Anaphylaxis: Advances in the Past 10 Years

In the past 10 years, anaphylaxis has grown into its own special area of study within Allergy-Immunology, both at the bench and at the bedside. This review focuses on some of the most clinically relevant advances over the past decade. These include simplified and more inclusive diagnostic criteria for adults and children, uniform definition of biphasic anaphylaxis, and improved systems for objective severity grading. Studies reported in the past decade have led to improved understanding of normal and abnormal regulation of mast cell function, translating into better diagnostic and therapeutic approaches to patients with anaphylaxis. Research has provided improved recognition and treatment of mast cell disorders and has identified a new condition, hereditary α-tryptasemia, that may impact anaphylactic syndromes. We have learned to recognize new causes (α-gal), new pathways (Mas-related G protein-coupled receptor-X2), and many risk factors for severe anaphylaxis. The stability of epinephrine in autoinjectors was reported to be very good for several years after the labeled expiry date, and it can tolerate freezing and thawing. Repeated and prolonged exposure to excessive heat leads to degradation of epinephrine activity. New treatments to prevent severe anaphylaxis have been described, using new ways to block the IgE receptor or modulate intracellular signaling pathways.

Hypereosinophilic syndrome: endomyocardial biopsy versus echocardiography to diagnose cardiac involvement

OBJECTIVE

To compare echocardiograms and endomyocardial biopsies to diagnose cardiac involvement in hypereosinophilic syndrome.

METHODS

We examined the agreement between echocardiography and endomyocardial biopsies to detect cardiac involvement in hypereosinophilic syndrome by reviewing cases identified as hypereosinophilia or hypereosinophilic syndrome in Mayo Clinic databases from January 1978 through June 2009. Single-organ cases of eosinophilia such as eosinophilic fasciitis and eosinophilic gastroenteritis were excluded. We recorded echocardiogram and endomyocardial biopsy results including biopsy staining for eosinophil granule major basic protein (if performed). Clinical and laboratory features documented included presenting symptom(s), maximum total eosinophil count, dose of prednisone (if any) and eosinophil count at the time of endomyocardial biopsy, cardiac enzymes, serum tryptase level, electrocardiogram result, the result of testing for the FIP1L1-PDGFRA fusion gene, complications associated with the biopsy procedures and available follow-up information.

RESULTS

From a total of 387 patients' records screened 288 met the criteria for hypereosinophilic syndrome and of these 240 had echocardiograms. Among these patients there were 138 normal echocardiograms, 67 had echocardiograms without findings of hypereosinophilic syndrome but with one or more other abnormalities, and 35 had echocardiograms with findings consistent with hypereosinophilic syndrome. Twenty-five patients from this group of 35 patients had both echocardiogram and endomyocardial biopsy. In 15 patients there was agreement between both endomyocardial biopsy and echocardiography as to the presence (n = seven) or absence (n = eight) for findings of cardiac involvement. In 10 of 25 patients test results diverged: 3 patients with positive echocardiographic changes did not have confirmatory findings by endomyocardial biopsy and seven patients with positive biopsy findings had echocardiograms without findings of hypereosinophilic syndrome.

CONCLUSIONS

Echocardiograms and endomyocardial biopsies agree for presence or absence of cardiac involvement 60% of the time. Endomyocardial biopsy detected cardiac involvement in 7 patients in whom the echocardiogram was negative for findings of hypereosinophilic syndrome.

Tolerance and Efficacy with Simultaneous Use of Two Monoclonal Antibodies for a Patient with Hypereosinophilic Syndrome and Ulcerative Colitis

The development and utilization of monoclonal antibodies (mAbs) have been of great interest in all fields of medicine. A substantial increase in the production and development of mAbs has occurred because these biologic agents are proving to be effective and less toxic given their targeted mechanism of action. However, data are limited on coadministration of two or more mAbs. With the increasing availability of mAbs and the comorbidities of some patients, assessment is needed of the ability to safely use multiple mAbs for an individual patient. Although the efficacy of coadministered mAbs may be inferred from their specific targets, we could find no literature reporting such a finding. Herein, we report our experience using two different classes of mAbs to treat hypereosinophilic syndrome and ulcerative colitis in a single patient.

Mast cell sarcoma: clinical management

Mast cell sarcoma is a disorder that results in abnormal mast cells as identified by morphology, special stains, and in some publications, c-kit mutation analysis. It affects animal species such as canines more commonly than humans. In humans it is a very rare condition, with variable clinical presentation. There is no standard therapy for the disorder. It can affect any age group. It is occasionally associated with systemic mastocytosis and/or urticaria pigmentosa. The prognosis of mast cell sarcoma in published literature is very poor in humans.

Presentation of untreated systemic mastocytosis as recurrent, pulseless-electrical-activity cardiac arrests resistant to cardiac pacemaker

Recurrent, pulseless-electrical-activity (PEA) cardiac arrests were the novel presentation of untreated systemic mastocytosis in an 85-year-old woman who lacked cutaneous findings of mastocytosis. Despite prior implantation of a dual-chamber cardiac pacemaker 3 weeks previously for similar spells, she experienced a PEA arrest accompanied by flushing, increased urinary N-methylhistamine excretion and serum tryptase values on the day of presentation to our clinic. Bone marrow biopsy findings conducted to rule out breast cancer metastases showed 30% mast cell infiltration, aberrant expression of CD25 and a positive c-kit Asp816Val mutation. Treatment with a combination of H1 and H2 receptor blockers reduced flushing and eliminated hypotension. Maintenance medication included aspirin, cetirizine, ranitidine, montelukast, oral cromolyn sodium and an epinephrine autoinjector (as needed). At 6-month follow-up, the patient remained free of PEA arrests, flushing, or any clinical signs of mastocytosis or mast cell degranulation. PEA cardiac arrests may therefore be a presenting sign of untreated systemic mastocytosis.

Systemic mastocytosis in the elderly

"Later onset" of systemic mastocytosis (SM) has been associated with a poorer prognosis. We examined clinical and laboratory findings, associated disorders, and survival in an older mastocytosis population. After receiving Mayo Clinic Institutional Review Board approval, we identified 42 patients aged 70 years and older at the time of diagnosis of SM. Associated disorders, cytogenetic abnormalities, laboratory findings, and survival were recorded. Only 10 patients had no associated hematologic disorder. Single or multiple chromosomal abnormalities, exclusive of the KIT Asp816Val mutation, were detected in eight patients (19%). KIT Asp816Val mutation was present in 14 patients, negative in three, and not tested in 25. Slight to marked bone marrow hypercellularity was observed in 33 patients (79%). Concurrent hematologic abnormalities included chronic myelomonocytic leukemia (n = 7), acute myelocytic leukemia (n = 1), myelodysplastic syndrome (MDS; n = 7), eosinophilia (n = 7), myelofibrosis (n = 1), myeloproliferative disorder (n = 1), multiple myeloma (n = 1), B-cell lymphoma (n = 1), and thrombocytopenia (n = 4). Eight patients had a hematologic disorder that preceded the diagnosis of SM. Tryptase levels were elevated in 38 of 39 patients tested. Survival from the diagnosis of SM was poor for patients with associated thrombocytopenia, leukemias, and MDS. In conclusion, patients with SM diagnosed at age 70 or older have an increased risk of secondary hematologic disorders and abnormal laboratory findings. Cytogenetic abnormalities are common, and survival is short in many SM patients with associated leukemias, MDS, or eosinophilia.

Eosinophilic esophagitis: allergic contribution, testing, and management

Both basic science and clinical data indicate a strong role for allergy as a cause of eosinophilic esophagitis. As a result, one of the desired goals of therapy is identification and elimination of food antigens that trigger the allergic inflammatory pathway. Traditional methods for identification of causative food antigens include induction of symptoms with exposure to the antigen, demonstration of serum IgE antibodies against antigens and induction of immediate (IgE) or delayed (Th2) reactions against dermal instillation of antigens. Although some data support the use of these tests in patients with eosinophilic esophagitis, they are limited in this disease. This limitation results from an inability to provoke recognizable symptoms and a lack of concordance between allergies identified in the skin and the blood with the antigens that trigger esophageal disease. As a result, allergy therapy in eosinophilic esophagitis consists of global elimination of food antigens with an elemental diet or exclusion of the most common antigens. As compliance is difficult with these strategies, the mainstay of allergy therapy in eosinophilic esophagitis has become the use of medications that blunt the allergic pathway such as steroids with a future aimed toward more specific inhibitors of this pathway in eosinophilic esophagitis specifically.

Increased numbers of eosinophils, rather than only etiology, predict histologic changes in patients with esophageal eosinophilia

BACKGROUND & AIMS

It can be a challenge to differentiate individuals with eosinophilic esophagitis (EoE) from those with gastroesophageal reflux disease (GERD). We investigated differences in histologic and eosinophil patterns and numbers of mast cells between patients with these disorders.

METHODS

We performed histologic analyses and immunohistochemical assays for eosinophil-derived neurotoxin (EDN), major basic protein (MBP), and tryptase, using biopsy samples from 10 patients with GERD (positive results from a pH study and response to proton pump inhibitors), Barrett's esophagus, or EoE (negative results from a pH study and positive response to budesonide). Patients were matched for degree of eosinophilia.

RESULTS

Samples from patients with EoE, GERD, or Barrett's esophagus had similar increases in concentrations of eosinophils. Patients with GERD or EoE did not differ in amount of basal zone hyperplasia, microabscesses, spongiosis, eosinophil distribution, maximum eosinophils/high-power field (HPF), or composite histologic scores. Samples from all 3 groups had high levels of EDN and MBP; the levels of eosinophil products were correlated (ρ = 0.93). Extracellular staining for EDN was greater than intracellular staining (2.67 of 3 vs 1.86 of 3); levels tended to be greater in samples from patients with EoE than GERD (P = .05) or Barrett's esophagus (P = .06). Detection of EDN correlated with peak numbers of eosinophils/HPF (ρ = 0.6 for intracellular and extracellular staining). Peak numbers of tryptase-positive mast cells/HPF were significantly greater in samples from patients with EoE than GERD or Barrett's esophagus (P = .01 and .005, respectively). The Spearman correlation between eosinophil and mast cell density was a ρ value of 0.2.

CONCLUSIONS

Biopsy samples from patients with GERD and EoE, matched for esophageal eosinophilia, have similar changes in histology and levels of EDN and MBP, whereas mast cells from patients with EoE have higher levels of these products. The presence of esophageal eosinophils, rather than etiology, could be the most important determinant of epithelial response.

Prevention of mast cell activation disorder-associated clinical sequelae of excessive prostaglandin D(2) production

BACKGROUND

Patients with systemic mastocytosis have increased numbers of mast cells in the bone marrow and other organs, such as the liver, spleen, gastrointestinal tract and skin. Symptoms result from the local and remote effects of mediator release from mast cells and from the local effects of increased mast cell numbers in various organs. Patients with mast cell activation experience many of the same clinical symptoms as do patients with systemic mastocytosis from chronic or spontaneous release of mast cell mediators. We report 4 patients with mast cell activation symptoms from selective release of prostaglandin (PG) D(2), but not histamine, and their improvement with aspirin therapy.

METHODS

Bone marrow biopsy specimens obtained from 4 patients with symptoms suggestive of mastocytosis were examined by tryptase immunostaining. Baseline levels of serum tryptase and urinary 11beta-PGF(2)(alpha) and N-methylhistamine were obtained. In 2 of the 4 patients, urinary 11beta-PGF(2)(alpha) and N-methylhistamine samples were also measured during acute symptoms.

RESULTS

Baseline increase in urinary excretion of the PGD(2) metabolite 11beta-PGF(2)(alpha) was found in 2 patients. In the remaining 2 patients, baseline levels of urinary 11beta-PGF(2)(alpha) and N-methylhistamine were normal, but during acute symptoms, the excretion of 11beta-PGF(2)(alpha) increased markedly. Treatment with aspirin resulted in normalization of 11beta-PGF(2)(alpha) excretion in the 2 patients with elevated baseline levels and in prevention of symptoms in all 4 patients.

CONCLUSIONS

These results suggest that mast cell activation may be manifested by a selective excessive release of PGD(2). These patients respond to administration of aspirin but not to antihistamines.

Eosinophilic esophagitis: is it all allergies?

Eosinophilic esophagitis (EE) is an increasingly recognized disorder in the adult population, most often manifested by symptoms of dysphagia and food impaction. Mechanisms involving eotaxin-3, interleukin 5, and signal transducer and activator of transcription 6 have been studied and may represent future therapeutic targets. Patients commonly have a personal and family history of atopy, and both food allergies and aeroallergens have also been investigated as triggers of EE. Traditional allergy-testing methods, including skin prick testing and specific IgE testing, have been used to identify food and environmental allergies. However, new studies suggest that patch testing could add to diagnostic accuracy in EE because the disorder might not be a classic type I allergic response. Although studies of treatment of adults with EE have thus far focused on swallowed fluticasone proprionate, many trials in children have assessed the efficacy of food elimination and elemental diets. These diets, which have been extremely successful in reducing symptoms, have also been shown to induce histological improvement and remission. No similar studies have been conducted in adults; the tolerability of such an intervention may prove more difficult in this population. This article reviews the underlying pathophysiology of EE and describes evolving options for more accurately identifying food and environmental allergies. We also discuss the pediatric trials using food elimination and avoidance diets and suggest that this type of intervention may be an important area of future research in the adult population.

Clinical and laboratory characteristics of 75 patients with specific polysaccharide antibody deficiency syndrome

BACKGROUND

There are limited studies of large cohorts of patients with specific polysaccharide antibody deficiency (SPAD) syndrome.

OBJECTIVE

To study the clinical and laboratory characteristics of patients with specific polysaccharide antibody deficiency syndrome.

METHODS

We retrospectively studied 75 patients with total IgG levels of at least 500 mg/dL and fewer than 9 of 12 responses to vaccination with pneumococcal vaccine polyvalent. Exclusion criteria included an IgG level less than 500 mg/dL, established immunodeficiency syndrome, and secondary immunodeficiency.

RESULTS

The most common clinical presentation was frequent infections (n = 69; 92%), including sinusitis (n = 53; 77%), pneumonia (n = 29; 42%), ear infections (n = 18; 26%), and bronchitis (n = 19; 28%). Other presentations were systemic infections (n = 5; 7%), autoimmune or rheumatic diseases (n = 6; 8%), and chronic diarrhea (n = 4; 5%). The median IgG2 level of patients with no response to pneumococcal vaccine polyvalent tended to be lower than that of patients with at least 1 response (150 vs 193 mg/dL, respectively; P = .06). There was no association between total IgG level (categorized as 500-600 or > or = 600 mg/dL) and frequency of infection (P = .43). Patients with fewer responses to pneumococcal vaccine polyvalent and a higher frequency of infections were more likely to receive intravenous immunoglobulin (IVIG) therapy (P = .01 and .003, respectively). Treatment with IVIG significantly reduced the number of infections (P < .001).

CONCLUSION

Patients with no response to pneumococcal vaccine polyvalent tended to have lower IgG2 levels; those with fewer responses were more likely to receive IVIG therapy.

Monoclonal gammopathies and malignancies in patients with chronic urticaria

BACKGROUND

Monoclonal gammopathy of undetermined significance (MGUS) has been described in association with chronic urticaria (CU) in patients with Schnitzler syndrome. Chronic urticaria may be a manifestation of hematologic malignancies.

METHODS

This study was conducted to evaluate the frequency and characteristics of MGUS or malignancy in patients with CU. The Mayo Clinic electronic database was reviewed to identify patients with the diagnosis of CU.

RESULTS

Of the 1639 patients presenting with CU between 1994 and 2001, 797 (49%) underwent laboratory evaluation for the presence of a coexisting monoclonal protein. Forty-seven CU patients had MGUS, 142 had a malignancy, and 24 had both. Fifteen percent of CU patients with MGUS had a hematologic malignancy compared with 0.9% of CU patients without MGUS (P < 0.001). Patients presenting with a new diagnosis of CU at an older age (> 56 years) were more likely to have associated underlying MGUS. The occurrence of MGUS in this group was higher than the reported incidence of MGUS in the general population.

CONCLUSIONS

Patients with CU younger than 43 years were unlikely to have associated MGUS or malignancy. A higher percentage of patients with CU and MGUS had an associated diagnosis of hematologic malignancy.

Genetic test indications and interpretations in patients with hereditary angioedema

Patients with hereditary angioedema (HAE) present with recurrent, circumscribed, and self-limiting episodes of tissue or mucous membrane swelling caused by C1-inhibitor (CI-INH) deficiency. The estimated frequency of HAE is 1:50,000 persons. Distinguishing HAE from acquired angioedema (AAE) facilitates therapeutic interventions and family planning or testing. Patients with HAE benefit from treatment with attenuated androgen, antifibrinolytic agents, and C1-INH concentrate replacement during acute attacks. HAE is currently recognized as a genetic disorder with autosomal dominant transmission. Other forms of inherited angioedema that are not associated with genetic mutations have also been identified. Readily available tests are complement studies, including C4 and C1-esterase inhibitor, both antigenic and functional C1-INH. These are the most commonly used tests in the diagnosis of HAE. Analysis of C1q can help differentiate between HAE and AAE caused by C1-INH deficiency. Genetic tests would be particularly helpful in patients with no family history of angioedema, which occurs in about half of affected patients, and in patients whose C1q level is borderline and does not differentiate between HAE and AAE. Measuring autoantibodies against C1-INH also would be helpful, but the test is available in research laboratories only. Simple complement determinations are appropriate for screening and diagnosis of the disorder.

Use of intravenous immunoglobulin in human disease: A review of evidence by members of the Primary Immunodeficiency Committee of the American Academy of Allergy, Asthma and Immunology

Human immunoglobulin prepared for intravenous administration (IGIV) has a number of important uses in the treatment of disease. Some of these are in diseases for which acceptable treatment alternatives do not exist. In this review we have evaluated the evidence underlying a wide variety of IGIV uses and make specific recommendations on the basis of these data. Given the potential risks and inherent scarcity of IGIV, careful consideration of the indications for and administration of IGIV is warranted.

Common variable immunodeficiency: test indications and interpretations

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder that can present with multiple phenotypes, all of which are characterized by hypogammaglobulinemia, in a person at any age. A specific genetic defect that accounts for all CVID phenotypes has not been identified, and it is likely that several distinct genetic disorders with similar clinical presentations are responsible for the observed variation. In this review, we summarize the known genetic mutations that give rise to hypogammaglobulinemia and how these gene products affect normal or abnormal B-cell development and function, with particular emphasis on CVID. Additionally, we describe specific phenotypic and genetic laboratory tests that can be used to diagnose CVID and provide guidelines for test interpretation and subsequent therapeutic intervention.

Selective antibody immune deficiency in a patient with Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome is a rare autosomal recessive disorder characterized by multiple congenital anomalies and various degrees of cognitive deficits. This condition results from a deficiency of 7-dehydrocholesterol reductase, a critical step in cholesterol biosynthesis. Children with Smith-Lemli-Opitz syndrome have frequent infections, particularly of the respiratory tract. Immunodeficiency, however, is not recognized as a part of this metabolic condition. Frequent infections are usually attributed to a decreased patient mobility and reduced respiratory effort secondary to muscular hypotonia and mental retardation, which are often present in affected individuals. We describe a patient with Smith-Lemli-Opitz syndrome and recurrent respiratory infections who was found to have a selective antibody deficiency. The immunological diagnosis was based on an absent immune response to Pneumovax. She also had no immunological response to hepatitis B vaccine and was unable to break down red cells with isoagglutinin B. Therapy with intravenous IgG (IVIG) was initiated. Infections were less severe, although they still occurred in a high frequency after initiation of the IVIG therapy. This finding prompts the need for a higher index of suspicion for an underlying immune deficiency in patients with Smith-Lemli-Opitz syndrome who present with recurrent and chronic infections. Early recognition and appropriate therapeutic interventions may decrease the severity of infections, prevent potentially fatal infections, and eventually improve the quality of life in these patients.

Angioedema related to the use of hyaluronidase in cataract surgery

PURPOSE

To report a series of cases of angioedema related to the use of hyaluronidase in cataract surgery.

DESIGN

Observational case series.

METHODS

Three eyes of three patients who had periorbital angioedema after phacoemulsification at the Mayo Clinic, Rochester, Minnesota, between April 2001 and May 2002 were retrospectively skin tested for allergies using the prick technique.

RESULTS

Skin testing was positive in all three patients for allergy to hyaluronidase (150 U/cc) and histamine control; and negative for prick control, 2% lidocaine, 1% cyclopentolate, 2.5% neosynephrine, 0.5% proparacaine, 0.3% ofloxacin, and thimerosal.

CONCLUSIONS

The use of hyaluronidase in ophthalmic anesthesia injection may cause immediate type hypersensitivity reactions such as angioedema.

Hypersensitivity to progesterone-in-oil after in vitro fertilization and embryo transfer

OBJECTIVE

To report the occurrence and management of pulmonary compromise, marked leukocytosis, and eosinophilia in a patient receiving P-in-oil after IVF and embryo transfer.

DESIGN

Case report.A tertiary referral reproductive medicine unit.

PATIENT(S)

A 29-year-old patient receiving P-in-oil supplementation after IVF embryo transfer.

INTERVENTION(S)

Extensive diagnostic testing and surveillance for hypersensitivity to P in sesame oil; development of an alternative oil-based P-in-oil suspension.

MAIN OUTCOME MEASURE(S)

Tolerance of alternative P vehicle; clinical pregnancy.

RESULT(S)

The patient tolerated an alternative P oil vehicle and successfully achieved a clinical pregnancy after frozen embryo transfer.

CONCLUSION(S)

Although rare, hypersensitivity reactions may occur in patients receiving P-in-oil supplementation after IVF embryo transfer. Testing for tolerance and subsequent use of alternative P vehicles may be an effective strategy in managing patients with sensitivity to P-in-oil.

Cockroach allergen-induced eosinophilic airway inflammation in HLA-DQ/human CD4(+) transgenic mice

Airway eosinophilic inflammation is a characteristic feature of allergic asthma. Exposure to allergens produced by the German cockroach (Blattella germanica) is a risk factor for allergic disease in genetically predisposed individuals, and has been linked to an increase in asthma morbidity among cockroach-sensitive inner city children. To determine the role and contribution of specific HLA class II in the pathogenesis of allergic airway inflammation in cockroach-induced asthma, we generated double-transgenic, double-knockout mice expressing human HLA-DQ8, HLA-DQ6, and CD4 molecules in the absence of mouse class II and mouse CD4. Mice were actively immunized and later challenged intranasally with cockroach allergen extract. These mice developed bronchoalveolar lavage fluid (BALF) eosinophilia and pulmonary eosinophilia. This was accompanied by an increase in total protein levels, IL-5, and IL-13 in BALF. There were also elevated levels of cockroach-specific serum IgG1 and total serum IgE. Histological analysis revealed peribronchial and perivascular eosinophilic inflammation in cockroach-treated mice. Other pathologic changes in the airways were epithelial cell hypertrophy and mucus production. Treatment with anti-DQ mAb significantly reduced pulmonary and BALF eosinophilia in cockroach allergen-sensitized mice. Abeta(0) mice and transgenic mice expressing human CD4 molecule alone (without class II) or human HLA-DQ8 molecule (without CD4) treated in the same fashion showed no eosinophilia in bronchoalveolar fluid and no pulmonary parenchymal inflammation. Our results provide direct evidence that HLA-DQ molecules and CD4 T cells mediate cockroach-induced eosinophilic inflammation in the airways.

Autoimmune hemolytic anemia in a patient with autosomal dominant chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis is a heterogeneous immunodeficiency syndrome characterized by recurrent candidal infections of the skin, nails, and mucous membranes. The syndrome can be associated with autoimmune conditions, especially endocrine disorders. Typically, inheritance is autosomal recessive, and abnormal T-cell-mediated immunity is thought to be the underlying deficit. We describe a 27-year-old man with chronic mucocutaneous candidiasis inherited in an autosomal dominant fashion, in whom both lymphocyte blastogenesis and delayed-type skin reactivity to Candida antigens were normal. Notable features of the case include autoimmune hemolytic anemia, probable hypoparathyroidism, and hypogonadal hypogonadism.

HLA-DQ/human CD4-restricted immune response to cockroach allergens in transgenic mice

We investigated the immune response to the German cockroach (Blattella germanica), and one of its major antigens, Blattella germanica group 5 (Bla g 5), in a double-transgenic, double-knockout mouse expressing human HLA-DQ8, HLA-DQ6 and CD4 molecules in the absence of mouse class II and mouse CD4. Transgenic mice were primed and challenged with CR extract or individual synthetic peptides representing Bla g 5. Strong T-cell responses to CR extract were detected in both HLA-DQ/hCD4+ transgenic mice. The responses were two times lower in mice expressing HLA-DQ molecule in the context of mouse CD4. Under similar treatment, no responses were found in the double-knockout Abetadegrees/mCD4degrees mice and in mice expressing human CD4 molecule alone. HLA-DQ/hCD4+ mice produced primarily interleukin (IL)-5, IL-10, and IL-13. Minimal amounts of IL-4 were detected only in HLA-DQ6/ hCD4+ mice. Interferon (IFN)-gamma production was low in both transgenic mouse, suggesting a predominantly T-helper 2 (Th2)-type response. Cockroach allergen extract immunized HLA-DQ8/hCD4+ mice recognized only one of the 20 peptides of Bla g 5 while HLA-DQ6/hCD4+ mice responded primarily to three peptides. Primed with individual peptides, both HLA-DQ/hCD4+ mice responded maximally to peptides 10 (residues 91-110) and 17 (residues 161-180). In addition, HLA-DQ6/hCD4+ mice responded to peptide 16 (residues 151-170). Thus, peptides 10 and 17 contained the major HLA-DQ-restricted hCD4+ T-cell epitopes and could be recognized by both HLA-DQ8 and HLA-DQ6 transgenic mice. Transgenic mice represent a new tool for investigating the immune responses to cockroach allergen. Our results suggest that therapeutic strategies aimed at developing antagonist peptides might be a useful treatment (immunotherapy) for allergic asthma.

Discordant and anomalous results among cytotoxicity assays: the confounding properties of eosinophil granule major basic protein on cell viability assays

When five cytotoxicity methods compared the toxicity of eosinophil granule major basic protein (MBP) and melittin to K562 and HL-60 cells, strikingly discrepant results were noted. Trypan blue staining, propidium iodide/CellTrackerGreen staining and incorporation of 14C-leucine assays indicated MBP damages > 75% of cells by 1 h. In contrast, 51Cr and lactic dehydrogenase (LDH) release assays indicated MBP damages most cells only at 20 h. All methods indicated melittin damages nearly all cells by 1 h. Further studies showed that without cell transfer, dye staining methods indicated MBP produces < 10% cytotoxicity after 4 h. A modified 14C-leucine assay, employing sodium dodecyl sulfate solubilization and trichloroacetic acid precipitation, showed lower cytotoxicity, 48%, at 4 h. Modified 51Cr and LDH assays showed increased cytotoxicities at 4 h, 34% and 58%, respectively. Overall, MBP's ability to cause molecular and cellular adhesion systematically confounds standard cytotoxicity measurements. However, the modified 14C-leucine assay provides a valid measure of MBP's cytotoxicity and may be useful for analyses of 'sticky' cytotoxins.

Eosinophil viability during immunoglobulin-induced degranulation

Eosinophil adhesion and degranulation appear to be associated with cell death. Eosinophils bound avidly and degranulated with secretory immunoglobulin A (sIgA)- and IgG-coupled Sepharose 4B beads but bound poorly and did not degranulate with ovalbumin beads. Through the use of dye staining, we found that about 50% of the bound eosinophils were dead by 4 h, regardless of the protein coating. Colchicine and reduced calcium concentration inhibited binding to beads and eosinophil degranulation in a concentration-dependent manner but did not decrease the percentages of dead bound eosinophils. Electron microscopy showed that eosinophils bound to and spread over bead surfaces. Typical granule exocytosis with release of membrane-free granules occurred in about 20% of bound eosinophils. Eosinophil degeneration and lysis with release of membrane-coated granules occurred in about 50% of bound eosinophils; often only membrane-bound granules were present. Therefore, bound eosinophils degranulate both by classical exocytosis and by release after cytolytic degeneration. By increasing the numbers of bound cells, both IgG and sIgA increase the numbers of dying cells.