Vitro Allergy Tests

The leucocyte histamine release test (referred to in greater detail in Chaps. 1-7) is one of the in vitro correlates of immediate allergy which may find useful application in investigating reactions to local anaesthetics. It is of some value in detecting acute reactions, whether they are truly anaphylactic or due to direct (non-immune) histamine release (anaphylactoid). It is also more accurate (quantitative), more reliable and more predictive than skin tests, and above all it is free from risk. 

The first conclusion to be drawn from those results was that much needs to be done concerning the testing material, since the histamine release was well below that obtained with the conventional allergens, such as pollen and house dust mite extracts. Secondly, the negative results in two-thirds of the patients could either be due to the poor test allergens used, or that the clinical diagnosis blaming the local anaesthetic for these reactions was incorrect. 

As a follow-up of the latter point, four of the patients with negative leucocyte tests were re-admitted to hospital and re-exposed to the local anaesthetic (or anaesthetics) in question, under monitored observations, and taking adequate precautions. None of the four patients developed reactions under these circumstances. 

It is not totally inconceivable that in predisposed subjects, local anaesthetics may cause an anaphylactoid reaction via direct conversion of the third complement in the same way as may occur with certain anaesthetic induction agents (discussed elsewhere). 

It has been suggested the local anaesthetics might have the opposite effect, namely inhibition of histamine release (Mongar and Schild 1957). This effect, if true, would to a certain extent cancel out an anaphylactic response to the drug. One of the relevant observations was that in some leucocyte experiments we noticed that histamine release was significantly lower in the presence of certain local anaesthetics, e.g., prilocaine, than in their absence (Tyrode solution was used in all experiments). 

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Assem ESK, Vickers MR (1974) Tests for penicillin allergy in man. II. The immunological cross-reaction between penicillins and cephalosporins. Immunology 27 255 Assem ESK, Vickers MR (1975) Investigation of the response to some haptenic determinants in penicillin allergy by skin and in vitro allergy tests. Clin Allergy 5 43... 

In vitro Diagnosis. Unfortunately, there is no reliable in-vitro allergy diagnostic test available for routine use. Gall et al. [27] had used a self-made radioallergosorbent test with coupled LA to polystyrol discs, however, all the patients were negative. In-vitro cellular diagnostic assays have not been described as useful until now. 

In diagnosing drug allergies, the patient s history, skin testing, some in vitro laboratory tests, and the challenge test are the backbone of the investigative procedures. 

There is no meaningflil correlation between laboratory corrosion tests and clinical performance, but high in vitro corrosion rates on several high nickel dental prosthetic alloys (163), together with the prevalence of allergy to nickel caused by plated jewelry, gives cause for caution. 

Allergy mediated by selective IgE to certain types of NSAIDs by which symptoms are caused exclusively by a specific group of NSAIDs and no cross-reactivity exists with the other groups of anti-inflammatories. In a study carried out with 26 methimazole-allergic patients with IgE-mediated reactions [33], 14 of which developed anaphylaxis, BAT showed a sensitivity of 42% with an optimum specificity of 100%. No other validated in vitro test exists to date for the diagnosis of this disorder and so it represents an essential aid to diagnosis. 

Perform allergy diagnosis (after 3-4 weeks including in vitro diagnosis, skin test and if necessary provocation tests)... 

High-dose penicillin G traditionally has been the drug of choice for the treatment of pneumococcal meningitis. However, due to increases in pneumococcal resistance, the preferred empirical treatment now includes a third-generation cephalosporin in combination with vancomycin.13 All CSF isolates should be tested for penicillin and cephalosporin resistance by methods endorsed by the CLSI. Once in vitro sensitivity results are known, therapy may be tailored (Table 67-3). Patients with a history of type I penicillin allergy or cephalosporin allergy may be treated with vancomycin. Treatment should be continued for 10 to 14 days, after which no further maintenance therapy is required. Antimicrobial prophylaxis is not indicated for close contacts. 

Only a few in vivo dermal toxicity studies have been reported so far. Huczko and Lange [50] evaluated the potential of raw CNTs to induce skin irritation by conducting two routine dermatological tests (patch test on 40 volunteers with allergy susceptibilities and Draize rabbit eye test on four albino rabbits). Koyama etal. [51] showed the biological responses to four different types of carbon nanotubes (SWNTs, two types of MWNTs with different diameters, and cup-stacked carbon nanotubes) after their subcutaneous implantation in mice. Both tests [50, 51] showed no or poor irritation effects. However, the in vitro studies in epidermal cell lines exposed to CNTs, and also a more recent report on the toxic outcomes of topical exposure of mice to SWNTs [46], have raised concerns over these assessments. Clearly, this is an area requiring further scientific evaluation. 

Foods can be treated based on in vitro specific IgE level testing (such as Pharmacia Unicap) or challenge testing. Dosage depends on the severity of the food allergy. The more severe food allergies require smaller doses. Antigens are used 3 times daily until tolerance develops. Specific IgE levels are rechecked typically every 6-12 months. Doses are not increased until specific IgE levels start to decline. 

It has also been reported that patients with allergic-like events after penicillin treatment have had a markedly risk of events after subsequent cephalosporin antibiotics. Cross-reactivity is not an adequate explanation for this increased risk and the data obtained indicate that cephalosporins can be considered for patients with penicillin allergy <2006MI354.ell>. Comparisons of parenteral broad-spectrum cephalosporins have been tested against bacteria isolated from pediatric patients. The results have indicated that cefepime has been the most broad-spectrum cephalosporin analyzed and it is a very potent alternative for the treatment of contemporary pediatric infections in North America <2007MI109>. The historical safety of the most commonly used oral cephalosporins has been reviewed <2007MIS67>. The antimicrobial spectrum and in vitro potency of the most frequently prescribed orally administered cephalosporins (cefaclor, cefdinir, cefpodoxime, cefprozil, cefuroxime axetil and cephalexin has also been reviewed <2007MIS5>. 

Test on cellular immunity in vitro assays for lymphocyte and eosinophil activation it is performed for distinguishing between children with and without food allergy, based on determination of Th2 type cytokines (11-4), as compared to nonallergic children producing predominately Thl cytokines (interferon-y) (Nowak-Wegrzyn, 2003). 

R. Kwiecien, B. Maderegger, and K. Hoffmann-Sommergruber. 2005. In vitro analysis of birch-pollen-associated food allergy by use of recombinant allergens in the basophil activation test. Int Arch Allergy Immunol 136 (3) 230-238. 

Immunosuppression can cause a reduction of the animal s resistance to infection and, under certain conditions, also to an increased susceptibility to tumorigenesis (tumor-promotion). In contrast, hyperactivity of the immune system can result in autoimmune diseases or increase the sensitivity to allergies. While it is difficult to identify the mechanisms of the effect(s) of immuno-toxicity it is relatively easy to detect such properties. Information can be provided by investigating special parameters from the rat used in short-term or sub chronic rodent studies (type I tests) (FDA/FDCA 1993). The other category of tests uses in vitro techniques (type II tests). 

Specific immunotherapy is defined as the administration of increasing doses of an allergen extract to an allergic patient suffering from IgE-mediated hypersensitivity. As a prerequisite the allergy has to be determined by an SPT or an in vitro test like the RAST. Several questions arise in connection with immunotherapy of mold allergy ... 

Which in vivo or in vitro tests yield the most reliable results in the diagnosis of fungal allergy ... 

Van der Zee JS, de Groot H, van Swieten P, Jansen HM, Aalberse RC Discrepancies between the skin test and IgE antibody assays Study of histamine release, complement activation in vitro, and occurrence of allergen specific IgE. J Allergy Clin Immunol 1988 82 270-281. 

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