Allergen immunotherapy

Allergen immunotherapy plays an important role in the treatment of allergic diseases and asthma. This article is a brief review of the current approaches, including patient and allergen selection, routes of administration, and use of standardized allergen vaccines. New approaches offering potentially useful strategies based on recent studies of T-cell epitopes, cytokines, and anti-IgE and DNA vaccines also are considered.

Safety of fexofenadine in children treated for seasonal allergic rhinitis

BACKGROUND

The incidence of allergic rhinitis in children is increasing.

OBJECTIVE

To evaluate the safety of fexofenadine HCI in children ages 6 through 11 years for treatment of seasonal allergic rhinitis.

METHODS

Two large, double-blind, randomized, placebo-controlled, parallel studies with identical protocols included patients with a positive skin test to fall allergen(s) and allergic rhinitis symptoms. Patients were randomized to receive fexofenadine 15, 30, or 60 mg or placebo twice daily for 2 weeks after a 1-week placebo lead-in. Safety was evaluated through adverse event reporting, electrocardiograms, and pre- and posttreatment laboratory panels and physical examinations.

RESULTS

A total of 875 patients from both studies were eligible for safety analyses. Ten patients (5 on placebo, 5 on fexofenadine) discontinued because of an adverse event; no event that resulted in discontinuation was judged to be caused by study medication. Incidence of adverse events was similar in active and placebo groups, and did not increase with increasing fexofenadine dose: 36.2% (83 of 229) in the placebo group versus 35.3% (79 of 224), 36.8% (77 of 209), and 34.7% (74 of 213) in the 15, 30, and 60 mg twice-daily fexofenadine groups, respectively. Headache was the most commonly reported adverse event (6.6%, 8.0%, 7.2%, and 9.4% in the placebo, 15, 30, 60 mg twice-daily fexofenadine groups, respectively). Clinical, vital sign, electrocardiogram, and laboratory measures were similar in active and placebo groups. There was no statistically significant mean change from baseline in any electrocardiogram parameter after fexofenadine treatment.

CONCLUSIONS

Fexofenadine, 15, 30, and 60 mg twice daily, was safe and well tolerated in this large pediatric patient population.

Allergenic materials in the house dust of allergy clinic patients

INTRODUCTION

Environmental agents including animal, fungal, tree, and weed antigens are known to cause allergic rhinitis and asthma. The following study was performed to measure the antigen concentration of several of these in house dust of children seen in an allergy clinic. Comparisons are made between household allergen levels of children seen for asthma and children seen for other reasons.

METHODS

Dust samples were solicited from patients in a pediatric allergy specialty clinic and other individuals associated with the clinic. Persons submitting dust were asked to complete a questionnaire describing their house. Samples were extracted, centrifuged, and filtered for sterility. Samples were stored in 50% glycerol at -20 degrees C. Specific antigens for Alternaria, Cladosporium, Aspergillus, Candida, Dermatophagoides farinae, cat, dog, oak, fescue, ragweed, plantain, and cockroach were measured using inhibition assays developed with whole antigen extract. Allergens Der p1, Der f 1, Alt a 1, and Alt a 70 kD were measured using double monoclonal antibody assays.

RESULTS

Significant concentrations of whole antigen from cat, dog, oak, Alternaria, and Cladosporium were detected. Between 0.1 and 18 microg of Der f1 and Der p1 per gram of dust were also measured. Alt a 1 and Alt a 70 kD levels varied between 3.0 and 1000 U/g of dust. Significant positive correlations were observed in levels of dust mite and Alternaria allergen for patients with an evaluation of asthma.

CONCLUSIONS

We found measurable levels of fungal antigens (Alternaria, Cladosporium), mite antigens, and animal antigens (dog and cat) in the majority of dust samples in this self-selected set of allergy clinic patients. Specific allergens Alt a 1, Alt a 70kD, and Der p 1 were significantly higher in the homes of asthmatic patients when compared with patients seen for reasons other than asthma. These studies support the hypothesis that fungal allergen exposure is an important component in the pathogenesis of the clinical condition known as asthma.

Hourly variation of airborne ragweed pollen in Kansas City

INTRODUCTION

Ragweed pollen is one of the major causes of allergic rhinitis in the midwest United States. Previous studies have demonstrated that ragweed pollen production begins after sunrise and airborne pollen levels peak several hours later. Variations in this pattern that may be of clinical importance within a small region and the effect of weather on these variations have not been investigated.

METHODS

Volumetric pollen collectors were stationed at four sites around the metropolitan area. Ten-minute grab samples were taken at each location every 2 hours for continuous 24-hour periods during the 1997 ragweed season. The downtown location had a weather station that logged meteorological conditions at hourly intervals during this time. Ragweed pollen grains were counted microscopically at 400 x. Uninterrupted data covering at least 20 days during the season were evaluated for each collection site.

RESULTS

The lowest ragweed pollen counts occur at 6:00 AM and the highest occur at noon for both suburban and urban sites. Rainfall was seen to be the most influential weather-related factor. Significant rainfall events effectively removed pollen grains from the air.

CONCLUSIONS

Though ragweed pollen emission begins at 6:00 AM, peak pollen exposure occurs at midday. This observation is in agreement with many other studies. The myth that highest ragweed exposure occurs in the early morning hours is not supported by this or previous studies.

Efficacy of a single diagnostic test for sensitization to common inhalant allergens

BACKGROUND

UniCAP Phadiatop is a single laboratory test designed to determine the presence or absence of specific IgE to a variety of common inhalants. Its purpose is to aid in the differentiation of patients with symptoms attributable to allergic disease from other common causes.

METHODS

Consecutive children and adolescent patients (n = 145) at two centers were examined by having their history and physical examination performed by two board certified allergists. Their conclusions along with skin prick tests and specific IgE measurements regarding seven common inhalants (mite, oak, ragweed, grass, dog, cat, Alternaria) were compared with UniCAP Phadiatop test results. This was done using concordance of all test results. Attempts to resolve test discrepancies, when found, included specific RAST inhibitions, total IgE values, and physicians' judgment after testing.

RESULTS

All patients with resolved diagnoses (143 of 145, 103 positive and 40 negative) were identified correctly by the UniCAP Phadiatop test. Skin test results and specific IgE measurements correlated well, but neither correlated well with the history by itself, suggesting a minimal false-positive component of the history of 23%. UniCAP Phadiatop results demonstrated a quantitative relationship between the patient's score and the amount of IgE specific to these individual allergens.

CONCLUSIONS

The UniCAP Phadiatop test was shown to be highly sensitive and specific in differentiating individuals who are sensitized to common inhalants from those who are not. This test is recommended to all physicians as an aid in diagnostic and referral decisions for patients suspected of having an inhalant allergic diathesis.

Comparison of the Burkard and Allergenco MK-3 volumetric collectors

BACKGROUND

The Burkard sampler is a widely used volumetric pollen and spore collector, in part, because it is wind-oriented, it has consistent flow characteristics, and it permits time-discrimination of collected particles. Its main disadvantages are that it is heavy, expensive, and visual counting is very time-consuming. A less-expensive volumetric collector with time discrimination capabilities could permit more widespread particle counting which would enhance our understanding of aerobiology.

OBJECTIVE

The objective of this study is to compare the collection recoveries of the Burkard sampler with a less-expensive non-wind oriented collector, the Allergenco MK-3, under various wind speeds.

METHODS

Pollen and spore counts were compared on 20 sampling days during the spring pollen season using a Burkard and Allergenco MK-3 located next to each other on the roof of a 5-story hospital building. A weather station was placed nearby and wind velocity was concurrently measured.

RESULTS

The median wind velocity was 6 miles/hour with a maximum of 35 miles/hour. The Burkard and Allergenco MK-3 collectors displayed similar collection characteristics at all wind velocities for both pollen and spores. The Burkard gave lower counts than the Allergenco when absolute particle counts were low and similar values at higher absolute counts.

CONCLUSIONS

Given our data, we conclude that ambient wind speed has no significant effect on collection efficiency at velocities commonly found on the roof of our hospital and that the collection characteristics of the Burkard and Allergenco MK-3 are comparable.

Comparison of outdoor allergenic particles and allergen levels

INTRODUCTION

Spore and pollen counts have been used traditionally to determine aeroallergen exposure. Using a liquid based collector and enzyme immunoassays, we have developed methods for measuring airborne allergen concentrations. In this work we test the hypothesis that airborne allergen concentrations are directly related to spore and pollen counts.

METHODS

Test samplers used included a high-volume cyclonic liquid impinger (SpinCon) and a standard spore trap (Burkard). Samples were collected on a weekly basis from May to October and were analyzed microscopically for spores and pollen grains. The liquid samples were analyzed by enzyme-linked immunoassay for the presence of allergens from Alternaria, Cladosporium, Aspergillus, oak, fescue, ragweed, and plantain. Specific Alternaria allergens Alt al and GP70 also were measured.

RESULTS

Pollen counts for the SpinCon and Burkard collectors were similar, though spore counts were lower with the SpinCon. Detectable amounts of three of the seven allergenic species including fescue, ragweed, and Alternaria were present in air samples. Concentrations of pollens were seen in their respective seasons while fungal allergen levels varied throughout the period. Allergen levels generally agreed with particle counts, however peak allergen levels and peak particle counts for individual species did not correlate well.

CONCLUSIONS

At flow rates of 236 L/min, the SpinCon is comparable to the Burkard for counting airborne pollen and spores. Samples collected by the SpinCon permit quantitative determination of allergen levels in outdoor air. The poor correlation between measured airborne allergen and related particles indicates the potential for significant allergen exposure in the absence of identifiable particles in air.

Infant pulmonary hemorrhage in a suburban home with water damage and mold (Stachybotrys atra)

The American Academy of Pediatrics recently issued guidelines regarding the potential toxic effect of indoor molds. We now report another case of an infant with pulmonary hemorrhage whose residential environmental assessment revealed the presence of the toxigenic mold Stachybotrys atra. We used a questionnaire to identify environmental factors that could predispose the home to fungal contamination. We collected air samples from multiple locations in the home that we felt would reflect areas of relevant exposure. Surface samples were collected with a piece of transparent tape for semiquantitative measurement of spores present. We classified spores into their respective genera based on shape, size, and color. We also measured mycotoxin levels. Air sampling revealed significantly elevated total spore counts in the patient's bedroom and in the attic. Aspergillus/Penicillium species were predominant. Stachybotrys spores were found in the air sampled in the patient's bedroom, as well as from surfaces sampled in the patient's closet and the attic ceiling. Additionally, a small patch of Stachybotrys-contaminated area in the closet ceiling was sent for mycotoxin analysis. This material proved to be highly toxigenic. As the link between the presence of Stachybotrys in the home and pulmonary hemorrhage in infants increases, further efforts should be made to educate physicians, health care providers, and new parents about the potential toxic effects of this mold.

Monoclonal antibody-based assay for Alt a1, a major Alternaria allergen

BACKGROUND

Allergenic materials from Alternaria are significant causes of human disease. One 31-kD glycoprotein, designated Alt a1, has been described previously as being a significant allergen.

OBJECTIVES

The purpose of this study is to characterize purified Alt a1 and to provide a method for measuring it in laboratory and environmental samples.

METHODS

Monoclonal antibodies directed to the purified allergen were produced and used to construct a double monoclonal assay for Alt a1. The purified allergen detected by this assay was tested for IgE binding in vitro and in vivo.

RESULTS

Purified allergen detected by this assay was shown to bind IgE from patients sensitive to Alternaria and gave a positive skin test in 15 of 16 patients skin test reactive to commercial Alternaria extracts. The assay is sensitive to Alt a1 concentrations as low as 0.2 microg/nmL and is very specific for the allergen. The three commercial Alternaria extracts assayed contained measurable quantities of the allergen varying from 12 to 84 microg/mL.

CONCLUSIONS

Alt a1 is a significant Alternaria allergen. The ability to measure this allergen may assist in standardizing Alternaria extracts and lead to an understanding of the significance of exposure to this allergen.

Northern blot identification of mRNA containing sequence for protein allergen, Alt a1, in eight strains of Alternaria alternata

BACKGROUND

Concentrations of Alt a1, a major allergen from Alternaria alternata extracts, exhibit significant batch-to-batch variability. This variability may result from basic strain-related genetic differences or from environmental influences such as growth conditions or extraction methods.

OBJECTIVE

The objective of this work is to determine if strain-to-strain allergen variability in Alternaria alternata, Alt a1 allergen occurs at the nucleic acid level.

METHODS

We compared the content of mRNA for a segment known to contain sequence coding for the reported N-termini of this allergen in eight strains of Alternaria obtained from three individual sources grown under identical conditions. RNA was extracted from rapidly growing mycelia and analyzed by northern blot analysis for the content of a specific segment containing sequence for the Alt a1 allergen. Blots were also analyzed for the content of a specific 5.8S rRNA segment.

RESULTS

The size of the mRNA for this protein was about 700 bases. Sequence for the specific segment was found in all of the eight strains tested. When normalized for extraction variabilities using the content of 5.8S rRNA, the calculated concentrations of Alt a1 mRNA of seven of the eight strains were similar.

CONCLUSIONS

The results of these experiments suggest that this Alt a1 related allergen sequence is found in many strains of Alternaria and that variabilities in allergen protein content noted previously result from posttranslational events.

Development of mupirocin resistance among methicillin-resistant Staphylococcus aureus after widespread use of nasal mupirocin ointment

All methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from colonized or infected patients in a 625-bed public teaching hospital during an epidemic, and for 3 years thereafter, underwent susceptibility testing to mupirocin. Mupirocin resistance among MRSA increased markedly over this period (1990, 2.7%; 1991, 8.0%; 1992, 61.5%; 1993, 65%) in association with increased use of mupirocin ointment as an adjunct to infection control measures.

Evaluation of four bioaerosol samplers in the outdoor environment

INTRODUCTION

A comparative evaluation of four air samplers was performed using bioaerosol collection in the outdoor environment.

METHODS

Test samplers used included a Rotorod, a Kramer-Collins suction trap, an all-glass impinger (AGI-30), and a high-volume cyclonic liquid impinger (SpinCon). All samples were analyzed microscopically for spores and pollen. The two collectors providing a liquid sample (AGI-30 and SpinCon) also were analyzed for specific allergen content by enzyme-linked immunoassay.

RESULTS

The SpinCon collected a larger number of spores than the other devices. The number of spores collected by this unit per volume of air sampled was comparable to the AGI-30. The Rotorod and Kramer-Collins collected a lower number of spores per unit of air but collected a larger number of pollen grains per volume sampled. Alternaria allergens Alt a I and GP70 were collected by both liquid impingers; however, the SpinCon collected more Alt a I and the AGI-30 collected more GP70.

CONCLUSIONS

The SpinCon is a device that is capable of efficiently sampling a high volume of air and concentrating it in a form that can be analyzed for the presence of spores and fungal allergens. It is less useful for collecting intact pollen grains. Pollen allergen quantitation has not yet been performed on the SpinCon effluent.

Rush immunotherapy: experience with a one-day schedule

INTRODUCTION

Rush immunotherapy is a method for rapidly desensitizing patients to inhalant allergens. The frequency of systemic reactions during rush immunotherapy is similar to conventional immunotherapy when premedication is used. The most rapid protocol for rush immunotherapy reported to date requires one and one-half days which is inconvenient to patients and clinic schedules. To improve this situation and decrease the cost of giving rush immunotherapy, we have developed a 1-day protocol.

METHODS

for this ongoing study, 22 allergic patients received rush immunotherapy consisting of eight injections over six hours followed by two hours of observation in an outpatient clinic. Five had rhinitis and the rest has asthma, seven of whom were steroid-dependent. All were premedicated with astemizole, ranitidine, and prednisone for three days including the day of rush immunotherapy, and peak expiratory low rates were monitored.

RESULTS

Systemic reactions were seen in five of 22 (23%). They occurred following the sixth injection (1), seventh injection (2), or the final one (2) and consisted primarily of rhinitis or pulmonary symptoms with one episode of mild anaphylaxis. A systemic reaction was seen in only one steroid-dependent asthmatic patient. A local reaction preceded a systemic reaction in only one patient. All but three reached a maintenance dose in one day. All systemic reactions responded to epinephrine and all patients could go home after rush immunotherapy. Only one patient had a systemic reaction during the three months after rush immunotherapy.

CONCLUSION

One day rush immunotherapy is tolerated by most patients with a systemic reaction rate comparable to conventional immunotherapy. All patients were able to reach a maintenance dose months sooner than weekly schedules. With refinement of this procedure, rush immunotherapy may become a widely used method for desensitizing patients with inhalant allergens, and could make immunotherapy less expensive and more convenient.

Production of a recombinant protein from Alternaria containing the reported N-terminal of the Alt a1 allergen

Allergen content of extract derived from Alternaria is somewhat variable. Allergenic molecules from Alternaria that appear as differing molecular size bands on IgE probed immunoblots may have a great deal of sequence homology and differ only in the length of the amino acid chain. One method to study this problem is to produce recombinant proteins from Alternaria. To explore these possibilities, the following experiments were performed. A strain of Alternaria was grown on minimum salts and glucose in a fermentation container with constant stirring and aeration. Rapidly expanding mycelia were removed from the culture and mRNA was extracted. Purified mRNA was reacted with reverse transcriptase and an aliquot of first copy single strand DNA was enriched for the presence of DNA coding for an Alternaria allergen by PCR amplification. Modified DNA was then spliced into lambda gt11 phage and yielded a recombinant library with 10(5) PFU. The library was screened for the presence of allergenic proteins using IgE containing human sera from Alternaria-sensitive patients. Positive plaques were cloned. PCR analysis of positive clones using an oligonucleotide from the reported N-terminal sequence of Alt a1 indicated an insert of 295 base pairs. Sequence analysis yielded a reading frame containing 84 amino acid and confirmed that this segment contained the code for the reported N-terminal amino acid sequence of Alt a1. A computer search for this sequence found no homologous proteins in the Entrez sequences. Northern blotting studies on RNA purified from nine strains of Alternaria with the radiolabeled 247 BP DNA fragment indicated that this sequence was present in all strains. The 247 BP nucleotide was spliced into the Pflag vector and clones containing insert in the proper reading frame were identified. The presence of recombinant protein in the clones was verified by SDSPAGE time studies. Protein produced in time studies was shown by immunoblotting and sandwich EIA to bind human IgE from Alternaria sensitive patients. This recombinant protein, containing amino acid sequence for Alt a1, is bound by human IgE and therefore should be useful as a model for studying allergy to the native Alternaria glycoprotein. Further research should define where this sequence occurs in the Alternaria genome and should determine the sequence of the entire protein.

How should zoster trials be conducted?

In 1994, an international group of interested clinicians and biostatisticians met to discuss the design of clinical trials in herpes zoster. They agreed that trials in herpes zoster should have prospectively agreed definitions of all outcome measures and plans for data analysis. In immunocompetent individuals, in whom pain is the major outcome measure, trials should only include patients over the age of 50 years, and for those recruited within 72 h of rash onset, should be designed to demonstrate superiority of any new therapy over existing antivirals. The primary endpoint should be time to cessation of pain for at least 4 weeks and, for the purposes of statistical analysis of its duration, the pain associated with herpes zoster ought to be considered as a continuum. All other variables, including the incidence of post-herpetic neuralgia and effects upon quality of life should be considered as secondary end-points. Evaluation of treatment effects on primary endpoints should be based upon an intent-to-treat (ITT) analysis and subgroup analysis should be used only to support the findings of the ITT analysis. These elements of good study design should be borne in mind in the evaluation of current and future trails of antiviral drugs in herpes zoster.

C-reactive protein in acute pulmonary exacerbations of patients with cystic fibrosis

C-reactive protein (CRP) concentrations were evaluated in 9 cystic fibrosis (CF) patients with acute pulmonary exacerbations and 14 patients with acute exacerbations of asthma without any symptoms of an acute infection. CRP concentrations were serially evaluated over the course of therapy in CF patients and compared with pulmonary function tests (PFTs) and clinical scores. CF patients were treated with aerosolized bronchodilators, intravenous fluids, and chest physiotherapy for 48 hours. Intravenous antibiotic therapy was added after 48 hours. Initial CRP concentrations differed significantly between patients with CF and those with asthma. CRP concentrations were elevated in 7 of 9 CF patients versus 3 of 14 asthma patients (P < 0.02). In CF patients, CRP concentrations did not correlate with PFTs (except on day 0) or clinical scores. Frequently PFTs and clinical scores continued to improve after CRP levels had reached their lowest concentrations. CRP concentrations decreased only after the addition of antibiotic therapy.

Premedication reduces the incidence of systemic reactions during inhalant rush immunotherapy with mixtures of allergenic extracts

BACKGROUND

Rush immunotherapy, while having many potential benefits, is associated with an increased incidence of systemic reactions.

OBJECTIVE

To determine whether pretreatment with medications reduces the rate of systemic reactions during rush immunotherapy and to identify predictors of such reactions if possible.

METHODS

We conducted a double-blind, placebo-controlled study of 22 allergic children ages 6 to 18 years who received rush immunotherapy. Active treatment consisted of a combination of H1 and H2 histamine antagonists and a corticosteroid in gelatin capsules given prior to administration of rush immunotherapy whereas placebo patients received lactose. Rush immunotherapy consisted of eight injections of increasing doses of a mixture of allergens to which each patient was skin-reactive over 1 1/2 days. Serial skin tests and peak expiratory flow rate measurements were performed during the procedure. Following the initial series of injections, patients were followed for 8 weeks and had blood drawn at 2-week intervals for measurements of specific IgG and IgE.

RESULTS

Systemic reactions were observed in 3 (27%) active and 8 (73%) placebo patients (Fisher's exact test: P = .047). The mean time for systemic reactions was 63 minutes after a previous injection. The most common dose causing a systemic reaction was 0.3 mL of 1:1000 (wt/vol). The best predictors of development of a systemic reaction were degrees of skin sensitivity to the extract before and after premedication. Local reactions were not associated with subsequent systemic reactions. Specific IgG rose by 2 weeks while specific IgE did not change significantly during the 8-week follow-up period. Pretreatment did not change the number of systemic reactions seen with subsequent injections.

CONCLUSIONS

Premedication significantly reduces the incidence of systemic reactions during rush immunotherapy and is therefore recommended. Degree of skin sensitivity to the injected extract may eventually prove to be a clinically useful predictor for the development of systemic reactions.

[Neuroleptic malignant syndrome in elderly hospital patients]

Neuroleptic malignant syndrome (NMS) has gained increasing attention over the past decade. Diagnostic features include exposure to major tranquilizers, acute onset of high fever, extrapyramidal symptoms and markedly elevated CPK. Other common signs include changes in mental status, tachycardia and leukocytosis. It usually runs its course within 10 days. Greater awareness and improved treatment have resulted in markedly decreased mortality. However, failure to diagnose and treat properly results in a significant risk of death. Most cases of NMS reported have been in those with psychiatric illness. Few cases have been reported in elderly patients without a psychiatric history. We describe an 85-year-old man, without previous psychiatric illness, who developed NMS while hospitalized on a general medical ward.

Injury type, injury severity, and repeat occurrence of alcohol-related trauma in adolescents

Injury associated with alcohol use is a significant problem among adolescents; however, routine evaluation of alcohol use in this population is not conducted. The purpose of this study was to compare injured adolescents presenting to an emergency room with a positive serum alcohol concentration (SAC+) with those injured adolescents with a negative serum alcohol concentration (SAC-). Data were collected retrospectively on 176 injured patients, between the ages of 13 and 18, consecutively admitted to a university hospital from January 1, 1989-December 31, 1990. Information collected included mechanism and severity of injury, outcome, SAC, length of stay, psychiatric history, prior or subsequent admission for injury, and hospital charges. Of those tested with an SAC, more than one-third had a positive SAC. Patients with positive SACs had a greater probability of having a psychiatric history and more frequently had a prior or subsequent injury. Furthermore, only 34% of SAC+ patients were referred for counseling. The results indicate that a SAC should be obtained on all adolescents admitted for trauma, that adolescents presenting with injuries and a positive SAC should be referred for alcohol and psychiatric assessment, and that injured adolescents may be at increased risk for repeat injuries in the future.

A double monoclonal antibody assay for the Alternaria allergen GP70

A double monoclonal antibody-based assay for the 70-kD Alternaria allergen GP70 is described. The assay is sensitive to GP70 concentrations as low as 0.2 microgram/mL and is highly specific for this allergen. The glycoprotein detected by this assay is shown to bind to human IgE from Alternaria-sensitive patients, proving that it is an allergen. Two of three commercial Alternaria preparations tested contained no detectable GP70. Several related fungi were shown to contain detectable concentrations of GP70, but the most abundant source was a commercial preparation of house dust. Further measurement of GP70 in biologic materials should increase our knowledge of the distribution and importance of this Alternaria allergen in the environment and in the development of allergic diseases.

Enhanced sensitivity of immunoblotting with peroxidase-conjugated antibodies using an adsorbed substrate method

Immunoblots probed with immunoglobulin E (IgE)-containing sera from allergic patients are frequently used in allergy research. Current techniques for detection of specific IgE include radiolabeled and enzyme-linked methods. Although radiolabeled methods are very sensitive, many research groups prefer non-radioactive procedures with equal or greater sensitivity. Alkaline phosphatase (AP) and horse radish peroxidase (HRP) are the most frequently used conjugating enzymes for immunoblotting with the former generally recognized as more sensitive. We describe a method of immunoblot detection using HRP-conjugated immunochemicals with sensitivity equal to and for some systems greater than that of AP conjugates. An adsorbed substrate method for developing immunoblots probed with HRP immunochemical conjugates is compared with traditional AP and HRP methods. The adsorbed substrate system, when used to detect IgE binding to allergic proteins, gives high resolution and delineates bands not otherwise seen. The system has advantages of high sensitivity, rapid development and conservation of immunochemicals. Problems of fading, sensitivity to heat and light, and high background can be solved with increased washing, prompt photography and computer scanning.

The effect of time and extraction buffers on residual protein and allergen content of extracts derived from four strains of Alternaria

BACKGROUND

A series of studies was performed to identify optimal elution conditions for production of desired Alternaria allergens with simultaneous reduction of undesired ones.

METHODS

Proteins and allergens from four strains of Alternaria extracted for differing time intervals and in different buffers were analyzed by one- and two-dimensional electrophoresis, as well as by immunoglobulin E enzyme-linked immunosorbent assay inhibition and immunoblotting.

RESULTS

The amount of protein and carbohydrate released varied with each time interval but was consistent between buffers. Extracts from longer time intervals tended to contain more carbohydrate. Electrophoresis of the four strains demonstrated many similar proteins; however, the concentrations of these proteins showed considerable interstrain difference. Comparison of extraction times for single strains by immunoblotting showed that certain allergens are preferentially released during specific time intervals. Some allergens were seen to be most prevalent in a 24-hour extract, whereas others were most prevalent in a 1-hour extract. Two-dimensional electrophoresis resolved bands into discrete spots. The major shared elements of the four strains could be easily identified. The appearance and disappearance of individual protein elements with time was seen.

CONCLUSIONS

Elution conditions have a significant impact on quantities of specific glycoproteins contained in extracts of Alternaria and must be controlled and optimized when such extracts are produced for allergen purification.

Selection of representative Alternaria strain groups on the basis of morphology, enzyme profile, and allergen content

In an attempt to identify representative strains, 12 strains of Alternaria alternata were contributed by four different research groups. Each was grown on two types of solid media and characterized with descriptions of pigmentation and morphology. Enzyme profiles were determined on both the cellular antigen and the culture filtrate material with use of a commercial kit. Concentrations of a previously described Alt a 1 and a 70 kd allergen, GP70, were measured by a two-antibody "sandwich" ELISA. Allergenic proteins were visualized by IgE immunoblots. With use of these criteria, four separate strains were identified that might serve as representative of Alternaria for further research.

Chest pain in otherwise healthy children and adolescents is frequently caused by exercise-induced asthma

Chest pain in children and adolescents, unlike in adults, is rarely of cardiac origin and its etiology is frequently unknown. In this age group, chest pain can limit normal activity and sports participation. The reported incidence of exercise-induced asthma in children with chest pain is less than 20%. For this study, 88 otherwise healthy children and adolescents with chest pain followed a treadmill protocol without a warm-up period designed to obtain a target heart rate of 180 or greater during the first several minutes of exercise. Patients maintained this workload for 6 to 8 minutes. Pulmonary function tests performed prior to exercise and at 2, 5, 10, 15, 20, and 25 minutes revealed a decrease in forced expiratory volume in 1 second or peak expiratory flow rate of greater than or equal to 15% in 64 (72.7%) children. Inhaled albuterol resulted in subjective improvement in 97% (35/36) and objective improvement in 70% (25/36) of patients. In otherwise healthy children and adolescents with chest pain, the incidence of exercise-induced asthma seems greater than previously reported. Treatment with bronchodilators may help these patients lead a more active life-style.

Continuous nebulization for status asthmaticus

Continuous nebulization of beta 2 agonists is now recognized as a useful treatment for severe exacerbations of asthma. This mode of administration has been described both for adults and children in the emergency room and in the intensive care unit. It has been suggested that early use of continuous inhalation therapy may reduce or prevent the need for intensive care unit admissions and potentially toxic treatments such as intravenous beta agonists and mechanical ventilation. A number of methods have been proposed for continuous administration of beta agonists, however, there is no concensus as to the best one. The lack of controlled studies clearly demonstrating superior outcomes in patients who receive this treatment leaves many questions unanswered. In addition, differences in efficacy and safety between frequent and continuous nebulization, if any, are unclear. Adverse effects primarily consist of muscle cramps, hypokalemia, and hyperglycemia. It is suggested that use of this treatment should be considered for the asthmatic patient who demonstrates progression towards significant obstruction before institution of the more toxic treatments listed above. While continuous nebulization has not been proven to prevent the need for them, it is clearly safer. Should population studies eventually fail to demonstrate its superior efficacy, continuously nebulized beta 2 agonist therapy may still be beneficial for individual patients.