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PubMed1985

Products of trypsin digestion of haptoglobin beta (heavy) chain.

Trypsin digestion of haptoglobin beta (heavy) chain resulted in five glycopeptides. The glycopeptides were characterized by carbohydrate and sulphydryl groups content; their molecular mass was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the presence or absence of 2-mercaptoethanol. None glycopeptide possessed hemoglobin-binding capacity. glycopeptide I did not form any precipitate with antihaptoglobin serum but was shown to inhibit strongly the reaction of haptoglobin or beta chain with the antiserum. Glycopeptide II showed dominant antigenic determinants in relation to native haptoglobin and to beta chain. Reaction of this glycopeptide with concanavalin A was almost twice higher than the corresponding reaction of haptoglobin. Glycopeptides IV and V were inactive in the reaction with the lectin. Glycopeptide III exhibited relatively the strongest cross-reactivity with the specific antihaptoglobin serum while its inhibitory activity in the immunoreaction was the lowest.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

A rapid and simple method for the preparation of a monospecific antibody to ovine haptoglobin.

Antisera specific to ovine haptoglobin were obtained by the immunization of rabbits with their own insolubilized haemoglobin after it had been allowed to react with a pool of haptoglobin-rich ovine serum. This method exploits the unique property of haptoglobin to bind with great specificity and affinity to both homologous and heterologous haemoglobin. The procedure is rapid, simple, inexpensive and could be readily applied to the production of antisera against the haptoglobins of other species.

Adsorption↗
PubMed1984

Structure and assembly of haptoglobin polymers by electron microscopy.

Haptoglobin (Hp) consists of light (L) and heavy (H) chains, the latter of which combine with hemoglobin alpha beta dimers to form a highly stable complex. Human haptoglobin assembles as HL units that occur in two allelic forms; HL1 , which is monovalent, and HL2 , which is divalent. As a result, three phenotypic forms exist in the human population: Hp1-1, the homozygous form in which the monovalent HL1 unit occurs as a dimer; Hp2-2, the homozygous form of the divalent HL2 unit, which gives a series of polymers; and the heterozygous Hp2-1 form, which gives a different series of polymers. We have investigated the structures and assembly properties of these two haptoglobin polymeric series in their complexes with hemoglobin using high-resolution scanning transmission electron microscopy. Polymers of complex are composed of ellipsoidal or bilobal head groups, which are the H alpha beta subunits connected by thin filament-like structures, which are the L chains. Polymers of size up to pentamers can be identified easily by counting the number of head groups in the molecule. Complex 2-1 and complex 2-2 trimers were studied extensively. The differences in detailed morphology show that while the 2-1 trimer is a linear polymer, the 2-2 trimer is a closed circular molecule. The micrograph images suggest that complex 2-2 tetramers and pentamers, and perhaps higher forms may also be cyclic. The structure of the L2 subunit of haptoglobin is shown to be composed of two domains, which may be similar in structure to the single domain of the monovalent L1 chain. The two L2 domains are connected by a hinge that has quite limited flexibility. Using these structural models, assembly characteristics and structural properties of the trimers and tetramers of complex 2-1 and complex 2-2 are described.

Biopolymers↗
PubMedDate not supplied

Measurement of serum haptoglobin as an indicator of the efficacy of malaria intervention trials.

Serum haptoglobin levels were measured by an enzyme-linked immunosorbent assay in Gambian children who participated in 3 malaria intervention trials with untreated or impregnated bed nets. In one study, in which a significant effect on clinical malaria was observed, the mean serum haptoglobin level was significantly higher in the intervention than in the control group. In the other 2 studies, in which no significant protection was observed, mean haptoglobin levels were similar in intervention and control groups. Measurement of serum haptoglobin may provide a useful indirect measure of the effectiveness of malaria control programmes.

Bedding and Linens↗
PubMed1986

Human haptoglobin binds to human myoglobin.

Human myoglobin, obtained from human heart, was purified to homogeneity by salt precipitation, crystallization and ion-exchange chromatography. Trace contamination by haemoglobin, if any, was removed by repeated adsorption on an immunoadsorbent of anti-haemoglobin antibodies. The interaction between human haptoglobin and human myoglobin was investigated by a solid-phase radioimmunoassay. Myoglobin adsorbents bound 125I-labelled haptoglobin in a specific manner. Linear Scatchard plots of the data indicate that human myoglobin has only one binding site for haptoglobin in terms of the binding affinity (Ka = 8.5 X 10(6) M-1). These results suggest that haptoglobin not only binds haemoglobin but also binds human myoglobin, although with an affinity that is much lower than that of haemoglobin. The physiological significance of this interaction is discussed.

Adsorption↗
PubMed2006

HPLC analysis of discrete haptoglobin isoform N-linked oligosaccharides following 2D-PAGE isolation.

Glycosylation is a common but variable modification that regulates glycoprotein structure and function. We combined small format 2D-PAGE with HPLC to analyse discrete human haptoglobin isoform N-glycans. Seven major and several minor haptoglobin isoforms were detected by 2D-PAGE. N-Glycans released from Coomassie-stained gel spots using PNGase were labeled at their reducing termini with 2-aminobenzamide. HPLC analysis of selected major isoform N-glycans indicated that sialic acid composition determined their separation by isoelectric focussing. N-Glycans from two doublets of quantitatively minor isoforms were also analysed. Although separation of each pair of doublets was influenced by sialylation, individual spots within each doublet contained identical N-glycans. Thus, heterogeneity in minor haptoglobin isoforms was due to modifications distinct from N-glycan structure. These studies describe a simple method for analysing low abundance protein N-glycans and provide details of discrete haptoglobin isoform N-glycan structures which will be useful in proteomic analysis of human plasma samples.

Chromatography, High Pressure Liquid↗
PubMed2006

Patients with congenital hypothyroidism demonstrate different altered expression of plasma fibrinogen and haptoglobin polypeptide chains.

OBJECTIVES: To compare the plasma protein profiles of treated and untreated congenital hypothyroidism (CH) patients with those of normal control infants. DESIGN AND METHODS: Plasma samples were subjected to two-dimensional gel electrophoresis and silver staining or lectin detection. Resolved protein spots were analyzed by using computerized densitometry software. RESULTS: The significant enhanced expression of the fibrinogen gamma-chain and reduced expression of haptoglobin beta-chain were demonstrated in the profiles of untreated CH patients using both silver staining and lectin detection methods. Lectin detection resolved only a single cluster of the haptoglobin beta-chain for the untreated patients, in contrast to five isoform clusters detected in the controls' and treated CH patients' profiles. CONCLUSIONS: Plasma from untreated CH patients demonstrated different altered expression of fibrinogen and haptoglobin polypeptide chains, which was normalized when patients were treated. Our data also suggest differences in structures of the N-glycans of haptoglobin beta-chain of the untreated CH patients.

Child↗
PubMed2005

Haptoglobin expression by shed endometrial tissue fragments found in peritoneal fluid.

OBJECTIVE: To confirm the endometrial glandular epithelial and stromal cells in tissue fragments recovered from peritoneal fluid and to quantify haptoglobin expression. DESIGN: Prospective, randomized study. SETTING: University of Missouri-Columbia School of Medicine and Health Care System. SUBJECT(S): Women undergoing laparoscopic surgery for diagnosis or treatment of endometriosis or for laparoscopic tubal cautery for desired sterilization. INTERVENTION(S): Aspiration of peritoneal fluid at laparoscopic surgery. MAIN OUTCOME MEASURE(S): Histological confirmation of endometrial glandular epithelial and stromal cells and evaluation of haptoglobin gene expression and protein localization in shed endometrial tissue fragments recovered from peritoneal fluid. RESULT(S): More visible tissue fragments were found in the peritoneal fluid from women with endometriosis (n = 28/65) than from that of women without endometriosis (n = 5/34). Of these tissues, endometrial glands and stroma were histologically confirmed in about half of women with endometriosis (n = 13/28) and without endometriosis (n = 3/5). Retrogradely shed endometrial tissues recovered from peritoneal fluid robustly express haptoglobin. CONCLUSION(S): Haptoglobin expression by retrogradely shed endometrial tissues in peritoneal fluid supports a mechanism whereby these purported precursors of endometriotic lesions escape immune destruction. Low recovery of histologically confirmed endometrial tissue fragments from peritoneal fluid reveals the potential difficulties for using these tissues for studies modeling the pathogenesis of endometriosis.

Analysis of Variance↗
PubMed2006

Effect of porcine respiratory coronavirus infection on lipopolysaccharide recognition proteins and haptoglobin levels in the lungs.

Porcine respiratory coronavirus (PRCV) potentiates respiratory disease and proinflammatory cytokine production in the lungs upon intratracheal inoculation with lipopolysaccharide (LPS) at 1 day of infection. This study aimed to quantify LPS-binding protein (LBP), CD14 and haptoglobin in the lungs throughout a PRCV infection. LBP and CD14 recognize LPS and enhance its endotoxic activity, whereas haptoglobin dampens it. Gnotobiotic pigs were inoculated intratracheally with PRCV (n = 34) or saline (n = 5) and euthanized 1-15days post inoculation (DPI). Virus was detected in the lungs from 1 to 9DPI. Cell-associated CD14 in lung tissue increased up to 15 times throughout the infection, due to an increase in highly CD14+ monocyte-macrophages from 1 to 12DPI and CD14+ type 2 pneumocytes from 7 to 9DPI. LBP and soluble CD14 levels in bronchoalveolar lavage fluids were elevated from 1-12DPI, with up to 35- and 4-fold increases, respectively. Haptoglobin levels increased significantly (x4.5) at 7DPI. In addition, we found that PRCV could sensitize the lungs to LPS throughout the infection, but the response to LPS appeared less enhanced at the end of infection (7DPI). The marked increases in LBP, CD14 and haptoglobin were not correlated with the extent of the LPS response.

Acute-Phase Proteins↗
PubMed2002

Elevated levels of nitric oxide and low levels of haptoglobin are associated with severe malarial anaemia in African children.

Severe malarial anaemia (SA) is a major complication of malaria and an important cause of child mortality and morbidity. However, the pathogenesis behind SA is poorly understood. Nitric oxide (NO) is known to play a protective role against clinical malaria but is also suggested to have a pathogenic role in cerebral malaria (CM). Erythrophagocytosis by splenic macrophages has been implicated in the pathogenesis of SA. In this study, plasma levels of NO, neopterin, haptoglobin and C-reactive protein (CRP) were measured in paediatric patients with CM, n=77, SA (n=28) and uncomplicated malaria (UM n=53). Haptoglobin levels were significantly lower in SA (median (interquartile range) 25 (17-59) mg/l) than in both CM and UM (40 (24-80) mg/l and 110 (60-160) mg/l, respectively, P<0.001). In contrast, NO levels were higher in SA (38 (28-51) micromol/l) than in CM and UM (21 (15-32) micromol/l and 10.3 (5.6-17) micromol/l, respectively, P<0.001). A significant negative correlation between haptoglobin and NO was seen in the SA group. No such correlation was observed within the UM or CM groups. No significant differences in neopterin levels were observed between any of the three groups, neither was there any correlation between parasitaemias and neopterin levels. The low haptoglobin and high levels of NO in this SA group may contribute to haemolysis. Taken together our results support the hypothesis that immune-mediated erythrocyte destruction is involved in the pathogenesis of malarial anaemia.

Anemia↗
PubMedDate not supplied

Bovine haptoglobin as a possible immunomodulator in the sera of transported calves.

Bovine haptoglobin, which has been recognized as an acute phase protein following tissue injury and inflammation, was detected as a 33 k + 20 k Dalton fraction in the sera from calves transported by road for 2 days. The sera also possessed suppressive activity on lymphocyte proliferative response to concanavalin A. A significant correlation (r = 0.57, P < 0.05) was observed between haptoglobin concentrations and lymphocyte suppression in the sera. Furthermore, the haptoglobin fraction obtained from acute phase sera exerted dose-dependent suppression on lymphocyte blastogenesis. These circumstantial data suggest the possible involvement of bovine haptoglobin, at least in part, as an immunomodulator in serum suppression of lymphocyte blastogenesis in transported calves.

Adjuvants, Immunologic↗
PubMed2000

Fast determination of haptoglobin phenotype and calculation of hemoglobin binding capacity using high pressure gel permeation chromatography.

A new and fast method for haptoglobin (Hp) phenotyping was developed based on high pressure gel permeation chromatography of hemoglobin-supplemented serum. Haptoglobin phenotypes 1-1, 2-1, and 2-2 are resolved on the difference in size of their hemoglobin-haptoglobin complexes. Results are available in less than 15 min. Results of the chromatographic typing correspond to those obtained by conventional starch gel electrophoresis. Next to the phenotyping of haptoglobin, the method allows reproducible calculation of the hemoglobin binding capacity (HBC) of human serum. Using this methodology, reference values for HBC were found to be 0. 75+/-0.25 g/l, with the lowest HBC in Hp 2-2 subjects and the highest in Hp 1-1 subjects (P<0.05). In contrast to earlier findings, the ratio HBC:Hp concentration was found to be comparable for the three Hp types. In conclusion, this method allows a rapid phenotyping in critical clinical conditions where Hp phenotyping can be useful, e.g. determining the donor's phenotype in liver transplantation.

Adult↗
PubMed1987

Is the turbidimetric immunoassay of haptoglobin phenotype-dependent?

Comparison of the turbidimetric immunoassay of haptoglobin with a reference method (the RID technique with appropriate correction for phenotype) clearly showed the turbidimetric assay to be phenotype-dependent. Correction factors for the three main phenotypes were calculated and reference values determined. The observed overall reference range of haptoglobin, irrespective of the phenotype, was 0.56-3.76 g/L. After correction for phenotype, reference values for the three types were: Hp 1-1: 0.77-2.49; Hp 2-1: 0.86-4.76; and Hp 2-2: 0.48-3.15 g Hp/L. From our reference values for the several phenotypes of haptoglobin it may be argued that phenotyping is desirable only when the uncorrected haptoglobin value, determined by turbidimetry, is within the range 0.38-0.98 g/L. Limited to hemolytic diseases, phenotype determination can be omitted beyond this range.

Haptoglobins↗
PubMed1999

Associations between haptoglobin polymorphism, lipids, lipoproteins and inflammatory variables.

The haptoglobin allele frequencies and the phenotype distribution were determined in 741 male Caucasian workers, aged 35 to 59 years. The association of the haptoglobin polymorphism with various clinical and biochemical parameters was investigated. Furthermore a possible interaction with the apo E polymorphism on lipid and lipoprotein traits was analysed. The frequency of Hp1 and Hp2 was found to be 0.401 and 0.599, respectively. The observed distribution of Hp types (Hp 1-1, 15.5%; Hp 2-1, 49.3%; Hp 2-2, 35.2%) was in Hardy-Weinberg equilibrium. Age, body mass index, smoking, alcohol intake and blood pressure were comparable between the three Hp groups. Subjects with Hp 2-2 had significantly higher serum total and free cholesterol concentration compared to those in other haptoglobin types (P = 0.006 and P = 0.003). Similarly, apo B levels were significantly higher among Hp 2-2 individuals (P = 0.02). No significant differences were demonstrated between the Hp phenotypes in HDL cholesterol, apo A-I, apo E, Lp(a), cholesteryl esters, fibrinogen and C-reactive protein concentrations, although for the latter an increase was noticed in Hp 2-2. The effects of Hp type and apo E type on Lp(a) and on free cholesterol levels were found to be significantly multiplicative, with the highest free cholesterol values observed in subjects having Hp 2-2 and the apo epsilon4 allele. Significantly lower Lp(a) levels were observed in individuals carrying Hp 1-1 and an epsilon2 allele than in subjects without the epsilon2 allele. In conclusion, haptoglobin polymorphism may play an important role in the regulation of lipoprotein metabolism and could contribute to the risk of coronary heart disease. Larger samples are needed to clarify the clinical relevance of the gene-gene (Hp-apo E) interaction on lipids and lipoproteins.

Adult↗
PubMedDate not supplied

Association of the haptoglobin phenotype (1-1) with falciparum malaria in Sudan.

The haptoglobin phenotypes of Sudanese patients with complicated and uncomplicated falciparum malaria, and those of uninfected randomly selected individuals, were determined by electrophoresis of sera on polyacrylamide gels followed by benzidine staining of the gels. Among 273 malaria patients, the proportions with haptoglobin phenotypes (1-1), (2-1) and (2-2) were 60.8%, 29.7% and 9.5%, respectively, and in 72 cerebral malaria patients the proportions were 63.9%, 29.2%, and 6.9%. The distribution among 208 control individuals was 26.0%, 55.8% and 18.3%, respectively. The difference between patients and controls was highly significant (P < 0.001). The distribution of the different haptoglobin phenotypes among the randomly selected group of 208 Sudanese individuals was comparable to that in many other populations. The results suggests that the haptoglobin phenotype (1-1) is associated with susceptibility to falciparum malaria and the development of severe complications; alternatively, the other phenotypes may confer resistance.

Adult↗
PubMed1985

Massive intravascular hemolysis without serum haptoglobin depletion.

Hyperplasia of marrow histiocytes with extensive hemophagocytosis was found in a patient with cytomegalovirus infection. He experienced massive intravascular hemolysis, but, unexpectedly, no depression of the serum haptoglobin level was found by either single radial immunodiffusion or rate nephelometry. The unexpectedly high haptoglobin value may have been the result of "blockade" of the monocyte-macrophage system, with resultant failure to clear haptoglobin-hemoglobin complex rapidly from the circulation. Use of the techniques described for the indirect estimation of unbound serum haptoglobin alone should avoid confusing results in similar clinical circumstances.

Adult↗
PubMed2003

An intronic endogenous retrovirus-like sequence attenuates human haptoglobin-related gene expression in an orientation-dependent manner.

The human haptoglobin-related gene (HPR) gene codes for a haptoglobin-related protein (Hpr), a component of trypanosome lytic factor which circulates in plasma in small quantities. Except for the presence of a retrovirus-like element, RTVL-Ia, in intron 1, HPR is 92% identical in sequence to the closely linked human haptoglobin gene (HP) gene coding for haptoglobin. We have explored experimentally in tissue culture and in vivo in mice and in humans the influence of the retroviral-like sequence type Ia (RTVL-Ia) element on HPR expression. Transient expression in HepG2 cells of plasmids carrying the HPR promoter joined by a shortened version of intron 1 to the chloramphenicol acetyltransferase (CAT) vector showed that fragments containing the 5' long terminal repeat (LTR) had no significant effect. In contrast, a gag-pol related part and a pol-env-3'LTR related part of RTVL-Ia decreased expression to 20% and 40% of that in their absence but only when they were in naturally occurring orientation. The latter fragment that contains sequences reminiscent of elements essential for retrovirus viability, such as a splicing acceptor site, TATA box and polyA addition signal sequence, was further tested in site-specific transgenic mice. Similar to in vitro experiment, insertion of this fragment into an HPR transgene in mice reduced HPR expression to 50% compared to a transgene without the insert, but none of the viral sequence motifs appear to explain this effect. Instead, we found within the fragment two cryptic splicing donor sites whose products were present in transgenic mouse and in human liver RNA. Our data suggest that a combination of multiple small effects of RTVL-Ia including aberrant splicing accounts for the low (6%) expression of the present-day HPR relative to HP.

Alternative Splicing↗
PubMed2003

Haptoglobin and serum amyloid A in milk and serum during acute and chronic experimentally induced Staphylococcus aureus mastitis.

Local and systemic changes in the acute phase proteins, haptoglobin and serum amyloid A (SAA), were studied in six dairy cows during the acute and chronic phases of experimentally induced Staphylococcus aureus mastitis. Haptoglobin and SAA were measured in serum, and in milk from infected and healthy control udder quarters within each cow. Concentrations of haptoglobin and SAA increased rapidly in both serum and milk during the acute phase of mastitis and followed a similar pattern. Significantly raised milk concentrations of SAA were also found during chronic subclinical mastitis. Serum concentrations of SAA also tended to be higher during the chronic phase than pre-infection. Increases in milk haptoglobin and SAA were specific for the infected udder quarters. In conclusion, measurement of SAA in milk samples could be a useful tool in diagnosing mastitis.

Acute Disease↗