Mouse IgE Test Research Articles

Assessment of Airway Sensitization Potential of Inhaled Trimellitic Anhydride by Monitoring the Elicitation Phase in a Mouse Model

While several skin sensitization tests have been developed and are available as regulatory toxicity tests at present, no such tests for the airway have been established. We have been developing an animal model by introducing an elicitation phase into the mouse IgE test (MIGET) for assessment of agricultural chemicals with airway sensitization potential. In the current study, trimellitic anhydride (TMA), a representative low molecular weight (LMW) airway sensitizer, was examined for its sensitization potential in our mouse model. Mice were epicutaneously sensitized to TMA on Days 0 and 7, followed by an inhalation challenge with TMA dust at high or low concentration on Day 14. Groups of different sensitization route including inhalation were established for comparison of effectiveness of immunization. Non-sensitized animals challenged with TMA dust served as controls. An ovalbumin-sensitized and -challenged animals constituted a reference group (OVA). Enhanced pause (Penh) was measured as an indicator of airflow disturbance by using a restrained flow whole body plethysmograph. The high TMA concentration group exhibited an augmented Penh, elevated IgE values, and pronounced influx of eosinophils into their BAL fluid and minor infiltration of inflammatory cells including eosinophils into the lung. The low TMA concentration group also exhibited elevated IgE values and a less frequent occurrence of minor lung inflammation, but these were not accompanied by any positive responses in Penh and BAL fluid. Almost all mice in the other immunization route groups exhibited negative responses for any parameter examined. The OVA group showed no changes in breathing pattern during the inhalation challenge despite presenting a high total serum IgE value. These results suggest that this mouse model may be useful for assessment of airway sensitization potential of agrochemicals, but by way of epicutaneous sensitization.

Sensitization potential of gold sodium thiosulfate in mice and guinea pigs

Since gold sodium thiosulfate (GST) has been included in a standard patch test series for diagnosis of allergic contact dermatitis from gold, the incidence of patients showing positive reactions to gold is increasing. However, there were little reports on induction of gold sensitization in animals. In this study, we have examined the sensitization potential of GST using mice and guinea pigs. In the guinea pig maximization test, 2 or 6 out of 10 animals showed positive skin responses, mainly edema, by challenge with 2% or 5% GST in 50% ethanol solution, respectively. In the mouse ear swelling test, positive ear swelling (20% greater increase in ear thickness) after challenge with GST was shown in 2 out of 6 mice those previously treated with GST. Topical exposure of mice to GST in 70% dimethylsulfoxide solution induced small increases in the lymph node weight and the lymph node cell (LNC) number in the murine local lymph node assay (LLNA). A greater degree of LNC responses were observed in the sensitive mouse lymph node assay (SLNA) compared with the LLNA, but the stimulation index of total lymph node response by GST was not so high. From these results, GST was identified as a contact allergen, but the sensitization potential was not so strong. In the mouse IgE test, treatment of mice with GST resulted in a statistically significant increase in the serum IgE antibody concentration that associated with immediate-type hypersensitivity reaction. It may suggest that the sensitization responses from gold would appear not only at the contact site but also systematically.

Equal Allergenic Potency of Beta-Lactam Antibiotics Produced by Chemical or Enzymatic Manufacturing – Mouse IgE Test

Background: Cephalexin and amoxicillin are semisynthetic β-lactam antibiotics with a broad spectrum of antibacterial activity against gram-positive and gram-negative microorganisms. Both antibiotics are produced by a new ‘green’ process in which enzyme technology is used to combine the intermediate structure and the side chain in an aqueous medium to yield cephalexin or amoxicillin, thus avoiding the use of several chemical reagents and volatile organic solvents. As a result of the enzyme technology a new residual protein impurity has been identified. To check for the sensitizing capacity of the residual protein, a mouse IgE test was used to detect differences in the production of specific IgE by chemical or enzymatic preparations of the antibiotics. Methods: Balb/c female mice were immunized intraperitoneally with alum and conjugates of different amoxicillins or cephalexins with ovalbumin (OVA). After 16 days, the amoxicillin mice were injected with one half the original amount of antigen. After 19–23 days, the sera were tested for specific IgE by the passive cutaneous anaphylaxis assay in Sprague-Dawley rats. The greatest dilution of sera which resulted in a positive response was the titer of specific IgE. Results: No significant differences were found between the titers of specific IgE caused by the chemically and enzymatically produced β-lactam antibiotics, indicating that the antibiotics are equal in allergenicity. Conclusions: The data show that a residual level of 35 ppm protein did not affect the allergenic potency of these β-lactam antibiotics as determined by the mouse allergenicity model.

THE MOUSE IgE TEST: INTERLABORATORY EVALUATION AND COMPARISON OF BALB/c AND C57BL/6 STRAIN MICE

The mouse IgE test is a novel method for the prospective identification of chemicals that have the potential to cause allergic sensitization of the respiratory tract. Activity is measured as a function of increases in the concentration of total serum IgE induced by topical exposure of mice to chemicals; those chemicals that elicit a substantial elevation in IgE are classified as respiratory allergens. The present investigations were designed to evaluate further the utility of the mouse IgE test. For this purpose theassay was conducted in each of fiveindependent laboratories using trimellitic anhydride (TMA), a known cause of respiratory sensitization and occupational asthma, and 2,4-dinitrochlorobenzene (DNCB), a potent contact allergen that is considered not to cause sensitization of the respiratory tract. For these investigations BALB/c mice were used, which are currently the strain of choice for the mouse IgE test. In four of five laboratories, exposure of mice to TMA caused a statistically significant...

Evaluation of the sensitizing potential of eugenol and isoeugenol in mice and guinea pigs.

The sensitizing properties of the fragrances eugenol and isoeugenol have been investigated experimentally. The potential of these materials to induce sensitization of the respiratory tract was examined using the mouse IgE test, a novel but as yet unvalidated method for the predictive identification of chemical respiratory allergens. Comparisons were made with the activity of eugenol and isoeugenol in two predictive tests for contact sensitization potential: the murine local lymph node assay and the guinea pig maximization test. Both chemicals elicited positive responses in these tests, isoeugenol exhibiting a greater potential for contact sensitization than eugenol. Isoeugenol was negative at all concentrations examined in the mouse IgE test. In the same assay, exposure to eugenol was associated with a statistically significant increase in serum IgE concentrations when initial application concentrations of 2.5% were used. However, at higher test concentrations eugenol was negative in the mouse IgE test. It is concluded that neither eugenol nor isoeugenol have a significant potential to cause sensitization of the respiratory tract, a conclusion that is apparently consistent with the lack of evidence for occupational respiratory allergy associated with exposure to these chemicals. The evidence for isoeugenol lacking respiratory sensitization activity is particularly strong and it is proposed that this chemical may be of value as a negative control in the development and validation of new predictive test methods for the identification of chemical respiratory allergens.

Predictive testing for respiratory sensitization in the mouse

Attempts to develop predictive test methods for the identification of chemical respiratory allergens have to date focused almost exclusively on the guinea pig. In recent years there has, however, been a growing interest in the mouse as a model for examination of sensitization potential. In this article two alternative approaches to the lexicological investigation of respiratory sensitization are described. Both are based on an understanding of the nature of immune responses induced in mice by chemical allergens. The mouse IgE test seeks to identify chemicals capable of causing allergic sensitization of the respiratory tract as a function of induced increases in the serum concentration of IgE. The second approach, cytokine fingerprinting, makes use of the observation that chemical allergens of different types provoke in mice qualitatively divergent immune responses characterized by discrete cytokine secretion profiles.

Identification of Chemical Respiratory Allergens: Dose-Response Relationships in the Mouse IgE Test

A mouse IgE test for the prospective identification of chemical respiratory allergens has been proposed previously. In this method, respiratory sensitizing potential is measured as a function of induced changes in the serum concentration of IgE following topical exposure of mice to the test material. In previous studies, changes in serum IgE were measured after treatment of mice with only a single concentration of chemical. The purpose of the investigations reported here was to examine dose-response relationships in the mouse IgE test with both chemical respiratory allergens and chemicals considered not to cause pulmonary hypersensitivity. The respiratory sensitizers examined were toluene diisocyanate (TDI), di-phenylmethane-4,4′-diisocyanate (MDI), hexamethylene diisocyanate (HDI), and trimellitic anhydride (TMA), all of which are known to cause occupational respiratory allergy in a proportion of exposed individuals. Results were compared with those obtained with 2,4-dinitrochlorobenzene (DNCB) and oxazolone, two contact allergens known or suspected not to cause sensitization of the respiratory tract. In each case, induced changes in serum IgE were measured under conditions of exposure, with respect to application concentrations, where all chemicals elicited positive responses in the local lymph node assay provoking lymphocyte hyperplasia in lymph nodes draining the site of treatment. In the mouse IgE test, exposure to TDI, MDI, HDI, and TMA in each instance caused a substantial dose-related increase in the serum concentration of IgE measured 14 days following the initiation of treatment. In contrast, exposure of mice to the contact allergens DNCB and oxazolone resulted in either no change in serum IgE levels (DNCB) or only a comparatively modest increase (oxazolone). These data confirm that chemical contact and respiratory allergens differ markedly with respect to the quality of immune response induced in mice and their ability to stimulate changes in the serum concentration of IgE. It is proposed that the mouse IgE test may provide a useful alternative approach to the prospective identification of chemicals that have the ability to cause sensitization of the respiratory tract.

Serological responses induced in mice by immunogenic proteins and by protein respiratory allergens

It is known that a variety of materials, including both low molecular weight chemicals and proteins, is able to induce occupational respiratory allergy. We have shown previously that exposure of mice to chemical respiratory sehsitizers results in both a marked increase in the serum concentration of IgE and the appearance of specific IgE antibody. In the present study we have examined the characteristics of immune responses induced in mice following intraperitoneal exposure to 3 protein respiratory allergens, ovalbumin (OVA), a lipase from Aspergillus oryzae (LP) and an amylase from Bacillus subtilis (AM) and to a fourth protein, bovine serum albumin (BSA), which is considered usually not to cause respiratory sensitization. Under conditions where all proteins provoked IgG antibody responses, only OVA, LP and AM elicited specific IgE antibody. As judged by passive cutaneous anaphylaxis (PCA) assay, BSA failed to induce an IgE response. In contrast to chemical respiratory sensitizers, the protein allergens examined here failed to cause a substantial increase in the serum concentration of IgE; OVA and AM induced no increase in serum IgE and LP only a comparatively modest increase relative to control values. In conclusion, these data demonstrate that while protein respiratory allergens are able to provoke specific IgE antibody, they fail to cause a marked increase in the concentration of this immunoglobulin in the sera of treated mice. It would appear, therefore, that the mouse IgE test, which seeks to evaluate chemical respiratory sensitization potential as a function of induced changes in the concentration of serum IgE, will be inappropriate for the identification of protein respiratory allergens. Nevertheless, identification of protein allergens may be possible by exploiting the observations reported here that such proteins induce in mice specific IgE antibody responses.

The identification of chemicals with sensitizing or immunosuppressive properties in routine toxicology

In the context of this paper, immunotoxicity is taken to encompass immunosuppression/immunopotentiation and allergy. Over the last 10 to 15 years, well characterized methods for the assessment of altered immune competence have been reported. This has led to proposals for tiered testing schemes. This review examines the suitability of immunotoxicity parameters for inclusion in routine 28-day studies and comments on methods that have been proposed for incorporation within the guidelines issued by the US FDA and US EPA and OECD. It is recommended that the existing OECD Guideline 407 is modified to incorporate total and differential blood cell counts, spleen and thymus weight and histopathology, and draining and distal lymph node histopathology for Tier I level testing. Data so generated will provide a reliable and accurate means of identifying at an early stage potential immunotoxic effects. Tier II testing should be carried out on a case by case basis and only assuming positive results are obtained at Tier I. An increasingly sophisticated understanding of the nature of immune responses to chemical allergens has facilitated the design of novel predictive methods for the identification of sensitizing activity. Opportunities which arise from these new developments in allergy testing such as the local lymph node assay, mouse ear swelling test, and the mouse IgE test should be monitored closely.