Citations

Abstract Adenosine 5′-triphosphate (ATP) is released from the cytoplasm under physiologic and pathophysiologic conditions and enters the extracellular space, where it acts on a group of recently cloned cell-surface receptors termed P2-purinoceptors (subtypes P2X and P2Y). We examined the effects of extracellular ATP, uridine triphosphate (UTP), the stable ATP analogues α,βmethylene-ATP (α,βmATP), β,γmethylene-ATP (β,γmATP), and 2-methylthio-ATP (2mSATP), and adenosine (10−6–10−3 M) on histamine release from human lung mast cells (HLMC) induced by anti-IgE and the calcium ionophore A23187. None of the nucleotides or adenosine directly induced histamine release. Adenosine exhibited a bimodal effect, enhancing histamine release at 10−6 to 10−4 M (P > 0.05, NS) and inhibiting it at 10−3 M (P < 0.05). ATP (10−4 M) enhanced anti-IgE–induced histamine release (10.9 ± 2.7% to 19.2 ± 2.9%, n = 20, P < 0.01), but not ionophore A23187-induced histamine release (n = 10). The adenine nucleotides consistently enhanced anti-IgE–induced histamine release; the rank order for this action was: ATP > 2mSATP > α,βmATP > β,γmATP, suggesting mediation by a P2Y-purinoceptor subtype. The selective P2X purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid failed to influence the effect of ATP, further supporting P2Y-purinoceptor mediation of anti-IgE–induced histamine release. UTP, an agonist at P2Y-purinoceptors, also significantly enhanced anti-IgE–induced histamine release. Application of the reverse transcription–polymerase chain reaction indicated that HLMC constitutively express the messenger RNAs encoding the P2Y1- and P2Y2-purinoceptor subtypes, and not that encoding the P2X7-purinoceptor (i.e., P2Z), a subtype implicated in ATP-induced histamine release in rodent peritoneal mast cells. The data produced in the study suggest that ATP plays an important modulatory role in histamine release from HLMC, and that it may therefore be mechanistically involved in human allergic/asthmatic reactions.

“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. Am. J. Hematol. 88:406–408, 2013. © 2013 Wiley Periodicals, Inc.

Aim: To investigate the relationship between clinical mast cell activity and primary headache syndromes. Methods: We surveyed individuals with systemic mastocytosis, an uncommon disorder associated with increased mast cell activity. Diagnoses of primary headache syndromes in addition to the relationship of headache and symptoms of mastocytosis were ascertained. Results: A response rate of 64/148 (43.2%) was achieved. Headache diagnoses in our respondents (n = 64) were largely migraine (37.5%) and tension-type headaches (17.2%). Typical aura with and without migraine headache was highly represented in our patient population (n = 25, 39%). Three individuals met criteria for primary cough headache (4.7%). Symptoms reflective of mast cell activity were significantly greater in individuals reporting headaches. Patients experiencing headache concurrently with mastocytosis flairs were more likely to be male (p = 0.002), have histaminergic symptoms, such as itching (p = 0.02) and runny nose (p = 0.03), and have unilateral cranial autonomic features (p = 0.04). However, using standardized International Headache Society criteria, we did not identify individuals with cluster headache or other trigeminal autonomic cephalalgias in this population. Conclusions: Our observational survey-based data supports a clinical relationship between mast cell activity and primary headache syndromes. Generalizability of our results is limited by the low response rate and possible tertiary referral bias.

Background— Clopidogrel and ticlopidine are structurally very similar. In patients with an allergic or hematologic adverse reaction to either one of these drugs, the likelihood that an allergic or hematologic adverse effect will develop to the other is unknown. It is also unknown whether a reaction to the second thienopyridine is likely to be life threatening. Methods and Results— Medical records from 2 academic institutions were reviewed to identify patients who had an allergic or hematologic adverse reaction to either of the 2 currently commercially available thienopyridines and who were subsequently prescribed the other thienopyridine. Patient demographics, details of the adverse reactions, and subsequent clinical course were reviewed. A total of 76 patients were identified with an allergic or hematologic adverse reaction to clopidogrel or ticlopidine who had also received the other thienopyridine. Fourteen (27%; 95% CI, 16 to 41) patients who had an allergic or hematologic adverse reactions to clopidogrel had a similar reaction to ticlopidine; none developed a life-threatening reaction. The most common reaction was a rash (93%). Conclusions— In patients with an allergic or hematologic adverse reaction to one thienopyridine, there seems to be an increased frequency of such reactions to the other thienopyridine. However, no patient had a life-threatening reaction after exposure to the alternative thienopyridine.

Abstract Clinical phenotype in systemic mastocytosis (SM) is markedly variable, which complicates prognostication and decision making regarding the choice and timing of therapy. In a retrospective study of 342 consecutive adult patients with SM seen at the Mayo Clinic between 1976 and 2007, disease subdesignation according to the World Health Organization (WHO) proposal was indolent (ISM) in 159 (46%), with associated clonal hematologic non–mast cell lineage disease (SM-AHNMD) in 138 (40%), aggressive (ASM) in 41 (12%), and mast cell leukemia in 4 (1%). KITD816V was detected in bone marrow–derived DNA by allele-specific polymerase chain reaction (PCR) in 68% of 165 patients evaluated (ISM, 78%; ASM, 82%; SM-AHNMD, 60%; P = .03); JAK2V617F was detected in 4%, all in SM-AHNMD. Compared with those with nonindolent SM, life expectancy in ISM was superior and not significantly different from that of the age- and sex-matched US population. In addition, multivariable analysis identified advanced age, weight loss, anemia, thrombocytopenia, hypoalbuminemia, and excess bone marrow blasts as independent adverse prognostic factors for survival. The current study validates the prognostic relevance of the WHO subclassification of SM and provides additional information of value in terms of both risk stratification and interpretation of clinical presentation and laboratory results.

ABSTRACTClostridium difficiletoxins A and B (TcdA and TcdB) are the causative agents of antibiotic-associated pseudomembranous colitis. Mucosal mast cells play a crucial role in the inflammatory processes underlying this disease. We studied the direct effects of TcdA and TcdB on the human mast cell line HMC-1 with respect to degranulation, cytokine release, and the activation of proinflammatory signal pathways. TcdA and TcdB inactivate Rho GTPases, the master regulators of the actin cytoskeleton. The inactivation of Rho GTPases induced a reorganization of the actin cytoskeleton accompanied by morphological changes of cells. The TcdB-induced reorganization of the actin cytoskeleton in HMC-1 cells reduced the number of electron-dense mast cell-specific granules. Accordingly, TcdB induced the release of hexosaminidase, a marker for degranulation, in HMC-1 cells. The actin rearrangement was found to be responsible for degranulation since latrunculin B induced a comparable hexosaminidase release. In addition, TcdB as well as latrunculin B induced the activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 and also resulted in a p38 MAPK-dependent increased formation of prostaglandins D2and E2. The autocrine stimulation of HMC-1 cells by prostaglandins partially contributed to the degranulation. Interestingly, TcdB-treated HMC-1 cells, but not latrunculin B-treated HMC-1 cells, showed a strong p38 MAPK-dependent increase in interleukin-8 release. Differences in the mast cell responses to TcdB and latrunculin B are probably due to the presence of functionally inactive Rho GTPases in toxin-treated cells. Thus, the HMC-1 cell line is a promising model for studying the direct effects ofC. difficiletoxins on mast cells independently of the tissue context.

Objective.Eosinophil-associated proteins, especially eosinophil-derived neurotoxin, may be important contributors to the neurologic pathology and symptoms caused byBaylisascaris procyonis infection.Methods.Two cases of severe B procyonisencephalitis with evidence of marked eosinophil degranulation in the central nervous system are presented. Serial cerebrospinal fluid (CSF) specimens were collected from each patient during the course of their illness. Antibodies against B procyonis were measured in the patients' serum and CSF. Levels of the eosinophilopoietin interleukin-5 (IL-5) and 2 important eosinophil proteins, eosinophil-derived neurotoxin and major basic protein, were assayed in the CSF.Results.Both patients had rapidly progressive central nervous system disease with evidence of eosinophilic meningoencephalitis. Both tested positive for antibodies to B procyonis in serum and CSF and had progressively worsening deep white matter changes on magnetic resonance images of the brain. CSF levels of IL-5, eosinophil-derived neurotoxin, and major basic protein were markedly elevated over controls.Conclusions.This is the first report of the measurement of IL-5, eosinophil-derived neurotoxin, and major basic protein in human CSF. In addition to traumatic damage and necrosis caused by migrating larvae, eosinophil-derived neurotoxin from associated eosinophilic inflammation may be an important contributory factor in the pathogenesis of B procyonis encephalitis. parasite, eosinophil-derived-neurotoxin, major basic protein, eosinophilia, hypereosinophilia, interleukin-5, encephalitis, child.

AbstractNeurotrophins, such as nerve growth factor (NGF) and neurotrophin-3 (NT-3), are essential for development, function, and survival of peripheral sympathetic and sensory neurons. Most eosinophilic leukocytes in the human body are localized in mucosal tissues; however, the roles of eosinophils in human diseases are not fully understood. We found that human eosinophils constitutively express messenger RNA for NGF and NT-3, synthesize and store these proteins intracellularly, and continuously replenish them. Incubation of eosinophils with a transcription inhibitor, actinomycin D, for 8 hours completely depletes intracellular NGF and NT-3. New synthesis of NGF is enhanced by Fc-receptor–mediated stimuli, such as immunoglobulin (Ig)A and IgG immune complexes; in contrast, production of NT-3 is not affected by these stimuli. Notably, supernatants of eosinophils stimulated with IgA immune complex and interleukin 5 promote neurite extension of the PC-12 pheochromocytoma cell line; this effect is abolished by pretreatment of the supernatants with anti-NGF–neutralizing antibody. By enzyme-linked immunosorbent assay, substantial amounts of NGF protein are also detected in the supernatants of stimulated eosinophils. Furthermore, in patients with seasonal allergic rhinitis, the concentrations of NGF in nasal secretions correlate with the magnitudes of eosinophilic inflammation in the airway, suggesting a potential clinical implication of eosinophil NGF. Our observations propose a new pathologic mechanism by which eosinophils may contribute to enhanced neurologic responses in patients with allergic diseases and other eosinophilic disorders. Alternatively, eosinophils may play important roles in maintenance and restoration of homeostatic functions of mucosal tissues through the pleitropic activities of NGF.