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Biomedical subjects

S B Lehrer

Publications and source records attributed to S B Lehrer.

At least 37 records · Page 2Linked to original sources
PubMed1999

IgE antibody response to vertebrate meat proteins including tropomyosin.

BACKGROUND: Although meat is a main source of proteins in western diets, little information is available regarding allergy to vertebrate meats or the allergens implicated in these reactions. OBJECTIVE: To evaluate the in vitro IgE antibody response to different vertebrate meats in suspected meat-allergic subjects, as well as the possible role of tropomyosin in meat allergy and to analyze the cross-reactivity between vertebrate meats and the effect of heating on the IgE-binding to meat proteins. METHODS: Fifty-seven sera from suspected meat-allergic subjects were tested by grid blot to extracts of beef, lamb, pork, venison, chicken, and turkey and to four mammalian tropomyosins of different origins. RESULTS: Meat-allergic subjects have IgE antibodies to proteins in different mammalian meats (43/57 subjects); cross-reactivity with avian meat was limited: less than 50% (19/43) of meat positive sera reacted to chicken. In contrast, most of the poultry-positive sera also reacted to different mammalian meats. In general, there was stronger IgE reactivity to raw meats in comparison to cooked meats; an exception was six cases in which IgE reactivity to cooked poultry was stronger. Weak IgE reactivity to tropomyosin was detected in only 2/57 sera tested. CONCLUSIONS: Suspected meat-allergic subjects have serum IgE directed to meat proteins. In vitro cross-reactivity among mammalian meats appears to be important, while cross-reactivity to poultry is limited indicating mammalian-specific proteins. Although cooking in general denatures meat proteins rendering them less allergenic, in some cases the process of cooking may result in the formation of new allergenic moieties. The muscle protein tropomyosin is not an important vertebrate meat allergen.

Adolescent↗
PubMed1999

Fish allergy: is cross-reactivity among fish species relevant? Double-blind placebo-controlled food challenge studies of fish allergic adults.

BACKGROUND: Allergic reactions to fish are a common cause of food allergy in many areas of the world where fish is a major source of protein. Although different species of fish may be consumed, possible cross-reactivity has received limited investigation. OBJECTIVE: The aim of this study was to assess potential cross-reactivity to different species of fish species using double-blind, placebo-controlled food challenges (DBPCFC) in fish-allergic adults and to compare skin test and RAST reactivity with the challenge response. METHODS: Nine skin prick test and/or RAST-positive adult individuals with histories of an immediate-type reaction following fish ingestion were challenged with different fish species using double-blind, placebo-controlled food challenge. RESULTS: Of a total of 19 double-blind, placebo-controlled fish challenges performed, 14 challenges (74%) resulted in the induction of objective signs that were consistent with an IgE-mediated response. The most common sign observed was emesis (37%); the most prevalent subjective symptoms reported were compatible with the oral allergy syndrome (84%). Three subjects reacted to at least three fish species and one subject reacted to two fish species tested. In regard to the positive challenges, predictive accuracy of skin prick test and RAST was 84% and 78%, respectively. CONCLUSION: Our results indicate that clinically relevant cross-reactivity among various species of fish may exist. Advising fish-allergic subjects to avoid all fish species should be emphasized until a species can be proven safe to eat by provocative challenge.

Adult↗
PubMed1999

Tropomyosin: an invertebrate pan-allergen.

Among food allergens, crustaceans, such as shrimp, crab, crawfish and lobster, are a frequent cause of adverse food reactions in allergic individuals. The major allergen has been identified as the muscle protein tropomyosin. This molecule belongs to a family of highly conserved proteins with multiple isoforms found in both muscle and nonmuscle cells of all species of vertebrates and invertebrates. Its native structure consists of two parallel alpha-helical tropomyosin molecules that are wound around each other forming a coiled-coil dimer. Allergenic tropomyosins are found in invertebrates such as crustaceans (shrimp, lobster, crab, crawfish), arachnids (house dust mites), insects (cockroaches), and mollusks (e.g. squid), whereas vertebrate tropomyosins are nonallergenic. Studies of cross-reactivities among crustaceans and the high degree of sequence identity among them suggest that tropomyosin is probably the common major allergen in crustaceans. Furthermore, immunological relationships between crustaceans, cockroaches and housedust mites have been established and may suggest tropomyosin as an important cross-sensitizing pan allergen.

Allergens↗
PubMed1997

Quantification of the major brown shrimp allergen Pen a 1 (tropomyosin) by a monoclonal antibody-based sandwich ELISA.

BACKGROUND: Among 13 allergens found in extracts of cooked brown shrimp (Penaeus aztecus) the 36 kd muscle protein tropomyosin has been identified as the only major shrimp allergen (Pen a 1). Cross-reacting molecules with similar molecular weights were detected in other crustacea species such as crab, lobster, and crawfish. Because Pen a 1 and Pen a 1-like allergens are important in crustacea allergy, the aim of this study was to develop a monoclonal antibody (mAb)-based sandwich ELISA to quantify Pen a 1 and to evaluate Pen a 1 levels in four commercial shrimp, crab, and lobster extracts. METHODS: Two Pen a 1-specific mAbs with different epitope specificities were selected. ELISA plates coated with captured mAb 3.2 were incubated with samples containing Pen a 1. Bound Pen a 1 was detected by a combination of biotinylated mAb 4.9.5 and alkaline phosphatase-labeled streptavidin. RESULTS: The optimized sandwich ELISA could detect Pen a 1 concentrations ranging from 4 to 125 ng/ml. Four commercial shrimp extracts demonstrated a 40-fold difference in Pen a 1 levels (24 to 920 microg/ml). Crab and lobster extracts contained detectable levels of Pen a 1-like proteins. No reactivity to cockroach, house dust mite, oyster, codfish, or peanut extracts was detected, which indicates that the developed assay is crustacea-specific. CONCLUSION: A sensitive sandwich assay was developed to quantify Pen a 1. This assay will be helpful to standardize shrimp extracts in regard to the content of the major allergen, Pen a 1, and to study cross-reactivities among and evaluate occupational exposure to different crustacea species.

Allergens↗
PubMed1997

Comparison of pediatric and adult IgE antibody binding to fish proteins.

BACKGROUND: Allergic reactions to fish are a common cause of food allergy. OBJECTIVE: We compared the binding of pediatric and adult fish-allergic patient IgE antibodies to fish proteins. METHODS: Clinical histories of fish allergy were confirmed by prick skin tests, RAST and if possible, with blinded oral food challenges. The patients included five children with severe allergic reactions to catfish (4/5), cod (1/5), and tuna (1/5) and five adults with severe allergic reactions to catfish (5/5), cod (2/5), snapper (3/5), and tuna (2/5). Extracted proteins from catfish, cod, snapper, and tuna were separated with SDS-PAGE. IgE immunoblots and immunoblot inhibition studies were performed using serum sample from these patients. RESULTS: Multiple fish proteins ranging from 12 to 45 kD from the four fish extracts were identified by SDS-PAGE. A major protein (12.5 kD) was present in all fish extracts except for raw tuna. Immunoblots using individual pediatric and adult serum samples revealed that the major IgE binding was to the 12.5-kD protein from catfish, cod, and snapper. The immunoblot with tuna using serum from a pediatric patient with isolated tuna anaphylaxis revealed an IgE binding protein band at 40 kD. Preincubation of serum samples from two separate fish-allergic patients with 1 mg of cod fish extract completely inhibited IgE binding to the 12.5-kD fish protein in subsequent immunoblots. CONCLUSIONS: Pediatric and adult fish-allergic patients have similar in vitro IgE binding to a 12.5-kD protein from fish extracts. This protein is immunochemically similar to Gad c I, the major allergen in cod.

Adult↗
PubMed1996

IgE and monoclonal antibody reactivities to the major shrimp allergen Pen a 1 (tropomyosin) and vertebrate tropomyosins.

Pen a 1, the major shrimp allergen from brown shrimp Penaeus aztecus has been identified as the muscle protein tropomyosin. To identify Pen a 1 IgE binding sites, the reactivities of Pen a 1-specific monoclonal antibodies (mAbs) and shrimp-allergic subjects' IgE to shrimp and homologous mammalian tropomyosins were analyzed. Pen a 1, purified by preparative SDS-PAGE and commercially obtained porcine, bovine and rabbit tropomyosin were cleaved by CNBr or digested by endoproteinases Lys-C, Glu-C, trypsin, Arg-C and chymotrypsin. Reactivities of Pen a 1-specific mAbs and IgE to the resulting peptides were analyzed by dot blot and immunoblotting. The dot blot analysis showed that mAbs and IgE antibodies did not react with any of the mammalian tropomyosins. The immunoblot analysis showed that all Pen a 1 digests bound IgE or mAbs. However, not all peptides in each digest possessed an IgE binding site. IgE binding intensity and frequency varied by subject and peptide digest. IgE and mAb reactivity patterns were similar but no mAb reproduced the IgE binding patterns indicating that subject' IgE bound some epitopes that were not recognized by the Pen a 1-specific mAbs. These studies suggest that IgE-binding epitopes are restricted to certain parts of the Pen a 1 molecule, Pen a 1 may have several similar epitopes, and that Pen a 1 epitopes do not appear to be located in the highly homologous parts of the tropomyosin molecule.

Allergens↗
PubMed1996

Identification of the first major allergen of a squid (Todarodes pacificus).

BACKGROUND: In Japan, squid is an important seafood, and some patients with food allergies are sensitive to squid. There has been no report, however, describing the major allergens of squid. OBJECTIVE: To characterize squid allergens, we isolated a major allergen from the Pacific flying squid (Todarodes pacificus) and compared it with a major allergen from a shrimp (Penaeus orientalis). METHODS: The major squid and shrimp allergens were isolated by column chromatography on diethylaminoethyl-Sepharose (Pharmacia, Uppsala, Sweden), hydroxylapatite, and Sephacryl S-300 (Pharmacia). The IgE reactivity of the isolated allergens was assessed by immunoblotting. The cross-reactivity between the squid and shrimp allergens was examined by use of mouse polyclonal and monoclonal antibodies to the major allergens. Amino acid sequence analyses of the isolated allergens were done. RESULTS: The isolated squid allergen is a 38 kd, heat-stable protein. IgE antibody binding to the purified squid allergen was demonstrated by immunoblotting. Cross-reactivity between major squid and shrimp allergens was demonstrated with sera from patients allergic to squid or shrimp or with allergen-specific monoclonal antibodies. The amino acid sequence analysis of the major squid allergen showed a marked homology with tropomyosin from blood fluke planorbid (Biomphalaria glabrata), which is a common vector snail of Schistosoma mansoni. CONCLUSION: This 38 kd protein is a major allergen of the squid, Todarodes pacificus, and is believed to be squid muscle protein tropomyosin. We named it Tod p 1 according to International Union of Immunological Societies allergen nomenclature regulation.

Allergens↗
PubMed1996

Immunopathogenesis of fish allergy: identification of fish-allergic adults by skin test and radioallergosorbent test.

BACKGROUND: As the consumption of fish increases in the United States, the importance of allergic reactions to fish has become clear. Since most previous studies on fish allergy have focused on children reacting mainly to codfish, there is a need to investigate allergic reactions to other fish in adults. OBJECTIVE: To identify fish-allergic adults, and to assess cross-reactivity among different species of fish by RAST inhibition. METHODS: Thirty-nine individuals who reported fish allergy were selected for study; 32 (82%) were atopic as defined by two or more positive skin tests to common inhalant allergens and a history of allergic reactions and 33 (85%) experienced allergic symptoms within 30 minutes after ingesting fish. The most frequently reported symptoms were hives (69%), itching (69%), and wheezing/chest tightness (54%). Study subjects were skin tested with fish extracts and their sera assayed for IgE antibodies to different fish species. RESULTS: Thirty-six (92%) of the subjects tested had a positive skin test to at least one of 17 fish extracts tested; 9/35 (26%) reacted to all 17 extracts. Of the atopic (two or more positive skin tests to common inhalant allergens plus a personal and/or family history of allergy) and nonatopic fish-tolerant controls, 20/26 (77%) reacted by skin test to one or more fish extracts tested; the most prevalent positive reaction was to anchovy (73%). A significant correlation (P < .01) was observed between skin test reactivity of fish-allergic subjects to most fish extracts and fish RAST reactions. Radioallergosorbent inhibition testing demonstrated significant cross-reactivity among pollack, salmon, trout, and tuna; and between mackerel and anchovy. CONCLUSION: These results suggest that fish-allergic subjects may be clinically sensitive to more than one species of fish. Skin test reactivity to fish by itself is not an adequate criterion for the confirmation of clinically relevant fish allergy; consequently, fish-allergic subjects with positive skin tests to several fish species should exercise caution when eating fish until tolerance can be demonstrated by double-blind, placebo-controlled food challenge, at the patient's earliest convenience.

Adult↗
PubMed1996

Why are some proteins allergenic? Implications for biotechnology.

In recent years, a number of agricultural crops have been developed with recombinant DNA technology. Because the transferred genes code for proteins that are ordinarily not present in these particular foods, there is concern about the potential allergenicity of these new crop varieties. Foods contain many proteins; however, only a small fraction are allergens. Although the structural properties of proteins that cause allergic reactions have not been characterized completely, known food allergens in general have molecular weights between 10 and 70 kDa, stimulate the immune response (induce the production of allergen-specific IgE), and are stable molecules that are resistant to processing, cooking, and digestion. Although any type of food is potentially allergenic, the majority of food allergies are caused by a small group of foods (cows' milk, nuts, legumes, eggs, seafood). Cross-reactivities occur within a given food group and between foods and seemingly unrelated proteins. Even though most transgenic foods are considered safe, biotechnological manipulation can affect crop allergenicity. The safety evaluation of transgenic foods is relatively easy when the allergenicity of the gene sources are known. The recombinant food can be assayed using traditional in vitro inhibition assays. Recently, reduced allergen content of biotechnologically altered rice was shown. In contrast, increased allergenicity was demonstrated in transgenic soybeans after a methionine- and cystine-rich protein from Brazil nuts, identified as a major Brazil nut allergen, was expressed in soybean to increase its content of sulfur-rich amino acids. The most difficult issue regarding transgenic food allergenicity is the effect of transfer of proteins of unknown allergenicity. The challenge is to determine whether these proteins are allergenic as there is no generally accepted, established, definitive procedure to define or predict a protein's allergenicity. Comparing the structures of the transferred protein with known allergens and allergen epitopes could be one approach. Additionally, Th-2 cell stimulation, the production of IL-4, and IgE antibody induction in animal models may help to evaluate the potential allergenicity of a protein. In conclusion, there is no evidence that recombinant proteins in newly developed foods are more allergenic than traditional proteins. The evidence suggests that the vast majority of these proteins will be completely safe for the consumer. The concern is that if a few transgenic foods cause serious allergic reactions, this could undermine the public's confidence in such products. It is essential that proper guidelines are established and tests are developed to assure that this will not occur.

Allergens↗
PubMed1996

Principles and characteristics of food allergens.

Food allergens are typically proteins that are resistant to digestion, acid, and heat treatments. However, some notable exceptions exist. The amount of these proteins needed to elicit an allergic response in previously sensitized individuals is quite low (milligram amounts). The allergenicity of specific proteins derived from known allergenic sources can be determined, whereas the potential allergenicity of proteins derived from sources of unknown allergenicity is much harder to assess.

Allergens↗
PubMed1996

Occupational asthma caused by aromatic herbs.

We describe a subject with occupational asthma caused by several aromatic herbs: thyme, rosemary, bay leaf, and garlic. The diagnosis was confirmed by several inhalation challenges in the laboratory. Although immediate skin reactivity was demonstrated to the herbs the subject reacted to by inhalation, RAST showed that garlic was the most potent allergen by weight, the other herbs showing less reactivity. These aromatic herbs, bay leaf, thyme, and rosemary, should be included among agents causing occupational asthma in the food industry.

Adult↗
PubMed1995

Identification of important allergens in German cockroach extracts by sodium dodecylsulfate-polyacrylamide gel electrophoresis and western blot analysis.

BACKGROUND: Despite recent advances in the purification and characterization of cockroach allergens, identification of clinically important allergens and their source have not been completely elucidated. This study investigated the allergen content of German cockroach (Blattella germanica) whole body (GWBE) and fecal (GFE) extracts. METHODS: Sera from 37 subjects with asthma, with positive skin test results to cockroach, were used for RAST and Western blot (after sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE] under reducing conditions); this serum panel is the largest used to date for cockroach allergen analysis. RESULTS: RAST reactivity to GWBE and GFE were highly correlated (r = 0.882, p < 0.001). SDS-PAGE and Western blotting showed that GWBE and GFE had similar patterns of IgE binding. Furthermore, Western blot inhibition investigations revealed that either GWBE or GFE could almost completely inhibit the reactivity of the other extract, SDS-PAGE and Western blotting demonstrated in both extracts numerous bands that displayed a high prevalence of IgE binding. Protein bands at 67, 50, 45, and 36 kd bound more than 50%, and the band at 60 kd bound approximately 80% of the sera tested. CONCLUSIONS: In summary, this investigation identified German cockroach allergens, established their relative importance by prevalence of reactivity to a large serum panel, and demonstrated that cockroach feces possess significant allergenic activity. Five allergens identified demonstrated reactivity with up to 50% to 80% of the 37 subjects' sera tested.

Allergens↗
PubMed1995

Occupational IgE-mediated sensitization and asthma caused by clam and shrimp.

BACKGROUND: To confirm occupational asthma caused by clam and shrimp in a food company worker, the following investigation was planned in 60 other exposed workers (56 participants). METHODS: Before the production period of clam and shrimp, a medical and occupational questionnaire was carried out and skin and RAST testing were done with common inhalants and clam, shrimp, crab, and lobster extracts. During the production period, environmental monitoring was performed with personal and general samplers; inhalation testing with methacholine was proposed to subjects with immediate skin reactivity to clam, shrimp, or both. After the production period, all subjects with an immediate skin reactivity to clam, shrimp, or both and either a history of rhinoconjunctivitis, asthma, or bronchial hyperresponsiveness were seen by a specialist. RESULTS: Including the index case in whom occupational asthma to clam and shrimp had been confirmed, four (7%) subjects had a history of rhinoconjunctivitis and two (4%) had a history of asthma during the period of clam production, whereas three (5%) subjects had rhinoconjunctivitis and two (4%) had asthma during the shrimp production. Three (5%) subjects had immediate skin reactivity to clam, and nine (16%) subjects to shrimp. Four (7%) subjects had increased specific IgE antibodies (RAST binding > or = 3%) to clam and eight (14%) to shrimp. Significant associations were found between immunologic reactivity to clam and shrimp on the one hand and to crab and lobster on the other. Environmental monitoring demonstrated clam and shrimp on the air sampling filters. Occupational asthma caused by clam was confirmed by specific inhalation challenges in one subject in addition to the index case. These two subjects had skin reactivity and increased specific IgE antibodies to clam, shrimp, or both. CONCLUSION: By including the initial subject, the prevalence of immediate sensitization is 5% to 7% to clam and 14% to 16% to shrimp. Two (4%) subjects had occupational asthma caused by clam, and one (2%) had occupational asthma caused by shrimp.

Adult↗