Latex allergosorbent test (LAST): a new immunoassay for specific IgE with latex particles

Latex allergy

Coined the next major health concern of the decade, allergy to natural rubber latex affects people routinely exposed to rubber products. Groups at highest risk include health care workers, rubber industry workers, and persons who have undergone multiple surgical procedures, especially those with spina bifida. Allergy to latex is a type I, immediate, IgE-mediated reaction, which can lead to anaphylaxis and death. Much of latex research is published in allergy journals. Dermatologists may not be aware of the prevalence, symptoms, risks, diagnosis, and treatment of latex allergy. These topics are the subject of this review. Research concerning antigenic proteins, as well as sources of latex alternatives, is also summarized. (J Am Acad Dermatol 1998;39:1-24.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should have a clear understanding of the history, biology, epidemiology, mechanism, clinical characteristics, diagnostic work-up, and treatment of latex allergy. Readers should also have a greater understanding of multiple potential allergenic latex proteins and their importance in preventing future latex-sensitization.

Allergen-antibody complexes can efficiently prevent seasonal rhinitis and asthma in grass pollen hypersensitive patients. Allergen-antibody complex immunotherapy

We have prepared antigen-antibody complexes from grass pollen allergens and autologous specific antibodies isolated by immunoadsorption from the serum of allergic patients. These complexes were inoculated into patients in a double-blind trial to evaluate their effect on grass pollen-related rhinitis and bronchial asthma. Thirty-eight grass pollen-hypersensitive patients were allocated to three groups; patients in the first two groups were treated with antigen-antibody complexes at different ratios and dosages and were compared with the third group who received the placebo carrier buffer alone. In addition, we treated a fourth group who had already received antigen-antibody complex inoculation during the previous pollen season. Injections were given every 2 weeks during the pollen season, starting 5 weeks prior to it. Tolerance was excellent with no signs of local or systemic side effects. The treatment prevented nasal symptoms while enabling the patients to reduce antihistamine intake. Bronchial asthma was virtually absent in the treated groups even though no bronchodilators or corticosteroids had to be taken. Specific IgE antibodies did not increase during the pollen season nor did IgG "blocking" antibodies. Inoculation of allergen-antibody complexes could provide a valuable alternative for the treatment of immediate hypersensitivity to airborne allergens as it appears to be safe and rapidly efficacious. This treatment offers several advantages compared to conventional hyposensitization and is characterized by the absence of an increase in specific IgG antibodies.

Clinical evaluation of a new in-vitro assay for specific IgE, the immuno CAP system

The Pharmacia CAP system is a new assay for specific IgE characterized by a new solid phase (hydrophilic polymer encased in a capsule). The CAP results were compared to those of the Phadebas IgE RAST and skin-prick tests (SPT) performed in 145 subjects suffering from rhinitis and/or asthma with eight common inhalant allergens (total number of tests = 1160). Concording CAP/RAST results were found in 91% of the tests. The CAP was positive in 78% and the RAST in 65% of the positive SPT. Conversely, the CAP was negative in 90.6% and the RAST in 96.4% of the negative SPT. A pattern negative SPT, negative RAST and positive CAP' was found in 56 tests (40 subjects): in four such subjects, the CAP positivity was confirmed by a positive IgE crossed radioimmunoelectrophoresis. Three borderline positive results were found among 240 negative controls (serum from cord blood or non-atopics). These data indicate that compared with SPT the CAP system is (a) more sensitive than the Pharmacia RAST and (b) does not seem less specific.

Complexes of grass pollen allergens and specific antibodies reduce allergic symptoms and inhibit the seasonal increase of IgE antibody

Complexes made from antigen and specific antibodies have been used to suppress specific antibody production. This property is of potential therapeutic interest in immediate hypersensitivity states which are characterized by hyperproduction of IgE antibodies. We report here on the use of antigen-antibody complexes in patients with hypersensitivity to grass pollen. Specific anti-allergen antibodies were prepared by immunoadsorption from the serum of hypersensitive individuals and mixed with grass pollen allergens to form complexes in antibody excess. These complexes were used in a strictly autologous manner for inoculating patients prior to and during a pollen season. The study comprised two randomly defined groups of 15 patients who were inoculated intradermally either with a preparation of allergen-antibody complexes or with the carrier buffer, according to a double-blind protocol. Diary cards were used to follow nasal and ocular symptoms, bronchial asthma and medication intake. Specific IgE antibodies were assayed during the trial and 1 year afterwards. Inoculation of allergen-autologous antibody complexes was well tolerated. It significantly reduced ocular symptoms (Mann-Whitney U-test, P less than 0.05), bronchial asthma during the first part of the season (Mann-Whitney U-test, P less than 0.001) and drug intake (Mann-Whitney U-test, P less than 0.001). This treatment prevented the seasonal increase in specific IgE antibodies, whose production continued to decrease after the pollen season. These effects were obtained within a few weeks of treatment, using a cumulative amount of allergen 100-fold lower than the amount which would have been used for a conventional hyposensitization.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergic bronchial asthma due to Dermatophagoides pteronyssinus hypersensitivity can be efficiently treated by inoculation of allergen-antibody complexes

Antigen-antibody complexes were made from allergens of the common house dust mite, Dermatophagoides pteronyssinus (Dpt) and an excess of purified autologous specific antibodies. These complexes have been used to treat Dpt-hypersensitive patients who suffered from chronic bronchial asthma. Clinical symptoms and medication intake were followed by filling in diary cards. Peak expiratory flow, measured four times a day, was also followed. Intradermal skin tests and bronchial challenge tests were performed with allergen together with an evaluation of nonspecific bronchial reactivity. Specific IgE and IgG antibodies were assayed after separation from the bulk of serum immunoglobulins by immunoadsorption. The study was carried out over two years according to a double-blind protocol. Intradermal inoculation of antigen-antibody complexes resulted in a marked reduction of both clinical and medication scores. No systemic side-effects were observed and only mild wheal and flare reactions were noted at the injection site. The treatment showed a drastic reduction of specific skin and bronchial reactivities with only marginal effects on nonspecific bronchial reactivity. Concentrations of specific IgE antibodies decreased significantly during the first weeks of treatment and remained at these lower values throughout the study. Specific IgG antibodies actually decreased in the majority of treated patients. The total amount of allergen used in this study was less than 1% of the amount currently used for conventional hyposensitization with the same allergen. These findings show that antigen-antibody complex inoculation is an efficient and safe means of treating allergic bronchial asthma and that the mechanism of action is likely to differ from conventional hyposensitization.