at the end of the malarial transmission season, 5% had parasitaemia plus fever, while 24% had parasitaemia plus elevated CRP, and 35% had low haptoglobin. The proportion of children who had parasitaemia plus elevated CRP was significantly lower among those who had slept under insecticide-treated bed nets than among those who did not use a bed net (16% vs. 34%, P < 0.003), and the proportion with low haptoglobin differed similarly (24% vs. 49%, P < 0.003). Use of an untreated bed net had a weaker effect on both indices (22% had parasitaemia plus elevated CRP, 34% had low haptoglobin). CRP and haptoglobin are simple and inexpensive to measure in large numbers of people, and these results suggest that they could be useful for the assessment of malaria intervention programmes.

Bedding and Linens↗
PubMed2002

Serum-haptoglobin concentration in Danish slaughter pigs of different health status.

A cross-sectional study was conducted with 617 finishing pigs aged 10-25 weeks in 11 commercial herds of different health statuses as defined by the Danish monitoring program for specific-pathogen-free (SPF) herds. A standard clinical examination was performed and a blood sample was obtained from each pig for determination of haptoglobin concentration in serum. Pigs aged 10-14, 15-19 and 20-25 weeks in conventional herds had higher haptoglobin concentrations than high-health SPF (SPF-x) pigs of the same age. There was no significant difference between SPF-x pigs of different ages. Conventional pigs aged 15-19 and 20-25 weeks had higher haptoglobin concentrations than conventional pigs aged 10-14 weeks. Herd influenced the haptoglobin concentration. Lame pigs and pigs with tail or ear bite had elevated haptoglobin concentrations. No significant effect of respiratory symptoms or umbilical hernia was found.

Animals↗
PubMed1998

Cloning and sequencing of cDNA encoding haptoglobin, an acute phase protein in Syrian hamster, Mesacricetus auratus.

One of the most prominent acute phase proteins in Syrian hamster (Mesacricetus auratus) was identified as haptoglobin and cDNA encoding this protein was sequenced. The deduced amino acid sequence of the mature protein is 83.6, 80.5, 79.6, and 76.1% identical to those of mouse, rat, human (1 s isoform), and dog homologues, respectively. As compared with six known members of this family, including human haptoglobin-related protein, hamster haptoglobin had 11 unique substitutions and one unique codon deletion, that is, the corresponding residues have been conserved in all other members. This indicates that hamster haptoglobin gene has accumulated these unique mutations after the time of cricetid-murid split while the ancestral sequence has been conserved in all other species examined. Hamster haptoglobin, however, contains nine cysteine residues, all of which are found in conserved positions in primate and rodent homologues. Molecular phylogenetic trees of alpha- and beta-chains show that the alpha-chain is more divergent than the beta-chain and that the difference in genetic distance between canine and hamster alpha-chains is much greater than that of corresponding beta-chains.

Amino Acid Sequence↗
PubMed2003

Interleukin 6, serum amyloid A and haptoglobin as markers of treatment efficacy in pigs experimentally infected with Actinobacillus pleuropneumoniae.

The possibility to use acute phase proteins to monitor the elimination of a bacterial infection in pigs would facilitate an objective assessment of treatment with various antimicrobial substances. To examine this possibility, the acute phase response (IL-6, serum amyloid A (SAA), and haptoglobin) elicited by Actinobacillus pleuropneumoniae and its reduction on treatment with various antibiotics was studied in serum from specific pathogen free (SPF) pigs. Pigs were infected intranasally with A. pleuropneumoniae serotype 2, and either left as non-treated control pigs or treated with different antibiotics intramuscularly at onset of respiratory disease (20h post-infection). Pigs responded to the infection with prominent increases in activity and concentrations of IL-6, SAA, and haptoglobin. These responses were to a certain extent overlapping and covered the time span from a few hours after infection until development of detectable levels of specific antibodies (7-10 days post-infection in untreated pigs). The haptoglobin response lasted until the end of the study on day 17 and thereby partly coincided with the antibody response. Treatment with antimicrobials that effectively reduced establishment of the infection with A. pleuropneumoniae also reduced the duration of all three acute phase responses, and reduced the concentration of serum haptoglobin. In contrast, less efficacious treatments did not reduce these acute phase responses. Thus, acute phase reactants can be applied to monitor therapeutic effects of antimicrobial drugs in the pig and measurements of IL-6, SAA and haptoglobin could add valuable information about the stage of infection during a disease outbreak.

Actinobacillus Infections↗
PubMed1999

Haptoglobin transport into human ovarian follicles and its binding to apolipoprotein A-1.

Controlled ovarian stimulation was induced in 19 women for in vitro fertilisation/embryo transfer. After ovum pick-up, haptoglobin titres were determined by ELISA in sera and homologous follicular fluids. The haptoglobin phenotype of each subject was assessed and the penetration of the protein forms through the blood-follicle barrier was predicted on the basis of their molecular weight. The penetration threshold compatible with the barrier integrity was calculated as 92%, 73% and 57% of the blood level of phenotypes Hpt 1-1, Hpt 1-2 and Hpt 2-2 respectively. Penetration values comparable/lower or higher than threshold were found associated with 46 of 49 and 3 of 49 fertilised oocytes, respectively. Complexes of haptoglobin with apolipoprotein A-1 were isolated from follicular fluids by affinity chromatography with haemoglobin. The haptoglobin beta chain, after Western blotting and incubation with apolipoprotein A-1, was found to be involved in the protein-protein interaction as detected by anti-apolipoprotein A-1 antibodies. Complexes from separate fluids were analysed by electrophoresis and densitometry: the plain beta chain/apolipoprotein A-1 stoichiometric ratio was 0.75 and 1.40 in fluids associated with fertilised and unfertilised oocytes respectively. The results suggest that haptoglobin transport in the follicle depends on the integrity of the blood-follicle barrier and might be associated with oocyte quality, possibly by interfering with the role of apoliprotein A-1 in cholesterol or vitamin E exchange between high-density lipoproteins and granulosa cells.

Apolipoprotein A-I↗
PubMed2003

Identification of a novel iron regulated staphylococcal surface protein with haptoglobin-haemoglobin binding activity.

Staphylococcus aureus is an extremely adaptable pathogen causing a wide variety of infections. Staphylococcal surface proteins that directly interact with host extracellular proteins greatly contribute to virulence and are involved in adhesion, immune escape and nutrient acquisition. In our extensive search for highly immunogenic, in vivo-expressed, staphylococcal proteins, previously, we identified a novel member of the family of Gram-positive anchor motif proteins with a predicted 895 amino acid long sequence. In order to determine the ligand for this novel LPXTG cell wall protein, we employed affinity purification of human plasma using the recombinant form of the protein. Two-dimensional electrophoresis of eluted plasma proteins identified haptoglobin as a specific binding partner. Importantly, we also observed this specific ligand binding when living S. aureus cells were exposed to biotin-labelled haptoglobin (Hp) in a FACS-based assay. Targeted deletion of the gene eliminated Hp-binding, a function that has not been attributed to S. aureus before. Based on these data we specified the protein as the staphylococcal haptoglobin receptor A (HarA). Similarly to other haptoglobin receptors identified in Gram-negative pathogens, HarA binds not only Hp, but also haptoglobin-haemoglobin complexes with an even higher affinity, as demonstrated in in vitro binding assays. Employing specific deletion mutants, ligand binding was localized to two homologous regions with about 145 amino acid residues located within the N-terminal part of the protein. In addition, we demonstrated that expression of HarA was strictly controlled by iron through the iron-dependent transcriptional regulator Fur. Based on these data we propose that HarA can be added to the list of staphylococcal virulence factors with a most likely function related to iron acquisition.

Amino Acid Sequence↗
PubMed2002

Haptoglobin interacts with the human mast cell line HMC-1 and inhibits its spontaneous proliferation.

Haptoglobin (Hp) is an acute phase reactant produced by hepatocytes. There is evidence for an immunomodulatory potential of Hp, though there is no clear evidence yet about the mechanisms of this action. We have previously shown that Hp interacts with the beta2-integrin CD11b/CD18. In addition, other investigators reported the binding of Hp to B lymphocytes through the CD22 receptor, and to neutrophils through two different receptors. In the present study, we investigated the interaction of haptoglobin with the human mast cell line HMC-1. We report that fluorescein isothiocyanate (FITC)-labelled haptoglobin binds to this cell line and that binding is increased by calcium in a dose- and time-dependent manner. Hp binding sites on HMC-1 were upregulated upon stimulation with phorbol myristate acetate (PMA)/A23187 and after treatment with anti-CD43 and anti-CD44 monoclonal antibodies (MoAbs). HMC-1 cells do not express either CD11b/CD18 or CD22 receptors, indicating that the haptoglobin-binding receptor on this cell line is different from the known receptors. Assessment of cell function showed that Hp inhibits the spontaneous growth of HMC-1 up till 40% at higher Hp concentrations, but it did not exhibit any effect on the expression of CD54 on the release of either tryptase or IL-1ra. In conclusion, haptoglobin binds specifically to human mast cells via a receptor different from CD11b/CD18 and CD22, and may play a role in the modulation of mast cell functions. Exploration of Hp effects in mast cell-dependent diseases such as allergic rhinitis and urticaria seems warranted.

Antigens, CD↗
PubMed1983

Haptoglobin concentrations in children aged 9-10 years and its correlation to indirect parameters of erythrocyte turnover.

Low serum haptoglobin values are often found in children. Nine different parameters were studied in 125 healthy children aged 9-10 years to get indirect information on erythrocyte turnover and its possible relation to the low mean plasma haptoglobin level in childhood. The mean LD activity was higher than in adults. The mean carboxyhaemoglobin per cent saturation (COHb %) and the mean serum haptoglobin concentrations were lower than in adults. No significant correlation was found between serum haptoglobin and serum iron, serum bilirubin and COHb %. Significant correlation at low r-values was found between serum iron, serum bilirubin and COHb %. The low serum haptoglobin levels often seen in children seemed not to be caused by an increase in erythrocyte turnover.

Adolescent↗
PubMed1992

Development of concanavalin A-enzyme immunosorbent assay for glycated haptoglobin using polyclonal and monoclonal antibodies.

Two-site lectin-haptoglobin-enzyme immunosorbent assay (L-Hp-ELISA), is described. Haptoglobin binding to Concanavalin A, immobilized to polystyrene microtiter plate, was estimated by anti-haptoglobin polyclonal and monoclonal antibodies conjugated with horse-radish peroxidase. The range of haptoglobin binding to Concanavalin A, measured by the L-Hp-ELISA was 25 to 300 ng/ml using polyclonal, and 50 to 600 ng/ml using monoclonal anti-haptoglobin antibodies, respectively.

Acetylation↗
PubMed2005

Haptoglobin dampens endotoxin-induced inflammatory effects both in vitro and in vivo.

We report that haptoglobin, an acute-phase protein produced by liver cells in response to interleukin-6 (IL-6), can modulate the inflammatory response induced by endotoxins. We provide evidence that haptoglobin has the ability to selectively antagonize lipopolysaccharide (LPS) effects in vitro by suppressing monocyte production of tumour necrosis factor-alpha, IL-10 and IL-12, while it fails to inhibit the production of IL-6, IL-8 and IL-1 receptor antagonist. In two animal models of LPS-induced bronchopulmonary hyperreactivity and endotoxic shock, haptoglobin knockout mice were more sensitive to LPS effects compared to their wild-type counterparts. The present data suggest that haptoglobin regulates monocyte activation following LPS stimulation. The increase in haptoglobin levels during an acute-phase reaction may generate a feedback effect which dampens the severity of cytokine release and protects against endotoxin-induced effects.

Acute-Phase Reaction↗
PubMed1998

Changes in serum haptoglobin level after allergen challenge test in asthmatic children.

Bronchial asthma is characterized by airway inflammation, which underlies the phenomenon of bronchial hyperresponsiveness. Previous studies have shown that this correlates with the serum concentration of haptoglobin. The occurrence of the late asthmatic response (LAR) after an allergen challenge test is associated with airway inflammation. The objectives of this study were to examine serum levels of haptoglobin during the 24 h after allergen challenge and to compare changes between the subjects with and without LAR. We studied two groups of children with perennial asthma who developed the early asthmatic response (EAR) only (group I: n = 14), and EAR but also LAR (group II: n = 14) after an allergen (Dermatophagoides pteronyssinus) challenge test. Serum concentrations of haptoglobin were measured at baseline, at EAR, and at 2 h (recovery), 8 h (LAR), and 24 h after the challenge. Baseline levels were similar in the two groups (group I: 128 +/- 57 mg/dl; group II: 129 +/- 50 mg/dl). In group I, there was no significant change in the level at any time point; in contrast, the subjects in group II showed a relative fall (92 +/- 40 mg/dl) at 8 h, and an increase (161 +/- 79 mg/dl) at 24 h after the challenge. Our results indicate that the serum concentration of haptoglobin decreases at the time of LAR and is subsequently replenished during the ensuing time. Although further studies are needed, we think that haptoglobin may be inflused into the airways during the inflammatory process associated with LAR, and that this may be followed by "overshooting" production.

Allergens↗
PubMed1998

Nephelometric determination of haptoglobin plasma concentrations in fattening pigs.

The haptoglobin plasma concentrations in 110 fattening pigs living on three commercial farms and in 28 animals on the university pilot farm were measured using a nephelometric detection method based on an immunoassay. Following calibration of the automated analyser (Nephelometer BN 100) with a human haptoglobin standard, the measurements were performed using anti-human antiserum from rabbits. Differences in age, gender or breed of apparently healthy animals seem to have no influence on the plasma concentration of the protein. The average plasma level of haptoglobin in animals suffering from acute respiratory diseases was significantly higher. Furthermore, an increase was observed in animals without clinical symptoms living on a farm characterized by obvious defects in housing conditions. Comparison studies of the nephelometric method by use of a human or porcine standard for calibration and different anti-human or anti-porcine antisera with radial immunodiffusion as a reference method resulted in high correlation coefficients for all variations. Optimal accuracy was obtained by calibrating the analyser with a porcine standard. Haptoglobin determinations have been shown to be a useful tool for health monitoring during the integrated pig-production process, allowing recognition of performance-reducing conditions. The immunonephelometric determination method is suitable for quantifying porcine plasma haptoglobin for routine checks. The use of animal-specific standards for calibration improves the accuracy of this method.

Animals↗
PubMed2006

Relationship between haptoglobin, serum amyloid A, and clinical status in a survey of dairy herds during a 6-month period.

BACKGROUND: Haptoglobin and serum amyloid A are major acute phase proteins in cattle. Dairy cattle often develop pathologic conditions in the peripartum period; acute phase proteins may be useful in their diagnosis. OBJECTIVES: The purpose of this study was to compare the accuracy of serum haptoglobin (Hp) and serum amyloid A (SAA) concentrations with clinical health status for diagnosing disease during the peripartum period in dairy cattle. METHODS: Dairy cows from 4 herds were evaluated every 15 days over a 6-month period. Health status was determined by thorough clinical examination. Haptoglobin and SAA concentrations were measured in serum using validated methods and the results were classified as positive or negative based on defined cutoff points. Disease prevalence, sensitivity, and specificity were compared using clinical examination as the gold standard. RESULTS: A total of 1896 samples from 158 cows were analyzed. Significant increases in mean Hp and SAA concentrations were observed in the week following parturition in both primiparous and multiparous cows, although high interindividual variability was observed. Both Hp and SAA had low sensitivity but higher specificity in determining disease status compared with clinical examination. Increased concentrations of Hp and SAA were found in <10% of samples from clinically healthy cows, except in the week after parturition. CONCLUSIONS: Haptoglobin and serum amyloid A should be used with caution as markers of inflammation in the week after calving. Poor sensitivity in other postpartum periods could be related to the higher incidence of chronic (vs acute) inflammation. Haptoglobin may be appropriate for routine screening, but further work needs to be done to assess its value as an indicator of herd health.

Animals↗
PubMed1967

Haptoglobin levels in serum of various strains of mice.

Only a single type of haptoglobin was found in the serum of 11 strains of mice, but there were wide variations between strains with respect to the amount of haptoglobin found. In the AKR and C3H strains, in which haptoglobin was low or absent, various agents stimulated production of high levels of haptoglobin. Serum haptoglobin rose in association with the development of leukemia in AKR mice, but remained low when C3H mice developed mammary tumors.

Animals↗
PubMed1998

hgpB, a gene encoding a second Haemophilus influenzae hemoglobin- and hemoglobin-haptoglobin-binding protein.

Haemophilus influenzae requires heme for growth and can utilize both hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified a hemoglobin- and hemoglobin-haptoglobin-binding protein, HgpA, in H. influenzae HI689. Mutation of hgpA did not affect binding or utilization of either heme source. The hgpA mutant exhibited loss of a 120-kDa protein and increased expression of a 115-kDa protein. These data suggested that at least one other gene product is involved in binding of these heme sources by H. influenzae. A 3.2-kbp PCR product derived from HI689 was cloned. The nucleotide sequence indicated a separate, distinct gene with high homology to hgpA, which would encode a 115-kDa protein. Primers were designed for directional cloning of the structural gene in the correct reading frame. Sonicates of induced Escherichia coli harboring the cloned open reading frame bound both hemoglobin and hemoglobin-haptoglobin. An insertion/deletion mutant of H. influenzae at the newly identified locus, designated hgpB, was constructed. The 115-kDa protein was not detected in the mutant after affinity purification using biotinylated hemoglobin. An hgpA hgpB double-mutant strain exhibited a reduced ability to utilize hemoglobin-haptoglobin, although it was unaltered in the ability to utilize hemoglobin. Affinity isolation of hemoglobin-binding proteins from the double mutant resulted in isolation of an approximately 120-kDa protein. Internal peptide sequencing revealed this protein to be a third distinct protein, highly homologous to HgpA and HgpB. In summary a second hemoglobin- and hemoglobin-haptoglobin-binding protein of H. influenzae has been identified and characterized, and the presence of an additional protein of similar function has been revealed.

Amino Acid Sequence↗
PubMed1994

Haptoglobin as an indicator of infection in sheep.

An automated method for the estimation of the acute phase protein haptoglobin was developed and used to compare the blood haptoglobin concentrations of 42 sheep examined post mortem with other haematological findings in infectious and non-infectious conditions. Haptoglobin was also assayed in 863 sheep from nine apparently normal flocks; of these sheep seven per cent had significantly raised haptoglobin levels. The studies showed that haptoglobin was useful as a marker for the presence of bacterial infection in sheep, and was more sensitive, specific and efficient and less likely to give false positive and negative results than a haematological examination.

Animals↗
PubMed1980

Kinetic study of the interaction between rat haptoglobin and rat liver cathepsin B.

One of the roles of the acute phase reactants (APR), according to Koj, is to regulate the action of tissue proteinases released during the inflammatory reaction. To study this phenomenon in vitro, rat liver cathepsin B (EC 3.4.22.1), a lysosomal proteinase, and a typical APR, rat serum haptoglobin, were purified. By kinetic study, haptoglobin was found to inhibit cathepsin B and the inhibitory activity of a competitive type was increased with the molecular weight of the substrate. When 125I-labelled denatured bovine serum albumin (BSA) was used as a substrate, the apparent Michaelis constant (Km app.) for cathepsin B was 5 +/- 0.4 X 10(-6) M. When haptoglobin was added, the apparent inhibition constant (Ki app.) was 3.5 +/- 1.5 X 10(-8) M. Native haptoglobin was not catabolized by cathepsin B while under the same conditions denatured haptoglobin was degraded by the enzyme.

Animals↗