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Biomedical subjects

R van Ree

Publications and source records attributed to R van Ree.

At least 73 records · Page 4Linked to original sources
PubMed1995

Grass pollen immunotherapy induces highly cross-reactive IgG antibodies to group V allergen from different grass species.

Sera from two groups of patients receiving grass pollen immunotherapy were tested on IgG reactivity with group V allergen from six different grass species. One group of patients was treated with a mixture of 10 grass species, and the other with a mixture of five. Only Lolium perenne, Dactylis glomerata, and Phleum pratense were present in both mixtures. Although Anthoxanthum odoratum and Secale cereale were absent from the mixture of five, IgG responses to Ant o V and Sec c V were comparable in both patient groups. This reactivity was inhibited for 92-99% with L. perenne extract, illustrating the cross-reactive nature of the IgG antibodies. The presence of A. odoratum and S. cereale in the mixture resulted in only minor amounts of species-specific anti-group V IgG. These results indicate that application of just one grass species in immunotherapy might be sufficient to induce an IgG response that covers other relevant Gramineae species as well.

Allergens↗
PubMed1995

Vineyard snail allergy possibly induced by sensitization to house-dust mite (Dermatophagoides pteronyssinus).

A female patient experienced a severe allergic reaction after consumption of vineyard snails. The patient proved to be sensitized to house-dust mite (HDM) and demonstrated a positive skin test and specific IgE to snail (Eobania vermiculata, Lofarma). The snail RAST was > 80% inhibited by HDM, whereas the mite RAST was < 10% inhibited by snail extract. This is possibly another example of food allergy related to primary sensitization by an aeroallergen.

Adolescent↗
PubMed1995

Demonstration of carbohydrate-specific immunoglobulin G4 antibodies in sera of patients receiving grass pollen immunotherapy.

From a group of 92 patients receiving grass pollen immunotherapy, and selected on grounds of high IgG4 titers against Lol p I, sera were tested for IgG4 antibodies against the glycosylated grass pollen allergen Lol p XI. In 72 of 92 cases IgG4 antibodies were demonstrated. The N-glycan of Lol p XI was earlier shown to be an epitope for IgE antibodies. In the present study it was demonstrated that the carbohydrate structure is also recognized by IgG4 antibodies, illustrating that IgG4 responses are not immuno-restricted to peptide epitopes, as was suggested in several reports.

Allergens↗
PubMed1995

Rabbit IgG directed to a synthetic C-terminal peptide of the major grass pollen allergen Lol p I inhibits human basophil histamine release induced by natural Lol p I.

The potential role of allergen-specific IgG antibodies as 'blocking' antibodies in allergen-induced human basophil histamine release was investigated. This was studied in a model with the major grass pollen allergen Lol p I and polyclonal rabbit antisera directed against this allergen and against a synthetic peptide of its C terminus. When allergen and antibodies were allowed to preincubate, Lol p I induced histamine release was inhibited up to 85% by the antiserum against Lol p I. By omitting preincubation, and thereby more closely mimicking an in vivo situation, up to 55% inhibition was realized. This indicates that allergen-specific IgG can act as 'blocking' antibody without preincubation. Immunization of rabbits with a synthetic C-terminal peptide of Lol p I resulted in antibodies reactive with natural Lol p I. Despite their 100-fold lower avidity for Lol p I (as compared with antinatural Lol p I), these antibodies had the capacity to inhibit Lol p I induced histamine release for > 90% (up to 50% without preincubation). This indicates that it is possible to block histamine release induced by a major allergen with low-avidity IgG antibodies directed against a minor proportion of the allergen (25 amino acids). IgE antibodies from the donors studied were unreactive with this synthetic peptide, indicating that for blocking activity identical epitope specificity of IgE and IgG is not essential. This opens interesting perspectives for application of synthetic peptides in immunotherapy, distinct from their effects on T cell reactivity.

Allergens↗
PubMed1994

IgE-binding capacity of recombinant timothy grass (Phleum pratense) pollen allergens.

A panel of 60 cDNA clones coding for IgE-binding proteins from timothy grass pollen was immunocharacterized with sera from 30 patients allergic to grass pollen and antibodies raised against natural grass pollen allergens. In the cases of five representative patients in whom the IgE reactivity pattern with the recombinant allergens had been determined, IgE immunoadsorption experiments were performed. Recombinant Phl p I, Phl p V, and Phl p II and recombinant timothy grass profilin were used for immunoadsorption of the sera, and the percentage of remaining grass pollen-specific IgE was estimated. Although most of the patients showed IgE reactivity to a number of different natural and recombinant timothy grass pollen allergens, up to 66% of IgE directed against blotted total natural grass pollen allergens could be immunoadsorbed from the sera with recombinant Phl p V and Phl p I. The data point to the usefulness of recombinant allergens not only to determine IgE specificities of allergic patients but also to estimate the percentage of specific IgE that individuals produce against certain allergens. The fact that only a limited number of recombinant timothy grass pollen allergens account for a high percentage of grass pollen-specific IgE points to the possible usefulness of recombinant allergens not only for in vitro diagnosis but probably also for specific immunotherapy.

Allergens↗
PubMed1994

Complementary DNA cloning of the major allergen Phl p I from timothy grass (Phleum pratense); recombinant Phl p I inhibits IgE binding to group I allergens from eight different grass species.

BACKGROUND: Grass pollens, such as pollen from timothy grass (Phleum pratense), represent a major cause of type I allergy. OBJECTIVE: In this report we attempted to determine how cross-reactive allergenic components of grass pollens from different species can be represented by a minimum number of recombinant allergens. METHODS: We isolated and sequenced a timothy grass pollen cDNA coding for the major allergen Phl p I. A recombinant Phl p I-beta-galactosidase fusion protein, which bound to IgE in 87% of patients with grass pollen allergy, was produced in Escherichia coli. Using recombinant Phl p V and Phl p I, we defined representative patients' sera that bound to group I but not to group V allergens, as well as sera with reactivity against group I and group V allergens. IgE immunoblot inhibition studies were done with nitrocellulose-blotted pollen extracts from eight grass species with different geographic distribution. RESULTS: Preadsorption of patients' sera with recombinant nonfusion Phl p I strongly reduced IgE binding to group I allergens from the eight grasses, showing extensive cross-reactivity between species. CONCLUSION: A single recombinant group I allergen contains many of the IgE epitopes of group I isoallergens from a number of different grass species.

Allergens↗
PubMed1994

IgE and IgG cross-reactivity among Lol p I and Lol p II/III. Identification of the C-termini of Lol p I, II, and III as cross-reactive structures.

In this study, the homologous C-termini of Lol p I, Lol p II, and Lol p III were shown to contain cross-reactive B-cell epitopes. This was demonstrated by inhibition studies with purified Lol p I, II, and III and synthetic peptides of their C-termini. It was ruled out that the observed cross-reactivity was caused by cross-contamination of the purified allergens. Both human IgE and IgG bound to the C-terminus of Lol p I. These antibodies were cross-reactive with Lol p II and, more specifically, with its C-terminus. Within a small panel of allergic patients, no cross-reactivity with Lol p III was found. A hyperimmune polyclonal rabbit antiserum against Lol p I also recognized the Lol p I C-terminus. As for human antibodies, cross-reactivity with Lol p II and its C-terminus was demonstrated. Cross-reactivity with Lol p III was demonstrated with C-terminal peptides, but not with native Lol p III. A polyclonal rabbit antiserum against Lol p II bound to the C-terminal peptides of both Lol p II and III. This binding was inhibited with Lol p I, confirming that cross-reactive structures exist not only on the C-termini of Lol p II and Lol p I, but also of Lol p III and Lol p I. The existence of cross-reactivity between Lol p I and Lol p II and III possibly contributes to the frequently observed cosensitization for these allergens in grass-pollen-allergic patients.

Allergens↗
PubMed1994

Value of monoclonal antibody-based assays: advantages and drawbacks.

Monoclonal antibodies (mAbs) directed to allergens are highly specific tools in allergen standardization and quantification. Their mono-specificity allows sensitive detection of individual allergens. It is the same quality that asks for caution. MAbs can be too specific: isoforms of allergens can be missed. On the other hand, mono-specific antibodies can also be crossreactive, possibly resulting in overestimation of allergen content. Lower affinity of mAbs compared to IgE may lead to underestimation of the IgE-binding capacity of an allergen extract. For application of mAbs these potential pitfalls should be taken into consideration.

Allergens↗
PubMed1993

cDNA cloning of a major allergen from timothy grass (Phleum pratense) pollen; characterization of the recombinant Phl pV allergen.

We isolated a cDNA encoding a major grass pollen allergen from a timothy grass (Phleum pratense) pollen expression cDNA library using allergic patients' IgE. The complete cDNA encoded an allergen that binds IgE from about 80% of grass pollen-allergic patients. Significant sequence homology was found to other major grass pollen allergens from Kentucky bluegrass (Poa pratense) as well as from rye grass (Lolium perenne) which originally were believed to form different identities. Using different monoclonal and polyclonal antibodies raised against group V allergens we identified the recombinant protein as a group V allergen from timothy grass, Phl p V. In IgE-binding studies it is demonstrated that the rPhl p V allergen can be used to block binding of patients' IgE to natural group V isoallergens on two-dimensional immunoblots. IgE inhibition experiments show that up to 60% of grass pollenspecific IgE can be preadsorbed with the rPhl p V allergen from patients sera. The purified rPhl p V induced specific histamine release of blood basophils from grass pollen-allergic patients. This emphasizes the usefulness of the rPhl p V for diagnostic and therapeutic purposes and corroborates the view that specific diagnosis and therapy of type l allergy could be performed with a limited panel of relevant recombinant allergens.

Amino Acid Sequence↗
PubMed1993

Differential expression of IgE and IgG4 specific antibody responses in asymptomatic and chronic human filariasis.

A population of 164 adult individuals resident in an area endemic for Brugia malayi lymphatic filariasis has been studied for humoral immune responses to filarial parasites. Antibody levels to Ag extracted from adult worms were determined for each of the IgG subclasses, for IgM and for IgE. The dominant isotype of antifilarial antibody was IgG4, which represented 88% of total IgG in asymptomatic microfilaremics, most of whom possessed 100 to 1000 micrograms/ml of specific antibody of this subclass (geometric mean 762 micrograms/ml). Patients with chronic disease (elephantiasis), who were generally amicrofilaremic, had substantially higher levels of IgG1, IgG2, and IgG3, but a 3.4-fold lower geometric mean level of specific IgG4 (222 micrograms/ml) than asymptomatics with or without microfilaremia. In contrast, specific IgE antibody levels in cases of elephantiasis were on average 4.5 times higher than those found in the asymptomatic carrier state. The majority of microfilaremics were therefore typified by extremely high specific IgG4 concentrations and relatively low IgE reactivities, whereas clinical cases tended to show the reverse relationship. The possible roles of these isotypes and the implications of changing IgG4/IgE balances in disease are discussed.

Adolescent↗
PubMed1993

Properties of tree and grass pollen allergens: reinvestigation of the linkage between solubility and allergenicity.

In this study we reinvestigated the kinetics of allergen release from birch pollen (Betula verrucosa) and timothy grass pollen (Phleum pratense) using different protein extraction procedures, immunoblotting with specific antibodies and immune electron microscopy. Pollen allergens such as the major birch pollen allergen, Bet v I, the major timothy grass pollen allergens, Phl p I and Phl p V, group-II/III allergens from timothy grass and profilins were released rapidly and in large amounts from hydrated pollen. Within a few minutes pollen allergens could be detected in aqueous supernatants prepared from birch and grass pollen with serum IgE or specific antibodies. In parallel the allergen content in the pollen pellet fractions decreased. A nonallergenic protein such as heat shock protein 70 can be extracted in sufficient amounts only with harsh extraction procedures. Immune electron microscopy of dry and rehydrated birch pollens showed that after short hydration, the major birch pollen allergen, Bet v I, migrated into the exine and to the surface of intact pollen grains, whereas profilin, against which a lower percentage of patients is sensitized, was retained in the pollen grain. Comparing the amino acid composition and hydrophilicity of the tested allergens with a nonallergenic protein such as heat shock protein 70, no significant difference was noted. In agreement with earlier observations we conclude that the allergenic properties of proteins are rather linked to the amount and speed of solubility from airborne particles than to intrinsic properties.

Allergens↗
PubMed1992

Profilin is a cross-reactive allergen in pollen and vegetable foods.

Sera with IgE antibodies against grass pollen often contain IgE against vegetable foods. We investigated the role of the ubiquitous protein profilin in this cross-reactivity. Profilin was purified from Lolium perenne grass pollen by means of affinity purification with Sepharose-coupled poly(L-proline). This solid phase was also used as capturing agent for profilin from pollen and food extracts for application in a radioallergosorbent test. It was shown that profilin is an allergen in grass pollen and in a wide range of vegetable foods, like potato and celery. Within a grass-pollen-sensitive population, patients with IgE to vegetable foods have a high incidence of antibodies against profilin. IgE antibodies against grass pollen profilin were shown to be cross-reactive with respect to vegetable foods.

Allergens↗
PubMed1992

N-terminal amino acid sequence homologies of group V grass pollen allergens.

In an earlier study, we presented data regarding the immunoaffinity purification and N-terminal sequencing of a major pollen allergen from orchard/cocks-foot grass (Dactylis glomerata), now identified as the group V allergen Dac g V. In this paper, we have extended our investigations to include group V allergens from other grass species. Our data confirm the presence of group V-restricted characteristic N-terminal amino acid sequences containing a high alanine and hydroxyproline (P') rather than proline (P) content, and based upon two conserved elements (ADAGY and TPA/TP'A).

Allergens↗
PubMed1989

Characterization with monoclonal and polyclonal antibodies of a new major allergen from grass pollen in the group I molecular weight range.

We have purified a 24/25 kd allergen from orchard grass pollen (Dactylis glomerata) that has an allergenic potency similar to that of the major group I allergen. We provisionally named this allergen grass 4B1 after the monoclonal antibody used for its identification and purification. This monoclonal antibody was obtained by immunizing mice with whole Lolium perenne-pollen extract and by screening the antibody producing hybrids for reactivity with Dactylis glomerata-pollen extract. Grass 4B1 is physicochemically separable from the group I allergen. Polyclonal rabbit antibodies to grass 4B1 do not react with group I allergen or vice versa. Ninety-five sera with IgE antibodies to grass pollen were tested for IgE antibodies to grass 4B1, and greater than 90% was positive in this test. The median response to grass 4B1 was 70% of that to Lol p I.

Allergens↗
PubMed1986

Human IgM antibodies do not activate guinea-pig complement after interaction with soluble antigen.

Activation of guinea-pig complement by human IgM antibodies after interaction with a particulate antigen is well established. Human IgM antibodies directed against meningococcal group-C capsular polysaccharide, however, were not able to fix guinea-pig complement in a classical complement fixation test with soluble antigen. In the same test, human complement was readily activated by these antibodies. This inability of human IgM antibodies to activate guinea-pig complement after interaction with soluble antigen was confirmed in other antigen systems. In contrast, efficient activation of both human and guinea-pig complement was found with the same antigen in a particulate form.

Animals↗
PubMed1982

Glucose transport in Salmonella typhimurium and Escherichia coli.

We have investigated the claim by Schweiger and coworkers [Eur. J. Biochem. 102(1979)231-236] that glucose transport in Escherichia coli is catalyzed mainly by an ATP-dependent transport system instead of the phosphoenolpyruvate:sugar phosphotransferase system. A major argument was the differential effect of 2,4-dinitrophenol on glucose uptake and the transport of its non-metabolizable analogue, methyl alpha-glucoside. Whereas the first was inhibited, the second was stimulated. When subsequent glucose metabolism is prevented by introducing mutations that eliminate glucose 6-phosphate metabolism, 2,4-dinitrophenol does not inhibit glucose transport. Although dinitrophenol inhibited in wild-type cells of E. coli and Salmonella typhimurium the uptake of 14C label in cells using [U-14C]glucose as a substrate, disappearance of glucose from the medium was not affected or only slightly affected. Since uptake represents a combination of transport and subsequent metabolism, retention of labelled material depends on the balance of incorporation of label in cellular material and efflux of labelled compounds. Our experiments show that inhibition of the uptake of labelled glucose by 2,4-dinitrophenol is not due to inhibition of transport as suggested by Schweiger and coworkers, but to increased efflux of labelled compounds such as acetate and pyruvate. In addition, incorporation of label in cellular material is lowered by dinitrophenol. Inhibition of uptake by dinitrophenol is found with many labelled sugars, including mannitol, galactose and glycerol, the transport of which is energized in quite different ways. We conclude that there is no need to postulate a novel ATP-driven system for glucose transport. All results can be explained with the phosphoenolpyruvate:glucose phosphotransferase system as the main if not sole glucose transport system.

2,4-Dinitrophenol↗
PubMedDate not supplied

The apparent monovalency of human IgG4 is due to bispecificity.

A hypothesis is put forward to explain the apparent monovalency of human IgG4. It is based upon the known instability of the IgG4 hinge. IgG4 is secreted as a regular bivalent antibody, but after secretion interacts with another IgG4 molecule. This interaction results in the exchange of half molecules (a combination of one heavy chain and one light chain) between the two IgG4 molecules. The postulated bispecific IgG4 antibodies can indeed be found in selected human sera following repeated immunization with two non-crossreacting antigens.

Antibodies, Bispecific↗