Radioallergosorbent Test RAST

This test was developed by Wide et al. (1967) and later extended to the determination of IgE antibodies to penicillin. The principle is rather simple. The antigen is coupled to particles such as Sephadex or paper disks which are allowed to react with the test serum. Specific antibodies will bind the antigen and the complex formed can be detected by adding a radiolabeled anti-IgE. 

In type I hypersensitivity reactions, the penicillin RAST has been used by several authors to estimate the specific IgE response (Assem 1972 Wide and Juhlin 1971). Using a modification of the classical RAST which improves the sensivity of the tests, Adkinson (1975) found an excellent correlation between the positive clinical history, skin tests with PPL, and the results of the RAST. 

These results contain, among other data, some surprising figures  

The frequent positive nature of cell-mediated reactions in type I reactions These observations decrease to some extent the value of tests specific for type I- 

IV reactions as clinical correlates. Nevertheless, the penicillin RAST offers a reliable and safe way to explore at least type I allergic reactions. An extension of that procedure to other drugs commonly responsible for allergic reactions is therefore highly desirable. 

---

Other studies have indicated respiratory effects from chronic exposure to HDL The radioallergosorbent test (RAST) method and skin tests were used to evaluate the significance of type I sensitization, its incidence, and relationship to respiratory dysfunctions in a large population of isocyanate-exposed workers. A group of 621 workers engaged in isocyanate processing for a period of 2 weeks to 40 years were studied. Sex of the workers was not reported. Of these workers, 183 had contact with TDI ... 

Treatment with omalizumab, the monoclonal humanized anti-IgE antibody, is reserved for patients with chronic severe asthma inadequately controlled by high-dose inhaled corticosteroid plus long-acting B-agonist combination treatment (eg, fluticasone 500 meg plus salmeterol 50 meg inhaled twice daily). This treatment reduces lymphocytic, eosinophilic bronchial inflammation and effectively reduces the frequency and severity of exacerbations. It is reserved for patients with demonstrated IgE-mediated sensitivity (by positive skin test or radioallergosorbent test [RAST] to common allergens) and an IgE level within a range that can be reduced sufficiently by twice-weekly subcutaneous injections. 

The radioallergosorbent test (RAST) is a solid-phase sandwich RIA and does not suffer from these general disadvantages that is, it is a direct assay, eliminates nonspecific serum effects, and measures biologically active allergen-specific IgE sandwiched between allergen and Fc-specific anti-IgE antibodies. 

Radioallergosorbent tests (RAST) which detect IgE antibodies to specific muscle relaxants have been developed (65,66) and are commercially available for some anesthetic drugs (64,71). However, the sensitivity of IgE testing is variable and reached 90-97% in selected specialized centers only (72). 

In clinical diagnosis of sensitivity to allergens in food, the two methods used most frequently are the skin prick test (SPT) and the radioallergosorbent test (RAST). These tests have been used reliably for the diagnosis of allergy to peas, codfish, peanuts, egg white, wheat and wheat flour but were only partly reliable in detecting allergy to cow s milk, sardines, and white bea ns ( ). 

Until recently the detection of lupine protein was based on the use of serum from lupin-allergic patients and performed by immunoblot and radioallergosorbent test (RAST) analyses (Figure 22.10). The standardization of serum is difficult, and limited availability makes such methods unsuitable for routine analysis. Recently, a sandwich... 

There are no reports in the literature regarding radioallergosorbent tests (RAST) in IgE-mediated tetracycline allergies. Precipitating antibodies have been... 

Immunologic-type agents are confirmed by specific positive radioallergosorbent tests (RASTs) and by negative tests on control subjects, rarely by passive transfer tests (Prausnitz-Kiistner tests) in animals. In vitro tests can also be used to assess the relationship with a possible IgE-mediated mechanism, namely, determination of histamine release from peripheral basophils or platelet cytotoxicity test, which explores the presence on platelets of specific IgE antibodies bound to the low-affinity receptor for IgE. 

Tyrophagus putrescentiae (ALK, Copenhagen, Denmark). It seems evident that if prick tests or alternatively radioallergosorbent tests (RASTs) to storage mites are not performed, it is not possible to investigate storage mites as a possible cause of contact urticaria. 

Investigations should also include tests to detect type-I allergy to polymeric glove materials and glove powders (prick tests, determinations of latex-specific IgE antibodies in serum, e.g., radioallergosorbent test (RAST), and challenges with suspected gloves). See also Chap. 88, by Turjanmaa. 

Schirmer et al. (1987) described one baker with dermatitis. He had positive skin-prick tests to a-amylase and various bread improvers. The immediate test reaction to a-amylase persisted for 48 h. A patch test with a-amylase was also positive, as well as radioallergosorbent test (RAST) to a-amylase, malt and bread improvers. We had a patient with occupational allergic contact urticaria from fungal but not bacterial a-amylase (Kanerva et al. 1997). Accordingly, enzymes with the same function and the same name may have different antigenic characteristics. When reporting about enzyme allergy, it is important to reveal details of the causative enzymes. 

---