Alicia Prieto-García

Mast cell restricted mouse and human tryptase·heparin complexes hinder thrombin-induced coagulation of plasma and the generation of fibrin by proteolytically destroying fibrinogen

Background: Mast cells contain tryptase·heparin complexes. Results: Fibrinogen is preferentially cleaved by these complexes. Conclusion: A major way mast cells prevent the generation of fibrin and fibrin-platelet clots in inflammatory sites is by their exocytosed tryptase·heparin complexes proteolytically destroying fibrinogen. Significance: The use of recombinant tryptase·heparin complexes might be an effective way to prevent blood coagulation in the clinic. The mouse and human TPSB2 and TPSAB1 genes encode tetramer-forming tryptases stored in the secretory granules of mast cells (MCs) ionically bound to heparin-containing serglycin proteoglycans. In mice these genes encode mouse MC protease-6 (mMCP-6) and mMCP-7. The corresponding human genes encode a family of serine proteases that collectively are called hTryptase-β. We previously showed that the α chain of fibrinogen is a preferred substrate of mMCP-7. We now show that this plasma protein also is highly susceptible to degradation by hTryptase-β· and mMCP-6·heparin complexes and that Lys575 is a preferred cleavage site in the protein α chain. Because cutaneous mouse MCs store substantial amounts of mMCP-6·heparin complexes in their secretory granules, the passive cutaneous anaphylaxis reaction was induced in the skin of mMCP-6+/mMCP-7− and mMCP-6−/mMCP-7− C57BL/6 mice. In support of the in vitro data, fibrin deposits were markedly increased in the skin of the double-deficient mice 6 h after IgE-sensitized animals were given the relevant antigen. Fibrinogen is a major constituent of the edema fluid that accumulates in tissues when MCs degranulate. Our discovery that mouse and human tetramer-forming tryptases destroy fibrinogen before this circulating protein can be converted to fibrin changes the paradigm of how MCs hinder fibrin deposition and blood coagulation internally. Because of the adverse consequences of fibrin deposits in tissues, our data explain why mice and humans lack a circulating protease inhibitor that rapidly inactivates MC tryptases and why mammals have two genes that encode tetramer-forming serine proteases that preferentially degrade fibrinogen.

Autoimmune progesterone dermatitis: clinical presentation and management with progesterone desensitization for successful in vitro fertilization

OBJECTIVE To report clinical cases of autoimmune progesterone (P) dermatitis, its relationship to IVF, and the potential for P desensitization to treat these cases to achieve viable pregnancies. DESIGN Clinical description. SETTING Institutional hospitalary practice. Allergy Division. PATIENT(S) Six patients from the Allergy Clinic consulting for cyclic rashes or anaphylaxis related to the luteal phase of the menstrual cycle. Three of the conditions were related to IVF. INTERVENTION(S) Skin tests were performed with P. For IVF, rapid 8- and 10-step P desensitization protocols were performed, with increasing doses administered every 20 minutes via intravaginal suppositories. A rapid oral desensitization protocol was performed in one patient who required an oral contraceptive for uterine bleeding. MAIN OUTCOME MEASURE(S) Progesterone skin test results. Tolerance to P desensitization. Achievement of viable pregnancies. RESULT(S) Skin tests were positive in all patients and negative in 10 controls. Desensitization was successful in four patients: three patients for IVF, resulting in viable pregnancies. Another patient achieved tolerance to oral contraceptives. CONCLUSION(S) Women with autoimmune P dermatitis can be desensitized successfully to P. We provide the first evidence of successful P desensitization in patients requiring IVF culminating in successful pregnancies.

Systemic mastocytosis presenting as IgE-mediated food-induced anaphylaxis: A report of two cases

Anaphylaxis is a common manifestation in patients with systemic mastocytosis (SM), particularly in adults with indolent SM without skin involvement (ISMs ), with an estimated prevalence of 20% to 49%. The association between ISMs and hymenoptera venom anaphylaxis is well established. In contrast, IgE-mediated anaphylaxis secondary to drugs or foods has been reported in patients with SM only sporadically. We report 2 patients presenting with IgE-mediated food-induced anaphylaxis as the manifestation of an underlying ISMs .

First case of allergy to nivolumab

Nivolumab (Opdivo) is a humanized IgG4 anti-PD-1 monoclonal antibody used to treat different types of cancer, mainly metastatic skin and lung tumours, and, more recently, metastatic liver cancer as part of some clinical trials. Nivolumab works as an inhibitor, blocking the binding of the PD-1 T-receptor to its ligands, PD-L1 and PD-L2. This blocking derepresses T cells that can then effectively attack the tumor. Some psoriasiform eruptions have been described in relation to this drug, but there are no cases of any IgE-mediated adverse reactions previously described. We present the case of a 57-year-old woman diagnosed with hepatocellular carcinoma in 2015. Previous treatment with sorafenib was well tolerated. In January 2016, because of progression of her disease, she started treatment with nivolumab and ipilimumab, as part of a new clinical trial. In the third cycle, at the end of intravenous infusion of nivolumab, she immediately developed facial flushing, hives on her face and neck, and eyelid angioedema. Vital signs demonstrated blood pressure 110/75 mm Hg, pulse rate 70 bpm, and pulse oximetry 99% on room air, with no other systemic symptoms. No tryptase levels were taken at that time. The infusion was stopped and the symptoms disappeared spontaneously in approximately 45 minutes. After that, she received ipilimumab and tolerated it well. The patient was referred to our allergy department. In vivo testing was undertaken after informed consent was signed. The skin prick test with nivolumab at a concentration of 1 mg/mL (1/10) was negative on immediate reading. The intradermal (ID) test with nivolumab at 0.1 mg/mL (1/100) elicited a positive reaction (8 mm wheal) at 15 minutes. Negative and positive controls were carried out with saline and histamine, respectively. Identical skin tests in 5 patients included in the same clinical trial receiving treatment with nivolumab but without symptoms were all negative. In vitro testing, including basal tryptase levels, was normal (1.4 mg/L). Moreover, anti-nivolumab IgE antibodies measured by SDS-PAGE immunoblotting, according to the Laemmli technique in reducing and nonreducing conditions (with and without 2-mercaptoethanol, respectively), with serum dilutions of 1/5, 1/10, and 1/20, and the enzyme allergosorbent test were undetectable. Because of the excellent response of the patient to nivolumab, the oncologists decided that she needed to continue receiving the same drug. We performed the first desensitization of 240 mg of nivolumab with a 12-step protocol in 3 bags: bag A at a concentration of 0.01 mg/mL, bag B at 0.1 mg/mL, and bag C at 0.5 mg/mL, premedication with oral aspirin 300 mg, montelukast 10 mg, intravenous dexchlorpheniramine 5 mg, ranitidine 50 mg, and hydrocortisone 200 mg. During the infusion of bag C, at 160 mL/h, after 50 minutes, she presented with right eyelid pruritus and angioedema, without other symptoms. The infusion was stopped and she received intravenous dexchlorpheniramine 5 mg and hydrocortisone 200 mg, and her symptoms resolved in less than 30 minutes. We finished the desensitization at 160 mL/h with no additional reactions. After that, we performed further desensitizations using a desensitization protocol with more modifications (Table I), adding steps in bag C (80 mL/h, 120 mL/h, 140 mL/h, and 160 mL/h), and adding pretreatment with dexchlorpheniramine at the step before the step with symptoms. Despite those modifications, the patient always had the same eyelid angioedema at 120 mL/h. Then we decided to administer desloratadine 5 mg every 24 hours for the 3 days before the treatment, and she has had no reactions since the 11th desensitization and has tolerated 9 desensitizations with the same modified protocol as of this report. To our knowledge, there is no previous literature published about an immediate hypersensitivity reaction to nivolumab. This is the first case with a positive skin test and a desensitization protocol reported. In this case, the symptoms and the positive ID test suggest that there is an IgE-mediated mechanism, although we could not prove this hypothesis by the in vitro test. This reaction was amenable to rapid desensitization as previously reported for other biologic agents. We recommend performing skin tests in patients with reactions to new biologic

Mast Cell–Restricted Tetramer-Forming Tryptases and Their Beneficial Roles in Hemostasis and Blood Coagulation

Tetramer-forming tryptase (hTryptase-β) was recently discovered to have a prominent role in preventing the internal accumulation of life-threatening fibrin deposits and fibrin-platelet clots. The anticoagulant activity of hTryptase-β is an explanation for the presence of hemorrhagic disorders in some patients with anaphylaxis or mastocytosis. The fragments of hFibrinogen formed by the proteolysis of this prominent protein by hTryptase-β could be used as biomarkers in the blood and/or urine for the identification and monitoring of patients with mast cell-dependent disorders. Recombinant hTryptase-β has potential to be used in clinical settings where it is desirable to inhibit blood coagulation.

Immediate reactions to iodinated contrast media

BACKGROUND Immediate hypersensitivity reactions (IHRs) to iodinated contrast media (ICMs) remain a common clinical concern. Positive skin test and basophil activation test results suggest a specific IgE-mediated mechanism in some cases. Skin test and controlled challenge test (CCT) are useful to manage these patients. OBJECTIVE To study clinical and allergologic features of IHRs to ICMs in a Spanish tertiary hospital during a 7-year period. METHODS Demographic and clinical data concerning the reaction were recorded. Patients treated at the Allergy Department of Hospital General Universitario Gregorio Marañón, Madrid, Spain, underwent skin tests. In those with positive results, CCTs with an alternative skin-test-negative ICM was performed. Global reaction rate was calculated and compared for each ICM. RESULTS A total of 342 reactions occurred in 329 patients. Cutaneous symptoms were the most common (87.7%). A total of 196 patients underwent an allergy workup, 15 (7.6%) of whom had positive skin test results. Reactions were more severe in patients with positive vs negative skin test results (grade 1, 46.7% vs 73.6%; grade 2, 33.3% vs 20.9%; grade 3, 20% vs 5.46%; P < .05). Three patients had cross-reactivity to 3 ICMs, all including ioversol and iomeprol. Six patients allergic to iopamidol tolerated ioversol and 1 tolerated iomeprol. Four patients allergic to ioversol and 1 allergic to iomeprol tolerated iopamidol. The global reaction rate was 0.2%, differing for each ICM (iopamidol, 0.14%; ioversol, 0.2%; and iomeprol, 0.4%; P < .001). Positive skin test results were found in a low percentage of patients in whom skin test-based CCT identified an alternative non-cross-reactive ICM. Low-grade cross-reactivity was found, especially between iopamidol and ioversol. Reactions were more severe in patients with positive skin test results. The reaction rate was greater for iomeprol compared with iopamidol (reaction rate, 2.8%) and ioversol (reaction rate, 2%). CONCLUSION This study identified a possible underlying specific IgE-mediated mechanism by positive skin test result in a low percentage of patients with IHRs to ICMs. In these patients, the CCT based on skin test results was useful for identifying an alternative non-cross-reactive ICM. More studies are needed to investigate the underlying mechanism in patients with IHRs and negative skin test results.

Anaphylactic shock caused by impurities in orgotein preparations

Previously reported allergic reactions to orgotein (superoxide dismutase) injections has assigned responsibility to this molecule, which is obtained from bovine liver. We report an anaphylactic shock probably caused by impurities contained in an orgotein preparation. Prick test to Peroxinorm (orgotein), BSA, and cow liver extract were positive but resulted negative with chymotrypsin, milk, meat and cow epithelium extracts. Tryptase levels determined 3, 24 hours and 15 days after the shock measured 6.32, 0.81 and 0.84 U/L respectively. Detection of specific IgE to Peroxinorm, BSA and chymotrypsin by ELISA was negative and positive to cow liver. Specific IgE to milk and cow epithelium by Pharmacia CAP system was negative. Immunoblotting with Peroxinorm revealed IgE specific bands at an apparent M.W of 67, 51, 56 and 16 kDa; immunoblotting with cow liver revealed bands at 72, 56, 50 and 36 kDa; immunoblotting with BSA and chymotypsin were negative. This case emphasises the role that 20 % of impurities of the pharmaceutical preparation may have in immediate hypersensitivity reactions.

Fatal anaphylaxis caused by gadolinium due to beta-tryptase–induced hemorragic diathesis

Anaphylaxis to gadolinium occurs in 0.001% to 0.01% of administrations. Although it has increased over the last decades, gadolinium is considered to be very safe, rarely associated with death. A 64-year-old woman with personal history of hypertension, ex-smoker, dyslipidemia, and obesity was diagnosed with septum hypertrophic cardiomyopathy after a first episode of atrial fibrillation with spontaneous cardioversion. Ventricular ejection fraction was normal and she was in class I-II/IV for dyspnea. She was being treated with atenolol, lisinopril, rosuvastatine, torasemide, and acenocoumarol. She had no history of atopy, drug allergy, or asthma and she had never been exposed to gadolinium-based contrast media. She presented at the outpatient clinic to undergo a cardiac magnetic resonance. The patient’s medications were not discontinued before the study. At her arrival, her blood pressure was 170/80 and heart rate (HR) was 45 bpm. Intravenous gadobenate dimeglumine (20 mL) (Multihance, Bracco Diagnostics Inc., Cranbury, NJ) was administered. Two minutes later, she complained of malaise and myalgia, and 1 minute later showed a decreased level of consciousness. The procedure was immediately stopped. At that time, physical examination showed cyanosis, HR 40 bpm, systolic blood pressure 80 mm Hg, and oxygen saturation 85%. Epinephrine, dexclorfeniramine, and hydrocortisone were administered. The patient went into cardiorespiratory arrest with asystole. Advanced cardiopulmonary resuscitation was initiated with intravenous epinephrine, fluids, bicarbonate, and norepinephrine, followed by use of an Extra Corporeal Membrane Oxygenation device. A 20-cm hematoma developed on her thighs at the site of vascular punctures along with massive gastrointestinal bleeding (>3 L), through nasogastric and orotracheal tubes. Blood tests showed pH 6.81, PaCO2 29 mm Hg, HCO3 5 mEq/L, lactate more than 15 mM, a decreasing hemoglobin (8.2 to 5.1 g/dL), and low platelet (88 10/L) count. Fibrinogen and clotting time tests were undetectable despite treatment with vitamin K, protamine sulfate, coagulation factor concentrates, and fresh frozen plasma together with red cell and platelet transfusions. Unfortunately, hemodynamic control was not achieved and the patient died within 20 hours of the gadolinium injection. A serum sample obtained from the femoral artery 50 minutes after the onset of symptoms reported 63 ng/mL for total tryptase (normal, <11.4 ng/mL) (UniCAP, Phadia, Thermo Fisher, Upsala, Sweden) and 17 ng/mL for mature beta-tryptase (normal, <1 ng/mL) (Virginia Commonwealth University, Richmond, Va). Serum tryptase is a biomarker for systemic anaphylaxis. Proea/b-tryptases are continuously secreted from mast cells (MCs) as inactive proenzymes. The level of protryptase reflects genetic factors, and also the total body MC burden, whereas mature tryptases are stored in MC granules and released as tetramers, including active beta-tryptase, upon MC activation. Total tryptase levels are elevated at baseline in most patients with systemic mastocytosis, whereas beta or total tryptase levels peak about 1 hour after clinical onset of systemic anaphylaxis, and then decline, returning to baseline by about 4 hours. A total tryptase assay, which is widely available, measures both a/b, pro/mature tryptases. High total tryptase levels are found after anaphylaxis, but these must be compared with the respective baseline levels to distinguish between MC activation and increased MC burden. In turn, an increased beta-tryptase level (available from LBS Lab in Virginia) is the pathognomonic finding in systemic anaphylaxis with ratios of total to beta-tryptase typically being less than 10. Measuring beta-tryptase is essential to diagnose postmortem anaphylaxis, when a baseline blood sample is not available. An elevated beta-tryptase level in serum (>10 ng/mL) increases the likelihood that anaphylaxis caused the death. However, high tryptase values have also been found in deaths of other causes, casting uncertainty as to how MCs were activated to release this protein, but nevertheless, still raising the possibility of an MC activationerelated death. Also, MC lysis, conceivably, may increase tryptase levels in blood, so postmortem serum samples should be taken as soon as possible and from peripheral blood vessels. Laroche et al compared total tryptase blood levels in patients with severe allergic reactions during anesthesia and patients with shock from other causes, including patients with cardiac arrest, showing that resuscitation maneuvers and treatment of shock, by themselves, did not induce an increase in tryptase levels. An elevated tryptase level strongly supported MC activation and the diagnosis of anaphylaxis. In this patient, we found high total and beta-tryptase levels in a serum sample extracted from a femoral artery 1 hour after the onset of symptoms, with a total/beta-tryptase ratio of 3.7, indicating premortem MC activation. Whether gadobenateinduced anaphylaxis was IgE-mediated was not addressed, because allergy skin tests could not be performed and an in vitro drug-specific IgE test has not yet been developed. Previous treatment with b-blocker and angiotensin-converting enzyme inhibitor drugs could have blunted the physiologic