Histamine-releasing Activity Research Articles

Effective in vitro evaluation of the risk of histamine release related to valemetostat tosylate using MRGPRX2-expressing cells.

Mas-related G-protein-coupled receptor X2 (MRGPRX2), expressed on mast cells, is associated with drug-induced pseudo-allergic reactions. Although it is well known that there are differences of sensitivity between species in the pseudo-allergic reactions, no platform for evaluating a human risk of the pseudo-allergic reactions observed in nonclinical studies has been established. Valemetostat tosylate, developed as an anti-cancer drug, induced histamine release in a nonclinical study with dogs. The purpose of the current study was to identify the mechanism and assess the human risk of valemetostat-tosylate-induced histamine release using dog and human MRGPRX2-expressing cells. In an experiment with human or dog MRGPRX2-expressing cells, valemetostat tosylate caused activation of human and dog MRGPRX2. Importantly, the EC50 for dog MRGPRX2 was consistent with the Cmax value at which histamine release was observed in dogs. Furthermore, the EC50 for human MRGPRX2 was ca. 27-fold higher than that for dog MRGPRX2, indicating a species difference in histamine-releasing activity. In a clinical trial, histamine release was not observed in patients receiving valemetostat tosylate. In conclusion, an in vitro assay using human and animal MRGPRX2-expressing cells would be an effective platform to investigate the mechanism and predict the human risk of histamine release observed in nonclinical studies.

Ameliorative Effect of a Neoteric Regimen of Catechin plus Cetirizine on Ovalbumin-Induced Allergic Rhinitis in Rats.

Allergic rhinitis (AR) affects 20–50% of the global population. Available treatments are limited by their adverse effects. We investigated the anti-allergic effects of catechin alone and combined with cetirizine against ovalbumin-induced AR. Rats were sensitized with ovalbumin and received catechin (14 days) and then challenged with aerosolized ovalbumin (1%) to determine AR clinical scores. Histamine, histamine release, and histidine decarboxylase (HDC) activity were determined in blood, peritoneal mast cells, and stomachs, respectively. Vascular permeability and safety were assessed using Evans blue leakage and barbiturate-induced sleeping-time assays, respectively. Catechin and cetirizine binding with HDC was investigated by docking and binding energy analyses. The clinical scores of the combination regimen were superior to either drug alone. All treatments reduced vascular leakage, with no effect on barbiturate-induced sleeping time. Only the catechin-treated rats showed reduced histamine levels and HDC activity. Docking studies revealed that catechin has a 1.34-fold higher extra-precision docking score than L-histidine. The binding energy scores for catechin-HDC, L-histidine-HDC, and histamine-HDC were −50.86, −37.64, and −32.27 kcal/mol, respectively. The binding pattern of catechin was comparable to the standard HDC inhibitor, histidine methyl ester, but with higher binding free energy. Catechin binds the catalytic residue S354, unlike cetirizine. The anti-allergic effects of catechin can be explained by HDC inhibition and possible antihistaminic activity.

Comprehensive Analysis and Biological Characterization of Venom Components from Solitary Scoliid Wasp Campsomeriella annulata annulata.

Venoms of solitary wasps are utilized for prey capture (insects and spiders), paralyzing them with a stinger injection to be offered as food for their larvae. Thus, the identification and characterization of the components of solitary wasp venoms can have biotechnological application. In the present study, the venom components profile of a solitary scoliid wasp, Campsomeriella annulata annulata, was investigated through a comprehensive analysis using LC-MS and -MS/MS. Online mass fingerprinting revealed that the venom extract contains 138 components, and MS/MS analysis identified 44 complete sequences of the peptide components. The peptides are broadly divided into two classes: bradykinin-related peptides, and linear α-helical peptides. Among the components of the first class, the two main peptides, α-campsomerin (PRLRRLTGLSPLR) and β-campsomerin (PRLRRLTGLSPLRAP), had their biological activities evaluated. Both peptides had no effects on metallopeptidases [human neprilysin (NEP) and angiotensin-converting enzyme (ACE)] and acetylcholinesterase (AChE), and had no cytotoxic effects. Studies with PC12 neuronal cells showed that only α-campsomerin was able to enhance cell viability, while β-campsomerin had no effect. It is noteworthy that the only difference between the primary structures from these peptides is the presence of the AP extension at the C-terminus of β-campsomerin, compared to α-campsomerin. Among the linear α-helical peptides, annulatin (ISEALKSIIVG-NH2) was evaluated for its biological activities. Annulatin showed histamine releasing activity from mast cells and low hemolytic activity, but no antimicrobial activities against all microbes tested were observed. Thus, in addition to providing unprecedented information on the whole components, the three peptides selected for the study suggest that molecules present in solitary scoliid wasp venoms may have interesting biological activities.

A case report on succinylcholine hypersensitivity presenting as severe bronchospasm

Succinylcholine is a depolarizing neuromuscular blocking agent, useful as an adjunct to general anaesthesia. Hypersensitivity to succinylcholine might lead to flushing, skin rash, bronchospasm, and shock. However, incidence of bronchospasm is less common in man. A 26 years old female patient at our setup, while undergoing dilatation and evacuation procedure, was administered with Injection Scoline (Succinylcholine) 50 milligrams intravenous. Within a minute, patient was gasping and underwent severe bronchospasms. Her SpO2 was 94% along with development of crepitation with tachypnoea and spasms (>30 respirations/minute). She was immediately resuscitated and intubated by the attending anaesthetist, treated for bronchospasm as well as shifted on ventilator. Within few hours, she was taken off the ventilator and extubated. She was stable then and discharged after two days. Hypersensitivity to NMBAs low incidence of 1 in 6000 - 20,000. NMBAs have a direct effect on mast cells thereby causing hypersensitivity reactions. Succinylcholine is considered to have 1% histamine releasing activity of tubocurarine, producing serious hypersensitivity reactions. This histamine released acts on the effector end-receptors in bronchial wall, leading to bronchoconstriction and sometimes a full-blown spasm. If timely management failed, it can result into an anaesthetic disaster. Rechallenge with succinylcholine was avoided due to possibility of fatal consequences. According to WHO UMC criteria & Naranjo Scale for causality assessment, causality was termed as “Probable”. Keywords: Bronchospasm, Hypersensitivity, Life-threatening, Neuromuscular Blocking Agent (NMBA), Suspected adverse drug reaction.

Autologous serum skin test as an indicator of chronic urticaria in comparison with serum IgE level at a tertiary care center in North-Eastern India

Introduction: Chronic urticaria (CU) is as a distressing condition that may present with short-lived itchy weal, angioedema, or both. Autologous serum skin test (ASST) is a simple in vivo clinical test for the detection of basophil histamine-releasing activity. ASST is a very simple, quick test which consists of intradermal injection of patient's own serum into the volar aspect of forearm. A significant association between increased total IgE and CU severity was found. The present study was done to find out the clinical profiles of CU in MGM Medical College and LSK Hospital. ASST was done, and serum IgE level in patients with chronic spontaneous urticaria estimated and to give an insight on degree of serum IgE level with ASST positivity.Materials and Methods: This was a cross-sectional study where a total of 100 patients were enrolled. Detailed history, physical examination, and routine investigations were recorded for all patients. ASST and serum IgE were done in all patients.Results: Of total of 100 patients enrolled in the study, ASST positive group consists of 29 patients and ASST negative group consists of 71 patients. A total of 46 patients got raised IgE, and the rest 54 had normal IgE level; out of IgE positive, 34 patients were ASST negative, and rest 12 patients were ASST positive. Majority of ASST positive patients had normal serum IgE level (n = 17). Nine and three patient's IgE level were in the range of 200–300 and 300–400 IU/ml, respectively.Conclusion: The ASST is a simple, practicable in vivo intradermal test for the detection of autoimmune urticaria. There was significant association seen with the duration of disease and ASST positivity. The present study did not show any association between increased serum IgE and ASST positivity.

Differentiation between control subjects and patients with chronic spontaneous urticaria based on the ability of anti-IgE autoantibodies (AAbs) to induce FcεRI crosslinking, as compared to anti-FcεRIα AAbs

BackgroundThe reported prevalences of IgG autoantibodies (AAbs) to FcεRIα and IgE in sera from patients with chronic spontaneous urticaria (CSU) have varied, and these AAbs are also often observed in healthy control subjects. Regarding the histamine release activity of purified IgG from patients with CSU, the number of examined patients has been small. Thus, we sought to determine the prevalence and FcεRI crosslinking ability of these AAbs in a large number of patients with CSU and non-atopic control (NC) subjects. MethodsWe compared the concentrations of anti-IgE and anti-FcεRIα AAbs and the abilities of these AAbs to cause FcεRI aggregation in patients with CSU (n = 134) and NC subjects (n = 55) using ELISA and an in vitro elicitation test, respectively. ResultsThe concentration of anti-IgE AAbs was significantly different between the NC subjects and the CSU patients (P < 0.0001, cutoff value: 0.558 μg/mL), whereas the concentration of anti-FcεRIα AAbs was not. A significant difference in the duration of illness was noted between patients with lower and those with higher concentrations of anti-IgE AAbs relative to the cutoff value. The abilities of anti-IgE AAbs, but not anti-FcεRIα AAbs, to induce FcεRI crosslinking were significantly higher in CSU patients than in NC subjects (P = 0.0106). ConclusionsIn the Japanese population of CSU patients studied, the ability of the anti-IgE AAbs to induce FcεRI crosslinking differed significantly between NC subjects and CSU patients, suggesting the involvement of anti-IgE AAbs in the pathogenesis of CSU in the Japanese population.

Eremomycin pyrrolidide: a novel semisynthetic glycopeptide with improved chemotherapeutic properties.

PurposeDevelopment of new semisynthetic glycopeptides with improved antibacterial efficacy and reduced pseudoallergic reactions.MethodsSemisynthetic glycopeptides 3–6 were synthesized from vancomycin (1) or eremomycin (2) by the condensation with pyrrolidine or piperidine. The minimum inhibitory concentration (MIC) for the new derivatives was measured by the broth micro-dilution method on a panel of clinical isolates of Staphylococcus and Enterococcus. Acute toxicity (50% lethal dose, maximum tolerated doses), antibacterial efficacy on model of systemic bacterial infection with S. aureus and pseudoallergic inflammatory reaction (on concanavalin A) of eremomycin pyrrolidide (5) were evaluated in mice according to standard procedures.ResultsThe eremomycin pyrrolidide (5) was the most active compound and showed a high activity against Gram-positive bacteria: vancomycin-susceptible staphylococci and enterococci (minimum inhibitory concentrations [MICs] 0.13–0.25 mg/L), as well as vancomycin-intermediate resistant Staphylococcus aureus (MICs 1 mg/L). Antimicrobial susceptibility tested on a panel of 676 isolates showed that 5 had similar activity for the genera Staphylococcus and Enterococcus with MIC90=0.5 mg/L, while vancomycin had MIC90=1–2 mg/L. The number of resistant strains of Enterococcus faecium (vancomycin-resistant enterococci) (MIC =64 mg/L) with this value was 7 (8%) for vancomycin (1) and 0 for the compound 5. In vivo comparative studies in a mouse model of systemic bacterial infection with S. aureus demonstrated that the efficacy of 5 was notably higher than that of the original antibiotics 1 and 2. In contrast to 1, compound 5 did not induce pseudoallergic inflammatory reaction (on concanavalin A).ConclusionThe new semisynthetic derivative eremomycin pyrrolidide (5) has high activity against staphylococci and enterococci including vancomycin-resistant strains. Compound 5 has a higher efficacy in a model of staphylococcal sepsis than vancomycin (1) or eremomycin (2). In striking contrast to natural antibiotics, the novel derivative 5 does not induce a pseudoallergic inflammatory reaction to concanavalin A and therefore has no histamine release activity. These results indicate the advantages of a new semisynthetic glycopeptide antibiotic eremomycin pyrrolidide (5) which may be a prospective antimicrobial agent for further pre-clinical and clinical evaluations.

Conversion of Curcumin into Heterocyclic Compounds as Potent Anti-diabetic and Anti-histamine Agents.

Potential biologically active derivatives of the curcumin were prepared by the cyclocondensation reaction cyclohexanone 2, imino pyrimidine 3, pyrmidinones 4, thiopyrimidine 6 and pyranone 5, 7 when treated with acetylacetone, guanidine, ureaethylcyanoacetate, thiourea and ethylacetoacetate, respectively. The structures of compounds (2-7) were elucidated by means of microanalysis as well as spectral measurements such as IR, 1H-NMR, MS. The anti-diabetic potential of curcumin derivatives were evaluated by assessing amylase inhibition assay, also inhibition of histamine release activity of curcumin derivatives were assessed by U937 human monocytes. The results for amylase inhibition activity revels that the curcumin inhibits α-amylase in a concentration dependent manner. Compounds 4 and 5 exhibited significant inhibitory activity against amylase enzyme and was comparable with that of acrabose. Also, compounds 5, 6 and 7 exhibited significant inhibitory activity against histamine. Our results concluded that curcumin pyrmidinones and pyranone derivatives have highly effects as anti-diabetic and anti-histamine activities.

A cross-sectional study on autologous: serum skin test in chronic urticaria in a tertiary care centre

&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Background:&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-US"&gt; Urticaria persisting daily for more than six weeks is termed as chronic urticaria. A significant number of them have an autoimmune basis, where ASST is &lt;/span&gt;used for detection of chronic autoimmune urticaria (CAU). &lt;span lang="EN-US"&gt;The aim and objective of the study was &lt;/span&gt;to determine the frequency of autoimmunity with ASST in chronic urticaria patients.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Methods:&lt;/span&gt;&lt;/strong&gt;This was a hospital based cross sectional study, 100 patients with chronic urticaria fulfilling the inclusion and exclusion criteria were enrolled in the study. Detailed history, physical examination and routine investigations were recorded and ASST was done for all patients.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Results:&lt;/span&gt;&lt;/strong&gt;Thirty seven (37%) out of 100 CU patients were ASST positive. Statistical analysis of the clinical variables did not show significant difference between ASST positive and negative patients except for dermographism and mean duration of the disease.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Conclusions:&lt;/span&gt;&lt;/strong&gt;ASST is a simple &lt;em&gt;invivo&lt;/em&gt; clinical test for detection of basophil histamine releasing activity. Diagnosing CAU is important as these patients may need high doses of anti-histamines, systemic corticosteroids and/or immunomodulatory drugs. Autologous serum therapy itself has a therapeutic role in treatment of CAU patients.&lt;/p&gt;

Isolation of biologically active peptides from the venom of Japanese carpenter bee, Xylocopa appendiculata

BackgroundMass spectrometry-guided venom peptide profiling is a powerful tool to explore novel substances from venomous animals in a highly sensitive manner. In this study, this peptide profiling approach is successfully applied to explore the venom peptides of a Japanese solitary carpenter bee, Xylocopa appendiculata (Hymenoptera: Apoidea: Apidae: Anthophila: Xylocopinae: Xylocopini). Although interesting biological effects of the crude venom of carpenter bees have been reported, the structure and biological function of the venom peptides have not been elucidated yet.MethodsThe venom peptide profiling of the crude venom of X. appendiculata was performed by matrix-assisted laser desorption/ionization-time of flight mass spectroscopy. The venom was purified by a reverse-phase HPLC. The purified peptides were subjected to the Edman degradation, MS/MS analysis, and/or molecular cloning methods for peptide sequencing. Biological and functional characterization was performed by circular dichroism analysis, liposome leakage assay, and antimicrobial, histamine releasing and hemolytic activity tests.ResultsThree novel peptides with m/z 16508, 1939.3, and 1900.3 were isolated from the venom of X. appendiculata. The peptide with m/z 16508 was characterized as a secretory phospholipase A2 (PLA2) homolog in which the characteristic cysteine residues as well as the active site residues found in bee PLA2s are highly conserved. Two novel peptides with m/z 1939.3 and m/z 1900.3 were named as Xac-1 and Xac-2, respectively. These peptides are found to be amphiphilic and displayed antimicrobial and hemolytic activities. The potency was almost the same as that of mastoparan isolated from the wasp venom.ConclusionWe found three novel biologically active peptides in the venom of X. appendiculata and analyzed their molecular functions, and compared their sequential homology to discuss their molecular diversity. Highly sensitive mass analysis plays an important role in this study.

Serum Clusterin as a Prognostic Marker of Chronic Spontaneous Urticaria.

A substantial proportion of patients with chronic spontaneous urticaria (CSU) are refractory to antihistamines. However, identifying the subpopulation whose urticaria is not completely controlled by antihistamines remains difficult. The response of autologous serum skin test (ASST), a clinical test for the detection of basophil histamine-releasing activity upon autoantibodies or autoreactive stimulation, has been suggested as a potential predictor in the control of urticaria. We sought to identify proteins that were differentially expressed in the sera of patients with positive and negative ASST results and to investigate their association with urticaria control.Proteomics analysis was performed using sera from 3 CSU patients with positive ASST results compared with those showing negative ASST results. Seven upregulated and 5 downregulated proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the ASST-positive group compared with the ASST-negative group.Proteins that were differentially expressed according to the ASST results in CSU patients were classified into 6 groups: apolipoproteins, glycoproteins, modified albumin, haptoglobulin, plectin, and others. Among these, apolipoprotein J or clusterin was validated using an enzyme-linked immunosorbent assay. Clusterin levels in 69 ASST-positive patients were significantly higher than those in 69 ASST-negative patients and in 86 healthy controls (231.2 ± 44.0 vs 210.2 ± 36.1 vs 118.7 ± 71.9 μg/mL, P < 0.001). Furthermore, clusterin levels differed significantly between patients with responsive and refractory responses to antihistamine treatment within 3 months (231.0 ± 39.1 vs 205.1 ± 40.4 μg/mL, P < 0.001). ASST results and serum clusterin levels can predict 92.7% of CSU patients whose urticaria would be refractory to antihistamines. Serum clusterin can be a prognostic marker to determine the responsiveness to antihistamine treatment in patients with CSU.

Transglutaminase II/MicroRNA-218/-181a Loop Regulates Positive Feedback Relationship between Allergic Inflammation and Tumor Metastasis

The molecular mechanism of transglutaminase II (TGaseII)-mediated allergic inflammation remains largely unknown. TGaseII, induced by antigen stimulation, showed an interaction and co-localization with FcϵRI. TGaseII was necessary for in vivo allergic inflammation, such as triphasic cutaneous reaction, passive cutaneous anaphylaxis, and passive systemic anaphylaxis. TGaseII was necessary for the enhanced metastatic potential of B16F1 melanoma cells by passive systemic anaphylaxis. TGaseII was shown to be a secreted protein. Recombinant TGaseII protein increased the histamine release and β-hexosaminidase activity, and enhanced the metastatic potential of B16F1 mouse melanoma cells. Recombinant TGaseII protein induced the activation of EGF receptor and an interaction between EGF receptor and FcϵRI. Recombinant TGaseII protein displayed angiogenic potential accompanied by allergic inflammation. R2 peptide, an inhibitor of TGaseII, exerted negative effects on in vitro and in vivo allergic inflammation by regulating the expression of TGaseII and FcϵRI signaling. MicroRNA (miR)-218 and miR-181a, decreased during allergic inflammation, were predicted as negative regulators of TGaseII by microRNA array and TargetScan analysis. miR-218 and miR-181a formed a negative feedback loop with TGaseII and regulated the in vitro and in vivo allergic inflammation. TGaseII was necessary for the interaction between mast cells and macrophages during allergic inflammation. Mast cells and macrophages, activated during allergic inflammation, were responsible for the enhanced metastatic potential of tumor cells that are accompanied by allergic inflammation. In conclusion, the TGaseII/miR-218/-181a feedback loop can be employed for the development of anti-allergy therapeutics.

Autologous serum skin test as an indicator of chronic autoimmune urticaria in a tertiary care hospital in South India.

Background:Autologous serum skin test (ASST) is a simple in-vivo clinical test for the detection of basophil histamine releasing activity and to diagnose chronic autoimmune urticaria (CAU) among chronic spontaneous urticaria (CSU) patients. Diagnosing these patients is also important as they may need high doses of antihistamines and systemic corticosteroids during acute exacerbations.Aims and Objectives:The aim of this study is to study the prevalence of CAU among cases of CSU by using ASST.Materials and Methods:This was a cross-sectional study done among 48 patients presenting with CSU. Detailed history, physical examination and routine investigations were recorded for all patients. ASST was done on all the 48 patients.Results:Of the 48 patients included in the study, 20 patients (41.6%) were ASST positive, while the remaining 28 (58%) were ASST negative. The median duration of disease in both ASST positive and negative patients was 1 year. ASST positivity was higher (66.6%) among patients with a history of round shaped weals, though not statistically significant. ASST positivity was seen in 5 (71.4%) out of seven patients with systemic involvement, which was again not statistically significant.Conclusion:Our study did not show any significant difference between patients with and without antibodies regarding mean age and sex distribution, clinical morphology of individual weals, duration, severity, systemic symptoms, angioedema, atopy, and association with other autoimmune conditions.

Evaluation of CCR3 as a Basophil Activation Marker

Recent reports have provided conflicting evidence on the stability of CCR3 expression on the surface of basophils. Hence we wanted to independently evaluate the diagnostic usefulness of CCR3 as a surrogate marker of basophil activation and function. We examined the correlative relationship between CCR3 expression on the surface of donor basophils and histamine release after donor basophils were treated with agonistic antibodies directed against the high-affinity IgE-Fc receptor and serum samples from 80 individuals displaying symptoms of chronic urticaria (CU). We observed that CCR3 was significantly downregulated on donor basophils treated with the agonistic antibody and CU-patient serum that demonstrated positive "histamine-releasing activity" (HRA scores >10). However, CCR3 downregulation was also observed on donor basophils incubated with more than 40% of CU-patient serum samples with HRA scores less than or equal to 10. Overall our data show that CCR3 demonstrates adequate sensitivity (83%) but weak specificity (59%) in its ability to reliably identify histamine-releasing activated basophils.

Fungal protein MGL_1304 in sweat is an allergen for atopic dermatitis patients

Sweat is a major aggravating factor of atopic dermatitis (AD) and approximately 80% of patients with AD show type I hypersensitivity against sweat. To identify and characterize an antigen in sweat that induces histamine release from basophils of patients with AD. Basophil histamine-releasing activity in sweat was purified by a combination of chromatographies, and proteins were analyzed with mass spectrometry. Recombinant proteins of the sweat antigen were generated, and their biological characteristics were studied by immunoblots, histamine release tests, and neutralization assays. We identified a fungal protein, MGL_1304, derived from Malassezia globosa (M globosa) in the purified sweat antigen. Recombinant MGL_1304 induced histamine release from basophils of most of the patients with AD, in accordance with the semi-purified sweat antigen. Moreover, recombinant MGL_1304 abolished the binding of serum IgE of patients with AD to the semi-purified sweat antigen, or vice versa in immunoblot analysis, and attenuated the sensitization of RBL-48 mast cells expressing human FcɛRI by serum IgE. Studies of truncated mutants of MGL_1304 indicated that IgE of patients with AD recognized the conformational structure of MGL_1304 rather than short peptide sequences. Western blot analysis of the whole lysate, the culture supernatant of M globosa, and the semi-purified sweat antigen showed that MGL_1304 was produced as a minor immunological antigen of M globosa with posttranslational modification, cleaved, and secreted as a 17-kDa major histamine-releasing sweat antigen. MGL_1304 is a major allergen in human sweat and could cause type I allergy in patients with AD.

Dimerization of TCTP and its clinical implications for allergy

Following the detection of histamine-releasing activity (HRA) in the supernatants of peripheral blood mononuclear cell cultures, research efforts were directed at characterizing the source of this activity, mostly focusing, on IgE-dependent histamine-releasing factors (HRFs). HRF is now variously called translationally controlled tumor protein (TCTP), p21, p23, and fortilin. TCTP exhibits cytokine-like functions including release of histamine, induction of TH2 cytokines and chemoattractants, augmentation of B cell proliferation, and immunoglobulin production during late phase allergic inflammation. Because of its association with the allergic status of patients, TCTP emerged as a potential key agent in the modulation of allergic diseases. Several lines of evidence suggest that TCTP exhibits its cytokine-like functions only after it is modified by the proteases, altered oxidant-antioxidant balance and immunoglobulin E, present in the inflamed sites. This review will try to show that dimerization is the critical modification of TCTP if not the only modification, responsible for its cytokine-like activity causing allergic diseases.

The influence of cholinergic agents on histamine release from HMC-1 human mast cell line stimulated with IgG, C-reactive protein and compound 48/80

AimsThe aim of this work is to study the role of acetylcholine (ACh) receptors (AChRs) in the regulation of FcγR activity in human mast cells (MC) activated by aggregated IgG (aIgG) and CRP. MC, the key regulators at the interface of innate and acquired immunity, have abundant Fc receptors for IgG (FcγRII) which indicate the role of their ligands, IgG and C-reactive protein (CRP), in regulating MC activity. Cholinergic control of FcγR-dependent MC functions is poorly defined. Main methodsHMC-1 culture of human MC; cell incubations with cholinergic drugs and FcγR ligands such as heat aggregated human IgG or purified human CRP; compound 48/80, a known histamine liberator employing G protein-coupled receptors, was used as a positive control of MC degranulation; assessment of histamine release. Key findingsBoth nAChR and mAChR antagonists (hexamethonium and methacine, respectively), per se, elevated histamine-releasing activity of the HMC-1 and suppressed the MC responses to most of investigated activators (carbachol, compound 48/80, and to a lesser extent aIgG). Two blockers together should be applied to aIgG-stimulated cells in order to obtain appreciable suppression of histamine release. The FcγR-mediated HMC-1 cell response to CRP was the least sensitive to attenuation by ACh signaling. SignificanceThe data obtained suggest the involvement of ACh in the functioning of other receptor systems. Our results indicate that AChRs are closely associated with G protein-coupled receptor-induced reactions of MC and optionally with FcγR-dependent functions. ConclusionThe data presented demonstrate that AChRs and endogenous ACh are involved in regulating mast cell degranulation and histamine release by affecting the functions of receptors to compound 48/80 and, less, FcγRs.

Mizoribine treatment for antihistamine-resistant chronic autoimmune urticaria

Chronic autoimmune urticaria is routinely diagnosed using an autologous serum skin test. Mizoribine is a newly developed immunosuppressive agent that has low toxicity. The pharmacological effects of mizoribine are similar to those of another purine biosynthesis inhibitor, mycophenolate mofetil. A 57-year-old woman presented with recurrent wheals and was insufficiently managed with administration of antihistamines, antileukotrienes, oral corticosteroids, and cyclosporine. She was positive in the autologous serum skin test. Oral mizoribine therapy was started as a combination therapy with prednisolone. The patient achieved a dramatic improvement in symptoms and complete resolution of the urticaria a few days after adding mizoribine to her treatment. The prednisolone was tapered after the start of mizoribine treatment. Her symptoms did not flare up, and no side effects were observed. In vitro basophil histamine release assays suggested that she might have anti-IgE autoantibody-type histamine release activity. We believe that mizoribine has a therapeutic role in some patients with chronic autoimmune urticaria and may be useful for treatment of cases not responsive to classical therapy. We suggest that mizoribine might help to reduce anti-IgE autoantibody acting on the surface of basophils in chronic autoimmune urticaria.

Histamine release-neutralization assay for sera of patients with atopic dermatitis and/or cholinergic urticaria is useful to screen type I hypersensitivity against sweat antigens

We previously reported that about 80% of patients with atopic dermatitis and 60% with cholinergic urticaria revealed type I allergy against sweat, by means of skin test against autologous sweat and/or histamine-release test for peripheral blood basophils with semi-purified sweat antigen. In this study, we developed an assay for sera to neutralize histamine-releasing activity of semi-purified sweat antigen. The semi-purified sweat antigen was pre-incubated with serially diluted sera for 30min at 37°C and was subjected to histamine-release activity. Histamine release-neutralization (HRN) activities were calculated by measuring the amount of histamine release from basophils in the presence or absence of semi-purified sweat antigen. Of 62 subjects, 39 showed positive histamine release (≥5%) from their basophils in response to semi-purified sweat antigen, and sera of 34 out of 39 subjects (87.2%) were also positive in HRN activity (≥10%). The specificity of the HRN assay was 0.522. Moreover, HRN activities in sera were largely correlated with degrees of histamine release from peripheral blood basophils of the same donors in response to sweat antigen. To identify the substance that neutralizes histamine-release activity, we removed IgE and IgG from the sera of HRN (+) subjects by column chromatography. The HRN activities in 30 out of 42 sera were largely reduced by the removal of IgG. On the other hand, sera of four subjects lost HRN activity by the removal of IgE, suggesting that the majority of HRN (+) subjects have serum IgG against the sweat antigen as well as IgE bound to peripheral basophils. Thus, the HRN assay maybe useful for the screening of type I allergy against sweat antigen.

Development and preliminary clinical evaluation of a peptide immunotherapy vaccine for cat allergy

Allergic sensitization to cat allergens is common and represents a major risk factor for asthma. Specific immunotherapy (SIT) is effective but cumbersome and associated with IgE-dependent adverse events. Immunotherapy targeting allergen-specific T cells, with synthetic peptides representing T-cell epitopes, might improve safety and reduce the duration of treatment. We sought to define major T-cell epitopes of Fel d 1 for peptide immunotherapy, generate a peptide vaccine, and evaluate its safety and tolerability in subjects with cat allergy. We determined the binding affinities of Fel d 1 peptides for 10 commonly expressed HLA-DR molecules. Functionally immunodominant peptides were identified by means of proliferation and cytokine secretion. Histamine-releasing activity was assessed, and a peptide vaccine was formulated. Safety and tolerability were evaluated in a dose-ranging phase IIa clinical trial. MHC-binding sequences were identified throughout Fel d 1. Some regions contained multiple overlapping T-cell epitopes that bound multiple MHC molecules. Immunodominant sequences were identified on the basis of proliferative and cytokine (IFN-γ, IL-10, and IL-13) responses. Cat allergen extract, but not peptides, induced histamine release in blood basophils. A single administration of peptide vaccine was safe and well tolerated. The dose of vaccine resulting in the greatest inhibition of the late-phase skin response to intradermal whole allergen challenge was 3 nmol. Fel d 1 contains multiple overlapping MHC-binding motifs. A peptide vaccine comprising the immunodominant regions of the allergen was safe and well tolerated when given to subjects with cat allergy as a single dose. The dose of vaccine resulting in the greatest reduction in late-phase skin response was defined for future clinical development.