Cultured peripheral blood mast cells from chronic idiopathic urticaria patients spontaneously degranulate upon IgE sensitization: Relationship to expression of Syk and SHIP-2.

Recently, signaling changes in the FcvarepsilonRI pathway involving inositol lipid phosphatases have been identified in the basophils of chronic idiopathic urticaria (CIU) subjects. Based on the profile of basophil FcvarepsilonRI-mediated histamine degranulation, we have segregated CIU subjects into two groups, CIU Responder (CIU R) or CIU Nonresponder (CIU NR). In the present study, we compared expression of SHIP-1, SHIP-2, and Syk protein to histamine release (HR) from mast cells (MC) cultured from the peripheral blood of CIU R, CIU NR, and normal subjects. The MC of CIU R donors contained significantly increased Syk and decreased SHIP-2 as compared to CIU NR (Syk: p=0.038, SHIP-2: p=0.038) and normals (Syk: p=0.042, SHIP-2: p=0.027). Spontaneous HR from CIU donors was increased two-fold compared to normals (p=0.04). In summary, our results suggest a possible predilection for urticarial MC to spontaneously degranulate upon IgE sensitization contributing to the increased pruritus associated with CIU.

Basophil histamine release activity and disease severity in chronic idiopathic urticaria.

BACKGROUND: Altered basophil degranulation phenotypes are found in patients with chronic idiopathic urticaria (CIU). OBJECTIVE: To evaluate CIU disease severity in relation to basophil histamine release (HR) characteristics. METHODS: Patients with CIU were recruited from allergy and dermatology clinics. Patients with recent use of systemic corticosteroids or immunosuppressants were excluded. Patients completed disease severity surveys and had blood basophils isolated and stimulated for HR using polyclonal goat anti-human IgE and N-formyl-met-leu-phe. The HR was measured using automated fluorometry. Multivariate linear regression analyses were used to investigate relationships between HR data and CIU disease measures. RESULTS: Fifty patients completed surveys, of which 34 were further categorized into 2 subgroups based on basophil HR response to anti-IgE stimulation: responders (> or = 10% HR) and nonresponders (< 10% HR). Responders and nonresponders reported similar use of oral corticosteroids, work absences, and quality-of-life impairment but differed in their patterns of medications used for CIU. Basophil responders had a trend of higher use of the emergency department for CIU management. Multivariate regression revealed that patients with the basophil responder phenotype experienced significantly higher current itch scores (P = .02) compared with nonresponders. CONCLUSIONS: Quality-of-life impairment is similar in CIU basophil subsets. Patients with CIU with a basophil responder phenotype report longer disease duration, a higher frequency of emergency department use, and significantly higher itch severity.

Expression of activation markers on basophils in a controlled model of anaphylaxis.

BACKGROUND: Anaphylaxis has variable clinical presentations and lacks reliable biomarkers. Expression of activation markers on basophils has been useful in assessing sensitization in IgE-mediated diseases but has not been examined in vivo in anaphylaxis. OBJECTIVE: The study's goals were to assess the baseline expression of activation markers on basophils in individuals with a sting reaction history, the degree of change in expression of these markers after intentional sting challenge, and the relationship between in vitro and in vivo activation marker expression. METHODS: Patients allergic to insect venom were enrolled and grouped by clinical category defined by a history of a systemic or large local reaction and use of venom immunotherapy. Blood was collected before and after sting challenge. Enriched basophils were analyzed for activation marker expression. In select subjects, basophils were examined after in vitro stimulation with insect venom for activation marker expression and histamine release. RESULTS: Of 35 sting-challenge participants, 21 provided adequate samples for analysis. Pre-sting basophil CD63 expression was significantly higher in systemic reactors on immunotherapy. Following sting challenge, the rise in basophil CD69 expression and CD203c was significantly higher in systemic reactors on immunotherapy. Levels of activation markers on basophils were greater after in vitro venom stimulation than after in vivo challenge. CONCLUSION: Broader shifts in expression of basophil activation markers after in vivo challenge occurred among subjects with a history of in vivo systemic anaphylaxis despite venom immunotherapy. CLINICAL IMPLICATIONS: Basophil activation markers may be potential biomarkers for anaphylaxis.

Basophil FcepsilonRI histamine release parallels expression of Src-homology 2-containing inositol phosphatases in chronic idiopathic urticaria.

BACKGROUND: Basophils are implicated in the pathogenesis of chronic idiopathic urticaria (CIU). Autoantibodies to the IgE receptor (FcepsilonRI) and serum histamine releasing activity have been detected in some subjects with CIU, although their role in vivo is unclear. Basophils of patients with CIU have altered FcepsilonRI-mediated histamine release (HR); however, the mechanism is unknown. In the basophil FcepsilonRI signaling pathway, protein levels of Src-homology 2-containing-5'-inositol phosphatase (SHIP)-1 are inversely correlated with the release of mediators or releasability. A related phosphatase, SHIP-2, is a negative regulator of monocyte IgG receptor (FcgammaR) signaling . We hypothesized that SHIP levels are altered in CIU basophils. METHODS: Blood basophils were isolated from cold urticaria, CIU, or normal donors, and FcepsilonRI-dependent and independent HR were quantified. Protein levels of SHIP-1, SHIP-2, spleen tyrosine kinase, and phosphorylated Akt were determined by Western blotting. Subjects' serum was tested for serum histamine releasing activity and anti-FcepsilonRIalpha antibodies. RESULTS: CIU basophils displayed a bimodal response to anti-IgE activation. One half of CIU subjects' basophils had reductions in anti-IgE-induced HR and were designated nonresponders (CIU NR). CIU NR basophil HR remained diminished at 10-fold to 30-fold higher doses of anti-IgE. CIU anti-IgE responder basophils had HR similar to normal subjects. SHIP-1 and SHIP-2 proteins were increased in CIU NR basophils and were linked to reduced phosphoAkt after anti-IgE stimulation. CIU basophil anti-IgE response was not related to the presence of serologic factors. CONCLUSION: In CIU basophils, the observed changes in FcepsilonRI signaling pathway molecule expression may underlie changes in releasability. CLINICAL IMPLICATIONS: Patients with CIU can be segregated on the basis of basophil functional phenotype.

Successful treatment of recalcitrant chronic idiopathic urticaria with sulfasalazine.

BACKGROUND: Antihistamines are the standard treatment for chronic idiopathic urticaria (CIU). For patients whose urticaria is unresponsive to antihistamines, the treatment options are limited. During the previous decade, there have been several case reports demonstrating success with sulfasalazine therapy. In this article, we present a case series evaluating sulfasalazine therapy for antihistamine-unresponsive CIU. OBSERVATIONS: Nineteen patients with antihistamine-unresponsive CIU were treated with sulfasalazine between 2002 and 2005. During sulfasalazine therapy, 14 patients (74%) reported significant improvement, 4 patients (21%) reported minimal improvement but were not satisfied with their symptom relief, and 1 patient (5%) reported a worsening of symptoms. Of the 13 patients who required systemic steroids to control their urticaria, all were able to reduce or discontinue steroid use during sulfasalazine therapy. Although 7 patients (37%) had adverse effects (eg, nausea, headache, mild or transient leukopenia, and transaminitis) that were thought to be caused by the use of sulfasalazine, they all kept taking the drug. CONCLUSIONS: This case series demonstrates that sulfasalazine can be a successful and safe treatment option for patients with CIU who have not responded adequately to treatment with antihistamines. Sulfasalazine was steroid sparing in all subjects who were steroid dependent.

TLR9- and FcepsilonRI-mediated responses oppose one another in plasmacytoid dendritic cells by down-regulating receptor expression.

Plasmacytoid dendritic cells (pDC) express not only TLR9 molecules through which ligation with CpG DNA favors Th1 responses but also possess IgE receptors (FcepsilonRI) implicated in allergen presentation and induction of Th2 responses. This dichotomy prompted an investigation to determine whether TLR9- and IgE receptor-mediated responses oppose one another in pDC by affecting receptor expression and associated functional responses. Results showed that IgE cross-linking reduced TLR9 in pDC and inhibited the capacity of these cells to secrete IFN-alpha when stimulated with the CpG oligodeoxynucleotide (ODN)-2216. In contrast, an approximately 15-fold reduction in FcepsilonRIalpha mRNA and a loss in surface protein were seen in pDC first exposed to TLR9 ligation with ODN-2216. Results indicated that type I IFNs partly mediated this effect, as rIFN-alpha also caused a significant approximately 4-fold reduction in FcepsilonRIalpha mRNA. Finally, this reduction in FcepsilonRIalpha mediated by ODN-2216 correlated with a selective suppression of allergen-induced CD4+ T cell proliferation, but not of responses resulting from tetanus toxoid. Overall, these results imply mechanisms by which specific innate and IgE-dependent immune responses counterregulate one another at the dendritic cell level and may have significant impact on whether an ensuing response is either of Th1 or Th2 in nature.

Systemic effects of allergen exposure on blood basophil IL-13 secretion and FcepsilonRIbeta.

BACKGROUND: Airway allergen challenge studies have shown the upregulation of cytokines in local airway tissues and distal effects on bone marrow precursors for eosinophils and basophils. OBJECTIVE: We investigated whether local intranasal allergen challenge alters the phenotype of circulating basophils to a primed state. METHODS: Ten subjects with allergic rhinitis were challenged with allergen by means of intranasal spray on 3 sequential days. Basophils were isolated from subjects before challenge and 3, 24, and 96 hours after the third allergen challenge. Basophils were compared before challenge and after the last allergen challenge for levels of FcepsilonRIbeta protein by means of Western blotting and for FcepsilonRIbeta mRNA expression by means of real-time PCR. Basophils were also compared with regard to spontaneous secretion of IL-4 and IL-13. RESULTS: Basophil FcepsilonRIbeta protein levels increased in 5 of 6 subjects after allergen challenge relative to before challenge. Likewise, basophil FcepsilonRIbeta mRNA levels increased a median of 2-fold after the last challenge relative to before challenge ( P=.007, n=9). IL-13 protein was detected in supernatants of 7 of 9 subjects' basophil-enriched cultures after the last challenge compared with 3 of 9 basophil-enriched cultures before challenge (median, 6.2 vs 0 pg/mL; P=.058). IL-4 was not detected in any culture supernatant. CONCLUSION: Intranasal allergen challenge transiently activates circulating basophils by increasing expression of the FcepsilonRIbeta subunit and spontaneous IL-13 secretion. Because FcepsilonRIbeta is an amplifier of FcepsilonRI-mediated responses and IL-13 is proinflammatory, these findings support a primed basophil functional state and demonstrate a systemic effect of local allergen challenge that could contribute in exacerbating allergic reactions.