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PubMed1997

Study of haptoglobin-hemoglobin complexes by titration curves, capillary electrophoresis and capillary isoelectric focusing.

A novel method is described for monitoring complex formation between macromolecules, based on combined isoelectric focusing-electrophoresis in capillaries. The example studied is the binding of serum haptoglobin (Hp) to hemoglobin (Hb). A known amount of Hb is focused in a capillary in a pH 6-8 range (pI of Hb = 7.0) and thus kept temporarily "immobilized" in the electrophoretic chamber. Subsequently, increasing amounts of ligand (Hp) are loaded cathodically and allowed to sweep past the focused Hb zone. As the complex formed has a pI value well-outside the bounds of such a pH gradient (the 1:1 molar Hb-Hp complex has a pI of 5.5, the 1 to 1/2 molar Hp-Hb complex has a pI of 5.0) it escapes immobilization and moves past the detector window, where it is monitored and quantified. Since the detector is set at 416 nm, where only Hb absorbs, and since the molar extinction coefficient of Hb is well known, it is quite easy to calculate the molar amount of Hb bound to the complex. As an additional check, the amount of unreacted Hb can now be mobilized by disrupting the pH gradient and allowing this residual free Hb to also reach the detector and be quantified. The method is easy, fast, simple and fully automated and thus could represent a valid alternative to existing methods in clinical chemistry for quantifying the amount of Hp in human sera in pathological conditions, such as hemolytic anemias and transfusion reactions.

Ampholyte Mixtures↗
PubMed1999

Quantitation of human haptoglobin: comparative ELISA studies using adsorption and capture methods.

Three ELISA methods for the quantitation of haptoglobin (Hp) in plasma and albumin are described: a polystyrene direct adsorption method and capture methods with antibody and hemoglobin. Hp aggregates generated by 60 degrees C heating showed as much as a hundred-fold higher response by polystyrene adsorption compared to the two capture methods, while unheated Hp showed comparable responses by the three methods.

Adsorption↗
PubMedDate not supplied

Evaluation of a competitive immunoassay for the detection of bovine haptoglobin.

A competitive immunoassay to quantify the serum concentration of bovine haptoglobin (hp) using time resolved fluorescence was compared with an indirect method of hp assay (haemoglobin binding assay), using sera taken from healthy animals (n = 158), animals experimentally infected with Haemophilus somnus (n = 10) and from sick animals requiring veterinary treatment (n = 440). Upper limits of normality (for normal animals) were tentatively established for the immunoassay (2.1 micrograms ml-1) and for the haemoglobin binding assay (103 micrograms ml-1). The competitive immunoassay detected elevated hp in 62.5 per cent of field sera by comparison with only 19.2 per cent using the conventional haemoglobin binding assay. Serum albumin concentration did not correlate with hp although concentrations of globulins and copper did correlate. However, these parameters (serum globulin and copper) were found to be insensitive markers of inflammatory disease.

Acute-Phase Reaction↗
PubMedDate not supplied

Haptoglobin 1-1 is associated with susceptibility to severe Plasmodium falciparum malaria.

The haptoglobin (Hp) phenotypes were determined by polyacrylamide-gel electrophoresis in plasma samples obtained in 1997 from 113 Plasmodium falciparum malaria patients (aged 1-12 years) with strictly defined cerebral malaria, severe malarial anaemia, or uncomplicated malaria and 42 age-matched healthy controls from the same area (coastal Ghana). Hp1-1 was significantly more prevalent among the patients (43%) than among healthy controls (7.1%), whereas Hp2-1 and Hp2-2 were underrepresented among the patients (11% and 2%, respectively) compared to the control donors (33% and 14%, respectively). No significant difference in frequency of Hp0 was observed between patients and controls. Among the malaria patients, the Hp1-1 phenotype was significantly more prevalent among patients with the complications of cerebral malaria and severe anaemia compared to patients with uncomplicated disease, whereas the reverse was seen with respect to Hp2-1 and Hp2-2. Our data suggest that the Hp1-1 phenotype is associated with susceptibility to P. falciparum malaria in general, and to the development of severe disease in particular.

Child↗
PubMed2001

Haptoglobin polymorphism and schizophrenia: genetic variation on chromosome 16.

Recently, it was shown that schizophrenia is accompanied by an activation of the inflammatory response system with signs of an acute phase response, such as increased plasma haptoglobin (Hp) concentrations. Hp is characterized by a molecular variation with three known phenotypes, i.e. Hp 1-1, Hp 2-1 and Hp 2-2. The aim of the present study was to examine Hp phenotypic and genotypic frequencies in schizophrenic patients. Hp phenotyping was carried out in 98 Northwestern Italian schizophrenic patients and the phenotypic and genotypic distributions were compared with the distributions established in the Northwestern Italian population. Plasma Hp concentrations were determined by means of a laser nephelometric method. The allele frequency of the Hp phenotypes in schizophrenia, i.e. Hp 1-1 (9.2%), Hp 2-1 (38.8%) and Hp 2-2 (52.0%), was significantly different from that in the Northwestern Italian population, i.e. Hp 1-1 (17.0%), Hp 2-1 (51.3%) and Hp 2-2 (38.5%). The frequency of the Hp-2 gene was significantly higher in schizophrenic patients (71.7%) as compared with the observed frequency in the Northwestern Italian population (62.5%). The alterations in Hp phenotypic and genotypic distribution were more pronounced in the schizo-affective, disorganized, undifferentiated and residual schizophrenic patients than in paranoid schizophrenic patients. More than a third (35.7%) of the schizophrenic patients showed plasma Hp concentrations which were higher than the upper limits of normality. Schizophrenia is accompanied by an altered distribution of the Hp phenotypes and genotypes, suggesting that genetic variation on chromosome 16 may be associated with schizophrenia.

Adult↗
PubMed2003

Development of an enzyme immuno assay for the determination of porcine haptoglobin in various body fluids: testing the significance of meat juice measurements for quality monitoring programs.

Quantification of haptoglobin (Hp), an acute phase protein, in blood is presently discussed as being useful to monitor animal health. We developed an enzyme immuno assay (EIA) which is specific for porcine Hp, is not impaired by hemolytic samples and is sufficiently sensitive to be applied in meat juice. Hp was purified from porcine serum by affinity chromatography on hemoglobin Sepharose followed by gel filtration. A specific rabbit antiserum was obtained. In a competitive approach, biotinylated porcine Hp was used as tracer and incubated with Hp standard or sample in microtiter plates. The limit of detection was 0.02 mg/l, parallelism of sample dilutions was proven; recovery of Hp added to serum samples was 96.4 +/- 4.7%. The coefficients of intra and inter-assay variation were 3.3 (n=5) and 10.2% (n=16), respectively. Hp was reliably quantified in blood serum and plasma, whole blood, saliva and meat juice. For healthy pigs of different ages (4 weeks and 6 months), mean Hp concentrations of about 0.5-0.7 mg/ml were observed. To test the significance of Hp measurements in other matrices, samples were obtained from fattening pigs or from slaughter pigs. Blood serum or plasma was collected in parallel. In whole blood, Hp concentrations were about 40% lower than in plasma, but were closely related (n=24,r=0.85,P<0.001). Saliva Hp concentrations ranged between 0.3 and 3.0 microg/ml and were marginally related with blood plasma concentrations (n=93,r=0.35,P<0.001). From 106 hybrid slaughter pigs (100-110 kg) blood and muscle samples (diaphragmatic pillar, d.p.; m. brachiocephalicus, m.b.) were collected. Meat juice was obtained after freezing and thawing. Concentrations were 0.39+/-0.5 mg/ml in serum and 0.04+/-0.06 mg/ml in meat juice. Hp concentrations in blood were closely correlated with those in d.p. juice (P<0.001,r=0.750) and m.b. juice (P<0.001,r=0.776). In view of the many reports on Hp measurements being predictive for animal health even in the subclinical range, we conclude that Hp quantification in meat juice might be useful to assess meat quality at slaughter and further along the processing chain in terms of animal health.

Animals↗
PubMed1999

Changes in concentrations of serum amyloid A protein, alpha 1-acid glycoprotein, haptoglobin, and C-reactive protein in feline sera due to induced inflammation and surgery.

To identify candidates for feline acute phase proteins, the concentrations of serum amyloid A protein (SAA), alpha 1-acid glycoprotein (alpha 1-AG), C-reactive protein (CRP), and haptoglobin (Hp) were measured in sera isolated from clinically normal and hospitalized (or diseased) cats, from cats with experimentally induced inflammation, and cats subjected to surgery for urinary diversion. Measurements were made by sandwich enzyme-linked immunosorbent assay and single radial immunodiffusion. The concentrations of SAA, alpha 1-AG, and Hp in sera from hospitalized cats were 7-11 times higher than in clinically normal cats. Similar results were obtained for the concentrations of SAA, alpha 1-AG, and Hp in cats with induced inflammation and cats subjected to surgery. By contrast, the serum concentration of feline CRP did not change significantly between clinically normal cats and hospitalized cats or inflammation-induced or post-surgery cats. Feline SAA concentration was found to increase earliest, with alpha 1-AG and Hp beginning to increase thereafter. From these results, feline SAA is concluded to be an acute phase reactant at the early stage of inflammation.

Animals↗
PubMed1999

Elevated serum haptoglobin in pigs infected with porcine reproductive and respiratory syndrome virus.

We examined the two acute phase proteins, alpha (alpha)-1 acid glycoprotein (AGP) and haptoglobin (HP), in serum of pigs following experimental porcine reproductive and respiratory syndrome (PRRS) virus infection. Increased levels of serum HP, but not AGP, were observed from 7 to 21 days post-inoculation in the infected pigs. Furthermore, serum IL-6 increased in the infected pigs, but TNF-alpha did not. The increase of serum IL-6 in pigs following PRRS virus infection may induce production of HP. Also, in the field investigation, serum HP in pigs was dramatically increased after exposure to the PRRS virus.

Acute-Phase Proteins↗
PubMed2001

Haptoglobin phenotype 2-2 overrepresentation in Cys282Tyr hemochromatotic patients.

BACKGROUND/AIMS: Patients with genotypic Cys282Tyr homozygous hemochromatosis differ largely in phenotypic presentation. The HFE mutation on itself does not explain the different manifestations of hemochromatosis. We hypothesized that the genetic haptoglobin (Hp) polymorphism, because of its effect on iron metabolism, could be a modifying factor that influences the clinical presentation of hereditary hemochromatosis. METHODS: In 167 Cys282Tyr homozygous hemochromatotic patients, the frequencies of Hp types (1-1, 2-1 and 2-2) and alleles (Hp1, Hp2) were compared with those in 918 healthy subjects. Clinical and laboratory indices of iron overload were incorporated in the analysis. RESULTS: The Hp 2-2 type was overrepresented in the patient group (P<0.01). Male patients carrying Hp 2-2 had higher serum iron (P=0.003) and ferritin levels (P=0.03) than those with a Hp 1-1 or 2-1 type. The amount of iron removed with phlebotomy was also higher in Hp 2-2 patients (P=0.03). CONCLUSIONS: The Hp 2-2 type is overrepresented among Cys282Tyr homozygous hemochromatotic patients. At diagnosis, iron overload was more pronounced in male patients carrying Hp 2-2. Our data suggest that Hp polymorphism affects iron metabolism in hereditary hemochromatosis.

Adult↗
PubMed1986

Systemic surgical shunts and splenomegaly as causes of haemolysis in portal hypertension in mansonic schistosomiasis. Evaluation through serum levels of haptoglobin, hemopexin and bilirubins.

The haemolytic process in hepatosplenic schistosomiasis is often regarded as a result of splenomegaly that can be increased by spontaneous or surgical shunts. The importance of splenomegaly and/or shunt on the etiology of haemolysis was studied in a group of 74 patients with hepatosplenic schistosomiasis and portal hypertension. They were divided into 4 groups: Group I (22 cases) - pre-operative; Group II (15 cases) - classic splenorenal shunt; Group III (22 cases) - selective portal decompression and Group IV (15 cases) - azygoportal disconnection with splenectomy. The first group is characterized by the presence of splenomegaly and the absence of shunt; the second by the presence of shunt and absence of splenomegaly; the third, by the presence of both splenomegaly and shunt and the last by absence of both, shunt and splenomegaly. In all cases, the levels of sensitive markers of haemolysis, such as haptoglobin and hemopexin as well as non-conjugated and total bilirubins were determined. Biochemical and coagulation parameters, used to evaluate the hepatic function, were also studied. The data was initially analysed according to a factorial experiment of 2 and standard least squares techniques were used to evaluate the effects of splenomegaly, shunt and their interaction. The results showed that the shunts always provoked haemolysis, even in the absence of splenomegaly, but the presence of both, splenomegaly and shunt, always increased the process of haemolysis.

Adolescent↗
PubMed1986

Binding of human haptoglobin to streptococci of serological group A.

All 11 streptococcal cultures of serological group A possessing antigen T4 bound human 125I-labelled haptoglobin (hp) and fibronectin (fbn). Most of these cultures also interacted with alpha 2-macroglobulin (alpha 2m), immunoglobulin G (IgG) and fibrinogen (fib), none with albumin. The binding of the labelled hp could be completely inhibited by unlabelled hp. It was not significantly affected by the other plasma proteins, except alpha 2m. Trypsinization of the streptococci reduced their binding activities for hp, fbn, fib and alpha 2m, but not for IgG. Extraction with guanidine hydrochloride removed non-covalently bound substances from the streptococci without loss in binding-activity for hp.

Antigens, Bacterial↗
PubMed1988

Further characterization of haptoglobin binding to streptococci of serological group A.

Certain group A streptococci with surface antigen T 4 possess surface receptors for human haptoglobin (Hp). Binding of 125I Hp 2-1 to two representative group A streptococcal cultures could be inhibited by unlabelled Hp 2-1, Hp 2-2 and Hp 1-1 but not by the alpha 1, alpha 2 or beta chains of Hp. Hp complexes formed with equine hemoglobin and asialo-Hp also reduced 125I-Hp 2-1 binding to group A streptococci. Hp binding proteins could be solubilized from streptococcal surface by hot acid treatment of the bacteria and purified by subsequent affinity chromatography on human Hp 2-1 sepharose. The isolated Hp binding proteins specifically inhibited 125I-Hp 2-1 binding to group A streptococci and retained their 125I-Hp 2-1 binding activity in a dot binding assay on nitrocellulose membranes. SDS-PAGE and protein blots of Hp binding proteins developed with 125I-labeled Hp 2-1 revealed numerous high molecular weight proteins with 125I-Hp 2-1 binding activity.

Bacterial Proteins↗
PubMed2001

Haptoglobin gene expression in human glioblastoma cell lines.

Increases in cerebrospinal fluid (CSF) levels of the acute phase protein haptoglobin (Hp) occur in central nervous system (CNS) disorders such as Alzheimer's disease. To establish if Hp CSF level increases can be associated with Hp expression in brain, reverse transcription-polymerase chain reaction (RT-PCR) experiments were conducted to determine if the Hp mRNA transcript is expressed in human glioblastoma cells. Furthermore, Western blots and immunoprecipitations were performed to elucidate if Hp protein is synthesized and secreted by human glioblastoma cells. The Hp mRNA (alpha2beta) transcript (1155 bp) was detected both in U-87MG and U-138MG cells, and was positively verified by nested PCR in which a part of the beta sequence (482 bp) was targeted for amplification. Despite the presence of Hp mRNA, Hp protein was not secreted by U-87MG cells as compared to the hepatoma cell line, HepG2, where Hp protein (approximately 46 kDa) was detected in the media. The results suggest the expression of Hp protein by glioblastoma cells is possible since the Hp mRNA transcript exist, but whether or not Hp mRNA is contained in a storage pool requiring a specific signal for translation or is transiently expressed remains to be uncovered in future studies.

Alzheimer Disease↗
PubMed1998

The porcine acute phase response to infection with Actinobacillus pleuropneumoniae. Haptoglobin, C-reactive protein, major acute phase protein and serum amyloid A protein are sensitive indicators of infection.

In an experimental infection model mimicking acute Actinobacillus pleuropneumoniae (Ap) infection in swine (Sus scrofa) by aerosol inoculation, the development of a number of typical clinical signs was accompanied by a prototypic acute phase reaction encompassing fever and an acute phase protein response peaking at around 2 days after infection. Haptoglobin, C-reactive protein (CRP), and major acute phase protein (MAP) responded with large increases in serum levels, preceding the development of specific antibodies by 4-5 days. Serum amyloid A protein (SAA) was also strongly induced. The increase, kinetics of induction and normalization were different between these proteins. It is concluded that experimental Ap-infection by the aerosol route induces a typical acute phase reaction in the pig, and that pig Hp, CRP, MAP, and SAA are major acute phase reactants. These findings indicate the possibility of using one or more of these reactants for the nonspecific surveillance of pig health status.

Actinobacillus Infections↗
PubMed2002

Regulation of haptoglobin secretion by recombinant bovine cytokines in primary cultured bovine hepatocytes.

We examined the regulation of haptoglobin (Hp) secretion in primary cultured bovine hepatocytes using recombinant bovine (rb) proinflammatory cytokines. The concentrations of Hp in the supernatant of cultured hepatocytes after incubation with rb interleukin (IL)-6, rb tumor necrosis factor (TNF)-alpha, rbIL-1 beta or rbIFN-gamma alone or with combinations of two of these cytokines were measured by ELISA. The rbIL-6, rbTNF-alpha and rbIL-1 beta increased Hp synthesis, but rbIFN-gamma did not, and rbIL-6 was the most effective Hp inducer among these cytokines. The Hp secretion was accelerated synergistically by combined treatment with rbIL-6 and rbTNF-alpha, whereas it remained unchanged with a combination of rbIL-6 and rbIL-1 beta. In contrast, the combination of rbIL-6 and rbIFN-gamma downregulated Hp secretion. In conclusion, IL-6 is the principal cytokine in Hp secretion in bovine hepatocytes in vitro, and its activity may be regulated by other cytokines.

Albumins↗
PubMed2000

Haptoglobin is a natural regulator of Langerhans cell function in the skin.

Langerhans cells (LC), the best-understood antigen presenting cells (APC) of the skin, are functionally plastic. Freshly obtained LC readily activate allogeneic T cells, but are incapable of activating autologous, naive T cells. When placed in culture in the presence of GM-CSF, LC up-regulate surface expression of class I and II MHC molecules along with co-stimulatory molecules, such as B7, CD40 and IL-12. This functional transformation enables the cells to activate naive, autologous T cells in vitro. It is paradoxical that intracutaneous administration of exogenous GM-CSF fails to induce intraepidermal LC to undergo functional transformation in situ. It has been reported that serum contains a factor that prevents fresh LC from undergoing functional transformation in culture, and the relevant serum factor has now been identified as haptoglobin (Hp), based on the following experimental results: (a) SDS-PAGE, amino acid sequencing, and mass spectrometric analyses of the inhibitory factor purified by high performance liquid chromatography (HPLC) from normal human serum revealed molecules completely homologous to Hp alpha-1 chain; (b) pure human Hp, but not serum depleted of Hp, inhibited fresh LC from acquiring the capacity to activate autologous T cells in vitro; (c) abundant Hp was detected in cytoplasmic compartments of fresh, but not cultured, LC. It was concluded that Hp, an acute phase protein, is a systemically-derived factor that prevents epidermal LC from spontaneously undergoing functional maturation in the skin. This novel property of Hp may be important in ameliorating or preventing certain T cell-dependent inflammatory skin diseases.

Animals↗
PubMed1990

Characterization of haptoglobin-binding properties of streptococci of serological group G.

Two group G streptococcal cultures (G 10187, G 11122) with surface antigen T4 possess surface receptors for human haptoglobin (Hp). G 10187 additionally interacted with immunoglobulin G and albumin, G 11122 with fibrinogen and fibronectin. Binding of 125I-Hp 2-1 was time-dependent, saturable, reversible in the presence of unlabelled Hp and could be inhibited by unlabelled human-Hp 2-1, -Hp 2-2, -Hp 1-1, Hp-hemoglobin complexes and by Hp preparations from pigs, horses and rabbits. The Hp binding sites could be destroyed by heat treatment (95 degrees C) and by proteolytic treatment of the bacteria. Hp binding sites were solubilized from group G streptococcal surface by heat treatment of the bacteria at acid pH and subsequently isolated by affinity chromatography on Hp 2-1 sepharose. SDS-PAGE and Western blotting of the Hp binding proteins revealed numerous protein bands with 125I-Hp 2-1 binding activity. Specific antibodies against G streptococcal binding proteins prepared in chickens inhibited binding of 125I-Hp to group G and group A streptococci, but not to Actinomyces pyogenes.

Albumins↗
PubMed1997

Diagnostic value of ferritin, haptoglobin, alpha 1-antitrypsin, lactate dehydrogenase and complement factors C3 and C4 in pleural effusion differentiation.

Searching to define diagnostic criteria for malignant and non-malignant pleural effusions, the differential diagnostic value of ferritin (FRT), haptoglobin (Hp), alpha 1-antitrypsin (alpha 1-AT), lactate dehydrogenase (LDH) and complement factors C3 and C4 were investigated prospectively in 100 consecutive patients with pleural effusions of various aetiologies. Pleural effusion FRT, C3 and C4 concentrations were found to be useful in differentiating exudates from transudates, so that transudates practically could be excluded in pleural effusion: serum FRT ratio lower than 0.5 and/or in pleural effusion values for C3 and C4 higher than 300 mg dl-1 and 70 mg dl-1, respectively. A pleural effusion: serum C3 ratio greater than 2 is seen only in malignant effusions. No discriminative pleural: serum ratio could be found in FRT and C4 values capable of differentiating malignant from non-malignant effusions. Pleural effusion alpha 1-AT and LDH values were elevated in exudates, as compared with transudates, and had an excellent sensitivity and predictive value, but low specificity, in differentiating malignant from non-malignant effusions. Finally, the sensitivity, specificity and positive predictive value of pleural effusion Hp concentrations were lower than those of FRT and complement factors C3 and C4, respectively.

Adult↗