Skin test-positive immediate hypersensitivity reaction to iodinated contrast media: the role of controlled challenge testing.

BACKGROUND: Immediate hypersensitivity reactions (IHR) to iodinated contrast media (ICM) have traditionally been considered nonallergic; however, the increasingly frequent reporting of positive skin test and basophil activation test results suggests a specific allergic mechanism in some patients. Skin tests have been proposed as a useful tool for diagnosis, although their sensitivity and predictive values remain to be determined. The role of controlled challenge testing has not been assessed. OBJECTIVE: We aimed to evaluate the role of controlled challenge testing in skin test-positive IHR to ICM. PATIENTS AND METHODS: We evaluated 106 patients with IHR to ICM by performing skin tests with the agent that caused the reaction. Patients with a positive result were selected. Skin tests were extended to a series of 8 ICMs; 5 patients underwent controlled challenge test with an alternative skin test-negative ICM; a further 2 patients underwent computed tomography with an alternative skin test-negative ICM. No premedication was administered. RESULTS: Intradermal test results were positive to the ICM that caused the reaction in 11 out of 106 patients (10.4%). Five of the 11 patients tolerated a controlled challenge test with an alternative skin test-negative ICM. The 2 patients who underwent computed tomography with an alternative skin test-negative ICM tolerated the medium. CONCLUSIONS: Skin tests are useful for the diagnostic workup in patients with an allergic IHR to ICM. Since ICM cannot be avoided in many patients because they are irreplaceable in some diagnostic or therapeutic techniques, an alternative safe ICM should be investigated for future procedures. We propose the use of controlled challenge tests based on skin test results to address this need in skin test-positive reactions in order to identify an alternative non-cross-reactive ICM.

Anaphylaxis to oral iron salts. desensitization protocol for tolerance induction.

Allergies to iron salts are seldom reported. We studied a patient with iron-deficiency anemia who had suffered anaphylactic reactions caused by oral iron salts. An allergy study was performed using single-blind, placebo-controlled oral challenge and skin tests with various iron salts as well as excipients in commercial formulations. Oral challenges were positive for 2 of the commercial formulations of iron salts. Intradermal tests with ferrous sulphate and ferrous lactate also showed positive results. All of the cutaneous tests using the excipients were negative. A desensitization protocol was designed which enabled us to readminister ferrous sulphate, although antihistamines were necessary to guarantee good tolerance to iron salts. We report a patient with allergy to iron salts, positive skin tests, and positive controlled challenge. We highlight the desensitization protocol designed to complete the therapeutic management of the anemia.

Unilateral conjunctival chemosis as a unique symptom of nonsteroidal anti-inflammatory drug intolerance.

Patients with nonsteroidal anti-inflammatory drug (NSAID) intolerance usually have cutanous-mucosal or/and respiratory symptoms. We report the case of a patient who developed several episodes of left-eye conjunctivitis, manifested as conjunctival chemosis, with no other symptoms, after taking metamizole and other unidentified NSAIDs. We performed both a single blind placebo-controlled oral challenge test and conjunctival challenge test with different NSAIDs. The single blind placebo-controlled oral challenge was positive to ketoprofen and diclofenac. The conjunctival challenge with diclofenac and flurbiprofen was negative. The patient tolerated celecoxib and nabumetone. We believe this to be an exceptional case of NSAID intolerance as conjunctival chemosis has not hitherto been included in any of the classic types of pseudoallergic reactions.

Diagnosis and management of hypersensitivity reactions caused by oxaliplatin.

Hypersensitivity reactions to oxaliplatin have been increasing since its introduction at the end of the 1990s, but allergy tests with antineoplastic drugs are rarely used to aid diagnosis. We describe 5 cases in which hypersensitivity reactions to oxaliplatin after several courses of chemotherapy were managed by allergy testing and desensitization. Skin prick tests were negative at 1 mg/mL in all patients, positive at 10 mg/mL in 2 tested patients, and negative in 10 control subjects. Intradermal tests were positive and not irritant at 0.01 to 0.001 mg/mL concentrations. A desensitization protocol with increasing concentrations and flow rates was successfully completed in all patients. We conclude that prick and intradermal skin tests are useful in the diagnosis of hypersensitivity reactions to oxaliplatin and that the desensitization protocol performed avoided discontinuation of chemotherapy in all patients.

Allergy to chironomid larvae (red migde larvae) in non professional handlers of fish food.

UNLABELLED: Chironomids are insects which inhabit wetlands. In countries such as Sudan, The United States. Egypt and Japan they are the cause of serious environmental allergy. In Europe, and particularly in Spain, allergy to Chironomids is infrequent and has only been described in patients who handle Chironomid larvae which form part of certain fish foods. MATERIALS AND METHODS: We report a case of hypersensitivity to the Chironomid Midge (Chironomus thummi thummi) in a 23-year-old patient who on two occasions, after being in contact with fishfood, suffered rash, rhinoconjunctivitis, dyspnea and dysphagia. A Prick test was carried out with the habitual pneumoallergens, Chironomid Midge extract (PBS: 1.3 mg/ml), Common Mosquito (Culex pipiens), Squid, Mussel, Prawn and Anisakis. Conjunctival provocation was also carried out with Chironomid Midge extract; detection of specific IgE for Chironomid Midge, Common Mosquito (Aedes comunis), Mussel, Squid, Shrimp, Anisakis, house dust and house mites by means of the CAP technique; detection of IgE by means of ELISA in response to Chironomid Midge, Aedes mosquito, Squid, Prawn, Mussel and Anisakis; ELISA-inhibition and Immunoblott-inhibition. RESULTS: The positive results of the cutaneous tests, the detection of specific IgE and conjunctival provocation confirmed the existence of an IgE-mediated mechanism. In our patient, the in vitro techniques demonstrated cross reactivity with the Common Mosquito. CONCLUSIONS: We report on a patient with a case history of rhinoconjunctivitis, rash, dyspnea, and dysphagia after handling fish food. The etiological agent was the Chironomid larvae. The sensitization of our patient has been demonstrated by means of in vivo and in vitro techniques.

Cross-reactivity among p-amino group compounds in sulfonamide fixed drug eruption: diagnostic value of patch testing.

We studied 28 patients with fixed drug eruption (FDE) caused by sulfonamide antibiotics to investigate cross-reactivity between sulfonamide derivatives and p-amino compounds and to explore the usefulness of patch testing, as an alternative to controlled oral challenge testing (COCT), in diagnosis within this clinical area. COCT with sulfamethoxazole (SMX), sulfadiazine (SDZ), sulfamethizole (SMZ), furosemide (FU), procaine (PRO) and glipizide (GPZ) was performed. Patch testing (PT) with SMX and SDZ was carried out. In all patients, the diagnosis of FDE was confirmed by positive COCT and allergy to trimethoprim ruled out by COCT. 42.8 and 31.8% of the SMX-induced FDE patients reacted to SMZ and SDZ, respectively. All patients (n = 28) tolerated FU, PRO and GPZ. COCT performed with the 3 sulfonamide antibiotics in 12 patients was positive in 2 subjects with the 3 drugs, in 2 patients only with SMX and SMZ and in the remaining 8, SMX was the only causative drug. PT was positive in 5 of 25 patients positive on COCT. The probability of obtaining a positive PT was higher among patients who had a residual lesion than that among those who lacked this. Cross-reactivity between different sulfonamide antibiotics is thus variable, being most likely between SMX and SMZ. We have found no cross-reactivity between sulfonamide antibiotics and other sulfonamide derivatives or p-amino drugs in FDE. PT is a useful tool in the diagnosis of FDE, especially if there are residual lesions, because it avoided the need for COCT in 20% of patients.

Characterization of allergens secreted by Anisakis simplex parasite: clinical relevance in comparison with somatic allergens.

BACKGROUND: Diagnostic methods for the study of allergic reactions to Anisakis simplex (A.s.) based on whole-body extracts of the larva are clearly insufficient. OBJECTIVES: To study the allergenicity of the proteins secreted by the parasite. Comparison with somatic antigens and determination of their clinical importance in allergic patients were also addressed. METHODS: An excretory/secretory (E/S) extract was produced by culturing third-stage A.s. larvae. It was used to perform immediate skin tests and to determine specific IgE in 10 patients diagnosed with allergy to A.s. Both tests were compared with the results obtained with the whole-body extract (somatic (S)). The molecular weight (MW) of their allergens was determined by immunoblotting, and a single-blind placebo-controlled oral challenge with E/S proteins was performed. Finally, allergens' resistance to gastric pepsin and acid pH was explored. RESULTS: A.s. larvae secreted allergens more potent than those present in the S extract. The skin prick test wheal area produced by E/S molecules and the absorbance obtained in the determination of specific IgE with these allergens (ELISA) were 5.8 times bigger than those obtained with S extract. MW allergens of 72 and 56 kDa in E/S extracts and those of 56, 48 and 43 kDa in S extract were recognized by more than 50% of the patients. Partial cross-reactivity between them was revealed by immunoblotting inhibition studies. Oral challenge with E/S extract (up to 479 microg) was negative in all the patients. Treatment of E/S proteins with gastric pepsin inhibited the binding of the E/S allergens for specific IgE. The acid pH did not affect the overall binding of IgE to E/S extract. It decreased by 15.23% and 19.96% at pH 4 and 2, but the difference was not statistically significant. CONCLUSION: A.s. secretes allergens more potent than somatic antigens and should be used in the diagnostic procedures. These allergens are inactivated by the pepsin, which supports the theory that live larva is necessary to induce an allergic reaction in most of the patients.